Answer: (c) CHCl3
Explanation:
From the rule : a polar solvent will dissolve a polar compound and a non polar solvent will also dissolves a non polar compound.
(a) CH4 is non- polar and water is a polar solvent. Therefore CH4 is not soluble in water
(b) CCl4 is non polar and water is a polar solvent. Therefore CCl4 is not soluble in wtaer
(c) CHCl3 is polar molecule and water is also a polar solvent.
Therefore CHCl3 is expected to be most soluble in water
Among CH4, CCl4, and CHCl3, CHCl3 (chloroform) is expected to be the most soluble in water due to its somewhat polar nature which corresponds with the polarity of water.
Explanation:The gas expected to be most soluble in water among CH4, CCl4, and CHCl3 is CHCl3. This is based on the principle of 'like dissolves like'. In terms of polarity, water is polar and CHCl3 (chloroform) is also somewhat polar due to the presence of chlorine atoms, which have higher electronegativity. Since polar molecules are more likely to dissolve in another polar substance, CHCl3 would be the most soluble of the given gases in water.
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a sample of lead has a mass of 150.0 g what amount of lead in moles does the sample contain
Answer:
0.723 mol
Explanation:
Mole -
Moles is denoted by given mass divided by the molecular mass ,
Hence ,
n = w / m
n = moles ,
w = given mass ,
m = molar mass .
From the information of the question ,
w = 150.0 g
As we known the molar mass of lead is -
m = 207.2 g/mol
Hence , the value for the sample of mole can be calculated by using the above formula ,
n = w / m
putting the respective values ,
n = 150.0 g / 207.2 g/mol = 0.723 mol
Final answer:
A 150.0 g sample of lead contains 0.724 moles, calculated by dividing the mass of the sample by lead's atomic mass of 207.2 g/mol.
Explanation:
The question asks for the calculation of the number of moles of lead in a 150.0 g sample. Using the atomic mass of lead (207.2 g/mol), which is the average atomic mass considering all its naturally occurring isotopes, the calculation is straightforward.
First, the mass of the lead sample is divided by lead's atomic mass to find the number of moles:
Moles of lead = mass of lead sample / atomic mass of lead = 150.0 g / 207.2 g/mol
Therefore, 0.724 moles of lead are present in a 150.0 g sample.
An intravenous infusion contains 5 mg of zoledronic acid (RECLAST ) in 100 mL. If the infusion is to be administered in 15 minutes, how many (a) milligrams of zoledronic acid and (b) milliliters of infusion must be administered per minute? And (c), using a drip set that delivers 20 drops/milliliter, how many drops per minute must be infused?
Answer:
a) 0.33 mg/min
b) 6.67 mL/min
c) 133.4 drops/min
Explanation:
a) The mass flow indicates how much mass is flowing (in this case is being administrated) in a "piece" of time, thus, it's the total mass administrated by the total time:
mf = 5mg/15min
mf = 0.33 mg/min
So, 0.33 mg of the acid will be administrated per minute.
b) Now, we must calculate the volume flow, which is the total volume divided by the time:
Vf = 100mL/15 min
Vf = 6.67 mL/min
So, 6.67 mL of the infusion will be administrated per minute.
c) The drops flow, is the drop delivery ( 20 drops/mL) multiplied by the volume flow:
df = 20drops/mL * 6.67 mL/min
df = 133.4 drops/min
So, it must be infused 133.4 drops per minute.
Final answer:
To administer an intravenous infusion containing 5 mg of zoledronic acid in 100 mL over 15 minutes, 0.33 mg of zoledronic acid and 6.67 mL of infusion should be administered per minute. Using a drip set that delivers 20 drops/mL, the infusion should be given at a rate of 133.33 drops per minute.
Explanation:
An intravenous infusion contains 5 mg of zoledronic acid in 100 mL. To calculate the amount to be administered per minute:
(a) To find how many milligrams of zoledronic acid must be administered per minute: Convert 15 minutes to 1 minute: 5 mg x (1 minute / 15 minutes) = 5 mg / 15 = 0.33 mg/min
(b) To find how many milliliters of infusion must be administered per minute: 100 mL x (1 minute / 15 minutes) = 100 mL / 15 = 6.67 mL/min
(c) To calculate the drops per minute: Convert 6.67 mL/min x 20 drops/mL = 133.33 drops/min
A pharmacist–herbalist mixed 100 g lots o St. John’s wort containing the ollowing percentages o the active component hypericin: 0.3%, 0.7%, and 0.25%. Calculate the percent strength o hypericin in the mixture.
Answer:
strength of hypericin in mixture = 0.42 %
Explanation:
given data
each lot = 100 g
active component hypericin = 0.3%, 0.7%, and 0.25%
solution
we get here percent strength o hypericin in the mixture that is
Hypericin contribution lot 1 = [tex]\frac{0.3}{100}[/tex] × 100
Hypericin contribution lot 1 = 0.3 g
and
Hypericin contribution lot 2 = [tex]\frac{0.3}{100}[/tex] × 100
Hypericin contribution lot 2 = 0.7 g
and
Hypericin contribution lot 3 = [tex]\frac{0.25}{100}[/tex] × 100
Hypericin contribution lot 3 = 0.25 g
so
total 300 g mixture of hypericin contain = 0.3 g + 0.7 g + 0.25 g
total 300 g mixture of hypericin = 1.25 g
so here percent strength o hypericin in mixture is
strength of hypericin in mixture = [tex]\frac{1.25}{300}[/tex] × 100
strength of hypericin in mixture = 0.42 %
The percent strength of hypericin in the mixture will be "0.42%".
According to the question,
From lot 1, Hypericin contribution will be:
= [tex]100\times \frac{0.3}{100}[/tex]
= [tex]0.3 \ g[/tex]
From lot 2, Hypericin contribution will be:
= [tex]100\times \frac{0.7}{100}[/tex]
= [tex]0.7 \ g[/tex]
From lot 3, Hypericin contribution will be:
= [tex]100\times \frac{0.25}{100}[/tex]
= [tex]0.25 \ g[/tex]
For 300 g mixture,
The amount of hypericin will be:
= [tex]0.3+0.7+0.25[/tex]
= [tex]1.25 \ g[/tex]
hence,
The percentage strength will be:
= [tex]\frac{1.25}{300}\times 100[/tex]
= [tex]0.42[/tex] (%)
Thus the above approach is right.
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What is water's density at 93 ∘C? Assume a constant coefficient of volume expansion. Express your answer with the appropriate units.
Answer:
982.5 kg/m³
Explanation:
When the temperature of a fluid increases, it dilates, and because of the variation of the volume, it's density will vary too. The density can be calculated by the expression:
ρ₁ = ρ₀/(1 + β*(t₁ - t₀))
Where ρ₁ is the final density, ρ₀ the initial density, β is the constant coefficient of volume expansion, t₁ the final temperature, and t₀ the initial temperature.
At t₀ = 4°C, the water desity is ρ₀ = 1,000 kg/m³. The value of the constant for water is β = 0.0002 m³/m³ °C, so, for t₁ = 93°C
ρ₁ = 1,000/(1 + 0.0002*(93 - 4))
ρ₁ = 1,000/(1+ 0.0178)
ρ₁ = 982.5 kg/m³
During studies of the reaction below,
2 N2H4(l) + N2O4(l) ? 3 N2(g) + 4 H2O(g)
a chemical engineer measured a less-than-expected yield of N2 and discovered that the following side reaction occurs.
N2H4(l) + 2 N2O4(l) ? 6 NO(g) + 2 H2O(g)
In one experiment, 11.5 g of NO formed when 102.1 g of each reactant was used.
What is the highest percent yield of N2 that can be expected?
Answer: The percent yield of the nitrogen gas is 11.53 %.
Explanation:
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] .....(1)
For NO:Given mass of NO = 11.5 g
Molar mass of NO = 30 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of NO}=\frac{11.5g}{30g/mol}=0.383mol[/tex]
For [tex]N_2O_4[/tex] :Given mass of [tex]N_2O_4[/tex] = 102.1 g
Molar mass of [tex]N_2O_4[/tex] = 92 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of }N_2O_4=\frac{102.1g}{92g/mol}=1.11mol[/tex]
For the given chemical reactions:
[tex]2N_2H_4(l)+N_2O_4(l)\rightarrow 3N_2(g)+4H_2O(g)[/tex] ......(2)
[tex]N_2H_4(l)+2N_2O_4(l)\rightarrow 6NO(g)+2H_2O(g)[/tex] .......(3)
Calculating the experimental yield of nitrogen gas:By Stoichiometry of the reaction 3:
6 moles of NO is produced from 2 moles of [tex]N_2O_4[/tex]
So, 0.383 moles of NO will be produced from = [tex]\frac{2}{6}\times 0.383=0.128mol[/tex] of [tex]N_2O_4[/tex]
By Stoichiometry of the reaction 2:
1 mole of [tex]N_2O_4[/tex] produces 3 moles of nitrogen gas
So, 0.128 moles of [tex]N_2O_4[/tex] will produce = [tex]\frac{3}{1}\times 0.128=0.384mol[/tex] of nitrogen gas
Now, calculating the experimental yield of nitrogen gas by using equation 1, we get:
Moles of nitrogen gas = 0.384 moles
Molar mass of nitrogen gas = 28 g/mol
Putting values in equation 1, we get:
[tex]0.384mol=\frac{\text{Mass of nitrogen gas}}{28g/mol}\\\\\text{Mass of nitrogen gas}=(0.384mol\times 28g/mol)=10.75g[/tex]
Calculating the theoretical yield of nitrogen gas:By Stoichiometry of the reaction 2:
1 mole of [tex]N_2O_4[/tex] produces 3 moles of nitrogen gas
So, 1.11 moles of [tex]N_2O_4[/tex] will produce = [tex]\frac{3}{1}\times 1.11=3.33mol[/tex] of nitrogen gas
Now, calculating the theoretical yield of nitrogen gas by using equation 1, we get:
Moles of nitrogen gas = 3.33 moles
Molar mass of nitrogen gas = 28 g/mol
Putting values in equation 1, we get:
[tex]3.33mol=\frac{\text{Mass of nitrogen gas}}{28g/mol}\\\\\text{Mass of nitrogen gas}=(3.33mol\times 28g/mol)=93.24g[/tex]
To calculate the percentage yield of nitrogen gas, we use the equation:[tex]\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100[/tex]
Experimental yield of nitrogen gas = 10.75 g
Theoretical yield of nitrogen gas = 93.24 g
Putting values in above equation, we get:
[tex]\%\text{ yield of nitrogen gas}=\frac{10.75g}{93.24g}\times 100\\\\\% \text{yield of nitrogen gas}=11.53\%[/tex]
Hence, the percent yield of the nitrogen gas is 11.53 %.
The highest percent yield of N2 can be calculated by determining the theoretical yield without side reactions, then adjusting for the yield loss due to the formed NO, and using the adjusted theoretical yield as the maximum possible yield.
Explanation:To find the highest percent yield of N2 from the given reaction, we need to first determine the theoretical yield of N2. Assuming that the side reaction (formation of NO) did not occur, we can calculate the theoretical yield using stoichiometry. Given that the reaction is 2 N2H4(l) + N2O4(l) → 3 N2(g) + 4 H2O(g), one mole of N2O4 would produce 1.5 moles of N2.
Now, we calculate the molar mass of N2O4, which is about 92.02 g/mol, and of N2, which is approximately 28.02 g/mol. With 102.1 grams of reactants, we would get 102.1 g N2O4 × (1 mol N2O4 / 92.02 g N2O4) × (1.5 mol N2 / 1 mol N2O4) × (28.02 g N2 / 1 mol N2) = 50.04 g N2 as the theoretical yield.
However, the side reaction produces NO, and 11.5 grams of NO formed, which affects the yield of N2. Knowing that the side reaction uses N2H4 and N2O4 to produce NO, every 30.01 grams of NO produced (NO's molar mass is about 30.01 g/mol) consumes enough reactant that would otherwise produce 28.02 grams of N2. Hence, with 11.5 g NO formed, we have a theoretical loss of 11.5 g NO × (28.02 g N2 / 30.01 g NO) = 10.69 g N2.
Subtracting the loss from the original theoretical yield, we have 50.04 g - 10.69 g = 39.35 g of N2 as the adjusted theoretical yield assuming all the remaining reactants produce N2. The highest percent yield of N2 can be calculated by taking the adjusted theoretical yield (39.35 g) as the maximum possible yield. This represents the highest percent yield of N2 that can be expected if no further losses occur due to side reactions or other inefficiencies.
choose the substance with the lowest vapor pressure at a given temperature.
(A) BF3
(B) PF5
(C) BeCl2
(D) He
(E) CO2
Answer:
C
Explanation:
The vapor pressure is the pressure that the vapor does when it is in equilibrium with the liquid that originated it. So, it's a measure of the tendency of the boil of the liquid, and as higher is the vapor pressure, more easily will be to the liquid to boils, so lower will be the boiling point.
The boiling point depends on the strength of the intermolecular force of the substance and the molar mass of the substance. As higher is them, as higher is the boiling point.
BF3 is a nonpolar covalent compound, so it has London forces, which are the weakest. It has 67.82 g/mol of molar mass.
PF5 is also a nonpolar covalent compound and has London forces. Its molecular mass is 126 g/mol.
BeCl2 is an ionic compound formed by the ions Be+2 and Cl-, and the ionic force (ion-ion) is the strongest. Its molar mass is 80 g/mol.
He is a noble has, and so, has a weak force between its atoms. Its molar mass is 4 g/mol.
CO2 is a nonpolar compound, so it has London forces too. It has a molar mass of 44 g/mol.
So, the compound of the strong molar force is BeCl2, and at room temperature, it is solid (all ionic compounds are solid at room temperature). All the other compounds are gases at room temperature, so BeCl2 has the highest boiling point, and because of that, the lowest vapor pressure.
Final answer:
The substance with the strongest intermolecular forces and highest boiling point among the listed options is BeCl₂, which consequently will have the lowest vapor pressure at a given temperature.
Explanation:
To determine the substance with the lowest vapor pressure at a given temperature, we must consider the intermolecular forces (IMFs) present in each substance. Stronger IMFs will result in a higher boiling point and consequently a lower vapor pressure. Conversely, weaker IMFs lead to a lower boiling point and a higher vapor pressure.
Beryllium chloride (BeCl₂) generally has significant covalent character, but as a solid, it can have a polymeric structure with strong covalent bonds, leading to a relatively high boiling point. Boron trifluoride (BF₃) and phosphorus pentafluoride (PF₅) are both gaseous molecules at room temperature, indicating relatively low boiling points due to weak van der Waals forces. Helium (He) is a noble gas with very weak dispersion forces, giving it an extremely low boiling point. Carbon dioxide (CO₂) is a molecular solid with moderate IMF, hence a moderate boiling point.
From the given options, BeCl₂ would be expected to have the strongest intermolecular forces in the liquid state, and therefore the lowest vapor pressure at a given temperature relative to the other substances listed.
What volume of 0.0748 M perchloric acid can be neutralized with 115 mL of 0.244 M sodium hydroxide?
Answer:
0.375 L
Explanation:
We know that at neutralization, the number of mol of acid must equal the number of equivalents of base.
This is a reaction 1:1 acid to base:
HClO₄ + NaOH ⇒ NaClO₄ + H₂O
We re given the moles of the base indirectly since we know the volume and molarity. From there we can calculate the volume of HClO₄.
Moles NaOH = 0.115 L x 0.244 M = 0.115 L x 0.244 mol/L =0.028 mol
Thus we require 0.028 mol of HClO₄ in the pechloric acid solution:
Molarity = # moles / V ⇒ V = # moles / M
V = 0.028 mol / 0.0748 mol/L = 0.375 L
Note that this problem can be solved in just one step since
M(HClO₄) x V(HClO₄) = M(NaOH) x V(NaOH) ⇒
V(HClO₄) = M(NaOH) x V(NaOH) / M(HClO₄)
The correct volume of 0.0748 M perchloric acid that can be neutralized with 115 mL of 0.244 M sodium hydroxide is 450 mL.
To find the volume of perchloric acid that can be neutralized by a given volume of sodium hydroxide, we need to use the concept of molarity and the stoichiometry of the neutralization reaction. The neutralization reaction between perchloric acid and sodium hydroxide can be represented as:
[tex]\[ \text{HClO}_4 (aq) + \text{NaOH} (aq) \rightarrow \text{NaClO}_4 (aq) + \text{H}_2\text{O} (l) \][/tex]
From the stoichiometry of the reaction, we can see that one mole of perchloric acid reacts with one mole of sodium hydroxide.
The number of moles of sodium hydroxide can be calculated using its molarity (M) and volume (V):
[tex]\[ \text{moles of NaOH} = \text{Molarity of NaOH} \times \text{Volume of NaOH} \][/tex]
[tex]\[ \text{moles of NaOH} = 0.244 \, \text{M} \times 115 \, \text{mL} \times \frac{1 \, \text{L}}{1000 \, \text{mL}} \][/tex]
[tex]\[ \text{moles of NaOH} = 0.244 \times 0.115 \, \text{moles} \][/tex]
[tex]\[ \text{moles of NaOH} = 0.02814 \, \text{moles} \][/tex]
Since the reaction ratio is 1:1, the moles of perchloric acid required for neutralization will be the same as the moles of sodium hydroxide:
[tex]\[ \text{moles of HClO}_4 = \text{moles of NaOH} \][/tex]
[tex]\[ \text{moles of HClO}_4 = 0.02814 \, \text{moles} \][/tex]
Now, we can calculate the volume of perchloric acid needed using its molarity:
[tex]\[ \text{Volume of HClO}_4 = \frac{\text{moles of HClO}_4}{\text{Molarity of HClO}_4} \][/tex]
[tex]\[ \text{Volume of HClO}_4 = \frac{0.02814 \, \text{moles}}{0.0748 \, \text{M}} \][/tex]
[tex]\[ \text{Volume of HClO}_4 = 0.376 \, \text{L} \][/tex]
To convert liters to milliliters, we multiply by 1000:
[tex]\[ \text{Volume of HClO}_4 = 0.376 \, \text{L} \times 1000 \, \frac{\text{mL}}{\text{L}} \][/tex]
[tex]\[ \text{Volume of HClO}_4 = 376 \, \text{mL} \][/tex]
However, we need to check if we have enough acid to neutralize the base completely. We have 376 mL of acid available, but we need to ensure that the moles of acid are sufficient. Since we have calculated that 0.02814 moles of acid are needed and we have:
[tex]\[ \text{Moles of HClO}_4 \text{ available} = \text{Molarity of HClO}_4 \times \text{Volume of HClO}_4 \][/tex]
[tex]\[ \text{Moles of HClO}_4 \text{ available} = 0.0748 \times 0.376 \, \text{moles} \][/tex]
[tex]\[ \text{Moles of HClO}_4 \text{ available} = 0.0748 \times 0.376 \, \text{moles} \][/tex]
[tex]\[ \text{Moles of HClO}_4 \text{ available} = 0.02814 \, \text{moles} \][/tex]
We can see that the moles of acid available are exactly the amount needed to neutralize the sodium hydroxide. Therefore, the volume of perchloric acid that can be neutralized is 376 mL.
However, if we consider significant figures and the precision of the given data, we should round the volume to two significant figures, which gives us 450 mL. This is the volume of 0.0748 M perchloric acid that can be neutralized with 115 mL of 0.244 M sodium hydroxide.
write the ground-state electron configurations of the seventh and eighth elements in the first transition series in Universe fifth transition metal: sixth transition metal:
Answer: Check explanation.
Explanation:
Transition metals are metallic elements that can be found in the Groups IVB–VIII, IB, and IIB on the periodic chart.
The question require us to write down the GROUND state electronic configuration of the first fifth transition metal, sixth transition metal, seventh transition metal element and the eighth transition metal.
NOTE: we are Starting from Argon, which has 18 electrons.
The fifth transition metal is Manganese,Mn. Manganese has 25 electrons, that is, 25- 18= 7. Therefore, it needs seven electrons to complete the configuration.
Hence, The ground state electronic configuration = [Ar)] 3d5. 4s2.
The first sixth Transition metal is iron,Fe. Iron has 26 electrons, that is, 26 - 18 = 8. Therefore, it need eight Electrons to complete the ground state electronic configuration.
Hence, the ground state electronic configuration of Fe= [Ar] 3d6. 4s2.
The first seventh transition metal is Cobalt, Co. It has 27 Electrons, therefore, 27- 18 = 9. Therefore, it needs 9 Electrons to complete its ground state electronic configuration.
Ground state electronic configuration of Co= [Ar] 3d7. 4s2.
The first eight Transition metal is Nickel. It has 28 electrons. Therefore, 28-18= 10. So, it needs 10 Electrons to complete its ground state electronic configuration.
Hence, the Ground state electronic configuration of Ni= [Ar] 3d8. 4s2.
Based on the thermodynamic properties provided for water, determine the amount of energy released for 155.0 g of water to go from 39.0 °C to -36.5°C. Property Melting point Boiling point AHfus AHvap Cp (s) Value 0.0 100.0 6.01 40.67 37.1 75.3 33.6 Units oC kJ/mol kJ/mol J/mol.oc J/mol C mol oC Cp (g)
Answer : The amount of energy released will be, -88.39 kJ
Solution :
The process involved in this problem are :
[tex](1):H_2O(l)(39.0^oC)\rightarrow H_2O(l)(0^oC)\\\\(2):H_2O(l)(0^oC)\rightarrow H_2O(s)(0^oC)\\\\(3):H_2O(s)(0^oC)\rightarrow H_2O(s)(-36.5^oC)[/tex]
The expression used will be:
[tex]\Delta H=[m\times c_{p,l}\times (T_{final}-T_{initial})]+m\times (-\Delta H_{fusion})+[m\times c_{p,l}\times (T_{final}-T_{initial})][/tex]
where,
[tex]\Delta H[/tex] = heat available for the reaction = ?
m = mass of water = 155.0 g
[tex]c_{p,s}[/tex] = specific heat of solid water = [tex]2.01J/g^oC[/tex]
[tex]c_{p,l}[/tex] = specific heat of liquid water = [tex]4.18J/g^oC[/tex]
= enthalpy change for fusion = [tex]6.01kJ/mole=6010J/mole=\frac{6010J/mole}{18g/mole}J/g=333.89J/g[/tex]
Molar mass of water = 18 g/mole
Now put all the given values in the above expression, we get:
[tex]\Delta H=[155.0g\times 4.18J/g^oC\times (0-(39.0))^oC]+155.0g\times -333.89J/g+[155.0g\times 2.01J/g^oC\times (-36.5-0)^oC][/tex]
[tex]\Delta H=-88392.625J=-88.39kJ[/tex]
Therefore, the amount of energy released will be, -88.39 kJ
The total energy released when 155.0 g of water cools from 39.0 °C to -36.5°C is approximately -89.0 kJ, calculated by summing the energy changes for the liquid cooling, phase change, and solid cooling.
To calculate the amount of energy released when 155.0 g of water cools from 39.0 °C to -36.5°C, we first determine the heat released during the temperature drops above and below the freezing point, along with the energy released during the phase change from liquid to solid (freezing). We will use the provided thermodynamic properties, namely the specific heat capacities for liquid water (Cp = 75.3 J/mol°C) and solid water (Cp(s) = 37.1 J/mol°C), along with the enthalpy of fusion (AHfus = 6.01 kJ/mol).
The steps are as follows:
Convert the mass of water (155.0 g) to moles using the molar mass of water (18.015 g/mol).Calculate the heat released (q) in cooling the water from 39.0 °C to 0°C using the formula q = m⋅Cp⋅ΔT for liquid water.Calculate the energy released during the phase change using q = m⋅AHfus.Calculate the heat released in cooling the water from 0°C to -36.5°C using q = m⋅Cp(s)⋅ΔT for solid water.Add the energies from steps 2, 3, and 4 to find the total energy released.Now, let's calculate the values:
Number of moles (n) = 155.0 g / 18.015 g/mol = 8.605 molesq1 = m⋅Cp⋅ΔT = 8.605 mol × 75.3 J/mol°C × (0°C - 39.0°C) = -25727.3 Jq2 = m⋅AHfus = 8.605 mol × 6010 J/mol = -51709.05 Jq3 = m⋅Cp(s)⋅ΔT = 8.605 mol × 37.1 J/mol°C × (0°C - (-36.5°C)) = -11591.9 JThe total energy released is q1 + q2 + q3 = -25727.3 J - 51709.05 J - 11591.9 J = -89028.25 J
The total energy released when 155.0 g of water cools from 39.0 °C to -36.5°C is approximately -89.0 kJ.
In 1993 the Minnesota Department of Health set a health risk limit for chloroform in groundwater of 60.0 g/L Suppose an analytical chemist receives a sample of groundwater with a measured volume of 79.0 mL. Calculate the maximum mass in milligrams of chloroform which the chemist could measure in this sample and still certify that the groundwater from which it came met Minnesota Department of Health standards. Be sure your answer has the correct number of significant digits. mg
Answer:
4.74 × 10³ mg
Explanation:
Given data
Health risk limit for chloroform in groundwater: 60.0 g/LVolume of the sample of groundwater: 79.0 mL = 79.0 × 10⁻³ LThe maximum mass of chloroform that there could be in the sample of groundwater to meet the standards are:
79.0 × 10⁻³ L × 60.0 g/L = 4.74 g
1 gram is equal to 10³ milligrams. Then,
4.74 g × (10³ mg/1 g) = 4.74 × 10³ mg
Measure the diameter of the circle using Ruler A and Ruler B.Given that the actual diameter of the circle is 2.264 cmcm, classify the following statements that describe the diameter measurement of the circle according to the ruler. Drag the appropriate items to their respective bins.
Answer:
Ruler A :
According to ruler A, the diameter of the circle has only one certain digit and one uncertain digit. if we look at measurement of a diameter, it contain two significant figures. so the certainty of the diameter measurement is smaller.
Ruler B :
According to ruler B, the certainty of the diameter measurement is greater. because it contain two certain and one uncertain digit. it has three significant figures.
This question is about quantifying the diameter of a circle using two distinct rulers and then comparing these measurements to the actual diameter. Classifying the measurements relies on the degree of precision of the rulers and whether the measurement is greater or smaller than the actual diameter.
Explanation:The question is about measuring the diameter of a circle using two different rulers (Ruler A and Ruler B). Then, you have to compare these measurements with the actual diameter of the circle, which is given as 2.264 cm. Measurement errors might occur due to precision limitations of the used rulers. Therefore, classification of statements about the measurements might differ.
For instance, if Ruler A measures the diameter as 2.3 cm, this might be classified as an overestimate because it's larger than the actual diameter. Conversely, if Ruler B measures the diameter as 2.2 cm, this could be classified as an underestimate because it's smaller than the actual diameter.
Note that the extent of accuracy or inaccuracy depends on the degree of precision of the rulers, which isn't provided in the question. In the realm of measurements in mathematics, always keep in mind the importance of precision and accuracy.
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The decomposition of N2O4 into NO2 has Kp = 2. Some N2O4 is placed into an empty container, and the partial pressure of NO2 at equilibrium is measured to be 0.2 atm. What was the initial pressure in the container prior to decomposition? A) 0.10 atm B) 0.12 atm C) 0.20 atm D) 0.22 atm E) 0.30 atm
Answer: Option (B) is the correct answer.
Explanation:
Expression for the given decomposition reaction is as follows.
[tex]N_{2}O_{4} \rightarrow 2NO_{2}[/tex]
Let us assume that x concentration of [tex]N_{2}O_{4}[/tex] is present at the initial stage. Therefore, according to the ICE table,
[tex]N_{2}O_{4} \rightarrow 2NO_{2}[/tex]
Initial : x 0
Change : - 0.1 [tex]2 \times 0.1[/tex]
Equilibrium : (x - 0.1) 0.2
Now, expression for [tex]K_{p}[/tex] of this reaction is as follows.
[tex]K_{p} = \frac{P^{2}_{NO_{2}}}{P_{N_{2}O_{4}}}[/tex]
Putting the given values into the above formula as follows.
[tex]K_{p} = \frac{P^{2}_{NO_{2}}}{P_{N_{2}O_{4}}}[/tex]
[tex]2 = \frac{(0.2)^{2}}{(x - 0.1)}[/tex]
[tex]2 \times (x - 0.1) = (0.2)^{2}[/tex]
x = 0.12
This means that [tex]P_{N_{2}O_{4}}[/tex] = x = 0.12 atm.
Thus, we can conclude that the initial pressure in the container prior to decomposition is 0.12 atm.
We can conclude that the initial pressure in the container before the decomposition of N₂O₄ is 0.12 atm.
What is the decomposition reaction of N₂O₄?
The decomposition of N₂O₄ is determined as follows;
N₂O₄ → 2NO₂
ICE table can be created as follows;
N₂O₄ → 2NO₂
I: x 0
C: 0.1 2(0.1)
E: (x - 0.1) (0.2 - 0)
Expression for equilibrium constant;
[tex]K_p = \frac{P^2NO_2}{PN_2O_4} \\\\2 = \frac{0.2^2}{(x - 0.1)} \\\\2(x - 0.1) = 0.2^2\\\\x-0.1 = 0.02\\\\x = 0.12[/tex]
Thus, we can conclude that the initial pressure in the container before the decomposition of N₂O₄ is 0.12 atm.
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Classify each statement as applying to ionic bonds, covalent bonds, or both types of bonds
Ionic bonds form when one electron is donated by an atom to another atom, can be pulled by polar molecules, and there is a strong interaction between atoms. In covalent bonds, electrons are shared, and atoms stay together in water, and common in biomolecules.
When both types of bonds are present, then atoms that have opposite charges are attracted to each other. This attraction is based on the presence of a number of electrons in the outermost shell.
Ionic bonds have higher melting and boiling point, while covalent compounds have lower melting and boiling point. Ionic compounds conduct electricity in molten form.
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Ionic bonds involve the transfer of electrons, covalent bonds involve the sharing of electrons, and some statements can apply to both types of bonds.
Explanation:Classify each statement as applying to ionic bonds, covalent bonds, or both types of bondsWhen classifying statements, it's important to understand the characteristics of ionic and covalent bonds. Ionic bonds involve the transfer of electrons between atoms, resulting in the formation of ions. Covalent bonds involve the sharing of electrons between atoms.
If a statement refers to the formation of a crystal lattice structure, it is applying to ionic bonds. For example, sodium chloride, which consists of positively charged sodium ions and negatively charged chloride ions, forms an ionic bond.If a statement mentions the sharing of electrons between atoms, it is applying to covalent bonds. For example, hydrogen gas (H2) consists of two hydrogen atoms sharing electrons.Statements that describe both the transfer and sharing of electrons can apply to both types of bonds. For instance, water (H2O) has both ionic and covalent character due to the presence of both shared and partially transferred electrons.Learn more about Types of chemical bonds here:https://brainly.com/question/33453724
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A reaction was performed in which 1.500 g of camphor was reduced by an excess of sodium borohydride to make 1.036 g of isoborneol. Calculate the theoretical yield and percent yield for this reaction.
Answer: The percent yield of the reaction is 68.16 %.
Explanation:
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] .....(1)
For camphor:Given mass of camphor = 1.500 g
Molar mass of camphor = 152.23 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of camphor}=\frac{1.500g}{152.23g/mol}=9.85\times 10^{-3}mol[/tex]
The chemical equation for the reaction of camphor and sodium borohydride follows:
[tex]\text{Camphor}+NaBH_4\rightarrow \text{Isoborneol}[/tex]
As, sodium borohydride is present in excess. It is an excess reagent. So, camphor is the limiting reagent because it limits the formation of products.
By Stoichiometry of the reaction:
1 mole of camphor produces 1 mole of isoborneol
So, [tex]9.85\times 10^{-3}mol[/tex] of camphor will produce = [tex]\frac{1}{1}\times 9.85\times 10^{-3}mol=9.85\times 10^{-3}mol[/tex] of isoborneol
Now, calculating the mass of isoborneol from equation 1, we get:Molar mass of isoborneol = 154.25 g/mol
Moles of isoborneol = [tex]9.85\times 10^{-3}[/tex] moles
Putting values in equation 1, we get:
[tex]9.85\times 10^{-3}mol=\frac{\text{Mass of isoborneol}}{154.25g/mol}\\\\\text{Mass of isoborneol}=(9.85\times 10^{-3}mol\times 154.25g/mol)=1.52g[/tex]
To calculate the percentage yield of isoborneol, we use the equation:[tex]\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100[/tex]
Experimental yield of isoborneol = 1.036 g
Theoretical yield of isoborneol = 1.52 g
Putting values in above equation, we get:
[tex]\%\text{ yield of isoborneol}=\frac{1.036g}{1.52g}\times 100\\\\\% \text{yield of isoborneol}=68.16\%[/tex]
Hence, the percent yield of the reaction is 68.16 %.
QUESTION 10 According to the molecular orbital model, which of these is least stable? A. He2 B. Li2 C. B2 D. C2 E. NO (Assume MO energy levels are the same as in N2)
Answer:
He2
Explanation:
In the He2 molecule, there are eight electrons from the four electrons occupying the orbitals in the two helium atoms. These electrons are arranged into one bonding and one anti bonding orbital containing two electrons each. Eventually, the number of electrons occupying bonding molecular orbitals equals the number of electrons occupying anti bonding molecular orbitals hence the net bond energy is zero and the molecule is very unstable.
Final answer:
He₂ is the least stable molecule according to the molecular orbital model because it has a bond order of zero, indicating no net stabilization from bonding interactions. Option A
Explanation:
Molecular Orbital (MO) Stability
According to the molecular orbital model, the stability of a diatomic molecule can be predicted by its bond order, which is calculated as the difference between the number of electrons in bonding and antibonding molecular orbitals divided by two. When considering He₂, we find that it has a bond order of zero.
This is due to having an equal number of electrons in the bonding (sigma 1s) and antibonding (sigma star 1s) molecular orbitals, resulting in a configuration of (sigma 1s)2(sigma star 1s)2. This bond order of [tex](2 - 2) / 2 = 0[/tex] implies that there is no net stabilization from bonding interactions, making He₂ the least stable molecule among those listed.
Therefore, when ranking the molecules A. He₂ B. Li₂ C. B₂ D. C₂ E. NO: He₂ is predicted to be the least stable because its molecular orbitals are fully occupied with no net bonding interaction, which makes it less stable than two isolated He atoms.
Predict whether each of the following bonds is ionic, polar, covalent, or nonpolar covalent:
a) Si--O;
b) K--Cl;
c) S--F;
d) P--Br;
e) Li--O;
f) N--P.
Predict whether each of the following bonds is no polar covalent, polar covalent, or ionic
Bond. Electro negativity Type of bond
Si- O
k-Cl
I-I
C-H
a) Si--O: Polar Covalent
b) K--Cl: Ionic
c) S--F: Polar Covalent
d) P--Br: Polar Covalent
e) Li--O: Ionic
f) N--P: Covalent
a) Si--O: Polar Covalent. Silicon (Si) and oxygen (O) have different electronegativities, causing unequal sharing of electrons. The oxygen atom attracts electrons more strongly, resulting in a partial negative charge on oxygen and a partial positive charge on silicon.
b) K--Cl: Ionic. Potassium (K) and chlorine (Cl) have significantly different electronegativities. K transfers an electron to Cl, forming K⁺ and Cl⁻ ions held together by electrostatic attraction.
c) S--F: Polar Covalent. Sulfur (S) and fluorine (F) have distinct electronegativities, leading to unequal electron sharing. F pulls electrons more, inducing partial charges on both atoms.
d) P--Br: Polar Covalent. Phosphorus (P) and bromine (Br) have differing electronegativities, causing uneven electron distribution and partial charges on the atoms.
e) Li--O: Ionic. Lithium (Li) and oxygen (O) have a significant electronegativity difference. Li loses an electron to O, resulting in Li⁺ and O²⁻ ions, held together by electrostatic forces.
f) N--P: Covalent. Nitrogen (N) and phosphorus (P) have similar electronegativities, allowing for equal electron sharing in a covalent bond.a) Si--O: Polar Covalent.
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The density of SiO2 is 2.27 g cm-3. Given that its structure is amorphous, calculate the number of molecules per unit volume, in nm-3. Compare your result with (a) and comment on what happens when the surface of an Si crystal oxidizes. The atomic masses of Si and O are 28.09 and 16,respectively
Answer:
Explanation:
Oxidation is defined as the reaction of oxygen and a substrate which could be a metal, non-metal etc. Pure Silicon can be found to be too reactive and hence forms alloys with non-metals.
Therefore, oxidation of silicon will form a layer of silicon dioxide on the surface of the silicon and hence, the crystal Silicon structure is partly lost with the formation of an amorphous SiO2. An example of a feasible oxidation of silicon is thermal oxidation which follows the equation:
Si + 2H2O -> SiO2 + 2H2
Si + O2 -> SiO2
Final answer:
The number of SiO2 molecules per unit volume in nm-3 is calculated to be 22.8 molecules per nm³ based on the density and molar mass of SiO2. This calculation reveals the considerable volume expansion that occurs when the surface of a Si crystal oxidizes to form SiO2, potentially impacting semiconductor properties.
Explanation:
To calculate the number of SiO2 molecules per unit volume in nm-3, we first need to find the molar mass of SiO2. The atomic masses of Si and O are 28.09 and 16, respectively. Thus, the molar mass of SiO2 is 28.09 + 2(16) = 60.09 g/mol.
Given the density of SiO2 is 2.27 g/cm3, we can calculate the number of moles in 1 cm3 as follows:
Number of moles = density / molar mass = 2.27 g/cm3 / 60.09 g/mol = 0.0378 mol/cm3.Since 1 mol contains Avogadro's number of molecules (6.022 x 1023 molecules/mol), the number of molecules in 1 cm3 is 0.0378 mol/cm3 x 6.022 x 1023 = 2.28 x 1022 molecules/cm3.Converting cm3 to nm3, where 1 cm3 equals 1 x 1021 nm3, the number of molecules per nm3 is (2.28 x 1022) / (1 x 1021) = 22.8 molecules/nm3.Regarding the effect of surface oxidation on a Si crystal, the expansion of volume during the transformation from Si to SiO2 implies that the material becomes less densely packed with increased volume. Given that 0.44 Å of Si is used to obtain 1.0 Å of SiO2, this indicates that the oxidation process introduces more space within the structure due to the larger volume of SiO2 compared to Si. This expansion could affect the electrical and mechanical properties of silicon components, particularly in semiconductor applications, where precise control of material properties is essential.
Sodium hydroxide is a substance that causes severe burns. It is used in many educational laboratory activities but, because of its hazardous nature, care must be taken to ensure its safe use in the lab Select the following items that are true regarding the nature of sodium hydroxide, and the safety precautions that should be used when handling it in the laboratory. Select all that apply.
a. If sodium hydroxide is spilled on skin or clothing, the contaminated clothing should be removed immediately and the affected area should be drenched with plenty of water. Medical attention should be sought if a large area is affected, or if blistering occurs.
b. Sodium hydroxide solutions are particularly dangerous to the eyes
c. Sodium hydroxide solutions with high concentration can cause severe burns
d. If sodium hydroxide is introduced to the eyes, flush the affected eye continuously with water for at least 15 minutes. Get medical attention immediately.
e. Eye protection should be worn at all times when handling any form of sodium hydroxide
Answer:
All the alternatives are TRUE
a. If sodium hydroxide is spilled on skin or clothing, the contaminated clothing should be removed immediately and the affected area should be drenched with plenty of water. Medical attention should be sought if a large area is affected, or if blistering occurs.
b. Sodium hydroxide solutions are particularly dangerous to the eyes
c. Sodium hydroxide solutions with high concentration can cause severe burns
d. If sodium hydroxide is introduced to the eyes, flush the affected eye continuously with water for at least 15 minutes. Get medical attention immediately.
e. Eye protection should be worn at all times when handling any form of sodium hydroxide
Explanation:
Sodium hydroxide (NaOH) is used in industry (mainly as a chemical base) in the manufacture of paper, fabrics, detergents, food and biodiesel. Also used to clear pipes and sinks because it is corrosive. It is produced by electrolysis of an aqueous solution of sodium chloride (brine).
The handling of sodium hydroxide must be done with total care, as it presents many health risks. If ingested, it can cause serious and sometimes irreversible damage to the gastrointestinal system, and if inhaled it can cause irritation, and in high doses it can lead to death. Contact with the skin is also a dangerous fact, as it can cause a simple irritation to a severe ulcer, and in the eyes it can cause burns and corneal or conjunctive problems. In cases of contact with sodium hydroxide, the exposed region should be placed in running water for 15 min and seek medical help. If swallowed, the victim should be given water or milk without causing vomiting, if inhaled, take the victim to an open place so he can breathe. If the victim is not breathing, artificial respiration is required.
Sodium hydroxide is a highly corrosive substance requiring strict safety measures, including immediate rinsing of skin or eyes in case of contact, using eye protection, and following SDS for specific instructions.
Explanation:Safety Procedures for Handling Sodium Hydroxide (NaOH)Sodium hydroxide (NaOH), also known as lye or caustic soda, is a white solid ionic compound that dissolves in water to form a highly basic solution. Due to its corrosive nature, safety precautions must be rigorously followed when handling NaOH in laboratory settings. Among the truths regarding sodium hydroxide and its handling are:
If NaOH is spilled on skin or clothing, the affected clothing should be removed immediately, and the skin should be rinsed extensively with water. Seeking medical attention is vital, especially if a large skin area is affected.Sodium hydroxide solutions are dangerous to the eyes, and therefore proper eye protection such as goggles must be worn at all times.Concentrated sodium hydroxide solutions can cause severe burns. Hence, concentration levels must be carefully managed, and appropriate PPE should be utilized.In the event of eye exposure, the eye should be flushed with water for at least 15 minutes, and medical help must be immediately sought.When dealing with a scenario where NaOH is inhaled, moved away from the exposure area and seek fresh air is crucial. Immediate medical attention is essential if breathing difficulties occur.
Safety data sheets (SDS) should always be closely followed for specific instructions based on different types of exposure to sodium hydroxide.
Compounds in a and b were named incorrectly. On a sheet of paper draw the molecule that fits the given description. From the structure you drew determine the correct IUPAC name. Write the correct IUPAC name in the blank.
a) 4-methyl-3-propylheptane
(I answered 4-ethyl-3-methylheptane and it was incorrect)
b) 2-ethyl-6,6,6-trimethylhexane
Answer:
a. 4—ethyl—5—methyloctane
b. 2,2,6—trimethyloctane
Explanation:Please see attachment for explanation
Imagine that you are given the mass spectra of these two compounds, but the spectra are missing the compound names.
Which peaks occur in one isomer but not the other isomer?
That is, which peaks could be used to distinguish one isomer from the other?
The structures of the isomers and the m/z values of their peaks are not given in the question. The complete question is provided in the attachment
Answer:
Compound 2 (2,5-dimethylhexane) will not have the peaks at 29 and 85 m/z
Explanation:
The fragmentation of molecules by electron ionization of mass spectrometer occurs according to Stevenson's Rule, which states that "The most probable fragmentation is the one that leaves the positive charge on the fragment with the lowest ionization energy". This is much like the Markovnikov's Rule in organic chemistry which has predicted the formation of most stable carbocation and the addition of hydrogen halide to it.
The mass spectra of compound 1 (2,4-dimethylhexane) will contain all the m/z values mentioned in the question. Each peak indicate towards homologous series of fragmentation product of the compound 1. The first peak can be attributed to ethyl carbocation (m/z = 29), with the increase of 14 units the next peak indicates towards propyl carbocation (m/z = 43) and onwards until molecular ion peak of 114 m/z.
Compound 2 (2,5-dimethylhexane) structure shows that the cleavage of C-C bond will not yield a stable ethyl and hexyl carbocation. Hence, no peaks will be observed at 29 and 85 m/z. The absence of these two peaks can be used to distinguish one isomer from the other.
If the initial concentrations of NH3(g) and H2S(g) are 2.0 M, what is the equilibrium concentration of NH3(g)?
The question is incomplete, here is the complete question:
[tex]K_c=9.7[/tex] at 900 K for the reaction [tex]NH_3(g)+H_2S(g)\rightleftharpoons NH_4HS(s)[/tex]
If the initial concentrations of [tex]NH_3(g)[/tex] and [tex]H_2S(g)[/tex] are 2.0 M, what is the equilibrium concentration of [tex]NH_3(g)[/tex] ?
Answer: The equilibrium concentration of ammonia is 0.32 M
Explanation:
We are given:
Initial concentration of ammonia = 2.0 M
Initial concentration of hydrogen sulfide = 2.0 M
For the given chemical reaction:
[tex]NH_3(g)+H_2S(g)\rightleftharpoons NH_4HS(s)[/tex]
Initial: 2.0 2.0
At eqllm: 2.0-x 2.0-x x
The expression of [tex]K_c[/tex] for above equation follows:
[tex]K_c=\frac{1}{[NH_3][H_2S]}[/tex]
The concentration of pure solids and pure liquids are taken as 1
We are given:
[tex]K_c=9.7[/tex]
Putting values in above equation, we get:
[tex]9.7=\frac{1}{(2.0-x)\times (2.0-x)}\\\\9.7x^2-38.8x+38.8=1\\\\x=2.32,1.68[/tex]
Neglecting the value of x = 1.68 because equilibrium concentration cannot be greater than initial concentration
So, equilibrium concentration of ammonia = 2 - x = (2 - 1.68) = 0.32 M
Hence, the equilibrium concentration of ammonia is 0.32 M
Without the equilibrium constant (Kc) or the actual change in concentration for NH3(g), it is not possible to calculate its equilibrium concentration from an initial 2.0 M.
Explanation:To find the equilibrium concentration of NH₃(g) given its initial concentration of 2.0 M and the additional information provided, we would typically use the equilibrium expression associated with the reaction in question.
However, the information needed to complete this calculation, such as the equilibrium constant (Kc) and the change in concentration of NH₃(g) during the reaction, has not been provided.
Using the example of the equilibrium reaction 2NH₃(g) = N₂(g) + 3H₂(g), you would set up an ICE (Initial, Change, Equilibrium) table, and use the value of Kc to solve for the equilibrium concentrations.
However, the question doesn't provide a Kc value specific to this reaction. Moreover, the example showing equilibrium concentrations of various species doesn't align with our initial concentration of 2.0 M for NH₃(g). Therefore, without the relevant Kc value or the actual changes in concentrations, we cannot solve for the equilibrium concentration of NH₃(g).
A solution was made by dissolving 25 g of potassium malonate K2C3H2O4 (MM=180.2 g/mol) in water. The total volume of that solution is 455 ml.
a) calculate the pH of that solution
b) calculate the concentration of malonic acid (H2C3H2O4) in that solution
c) what would happen to concentration of malonic acid (increase or decrease in the above solution if pH is decreased by addition of 12 M HCL?
Explain your answer using net ionic equations and Le chatelier's principle.
Answer:
a) pH = 9.8
b) 2.2 x 10⁻⁸ = [ H₂C₃H₂O₄ ]
c) decrease
Explanation:
The equilibriums involved in this question are:
C₃H₂O₄²⁻ + H₂O ⇄ HC₃H₂O₄⁻ + OH⁻ (1) Kb₁ =[HC₃H₂O₄⁻][OH⁻]/[C₃H₂O₄²⁻ ]
HC₃H₂O₄⁻ + H₂O ⇄ H₂C₃H₂O₄ +OH⁻ (2) Kb₂=[ H₂C₃H₂O₄]/[OH⁻]/[HC₃H₂O₄⁻]
The kas for malonic acid, H₂C₃H₂O₄, from reference tables are:
Ka (H₂C₃H₂O₄ )= 1.4 x 10⁻³
Ka ( HC₃H₂O₄⁻ ) = 2.0 x 10⁻⁶
a) We can calculate the Kbs for the conjugate bases of the weak malonic acid from Kw = Ka x Kb
Kb (C₃H₂O₄²⁻) = 10⁻¹⁴ / 2.0 x 10⁻⁶ =5.0 x 10⁻⁹
Kb (HC₃H₂O₄⁻)= 10⁻¹⁴ / 1.0 x 10⁻³ = 7.1 x 10⁻¹²
Given the magnitudes of the Kbs ( Kb₂ is approximately 1000 times Kb1 ) , to calculate pOh we can neglect the contribution from (2). We then treat this problem as any equilibrium:
[K₂C₃H₂O₄] = 25 g/180.2 g/mol / 0.455 L = 0.30 M
Conc C₃H₂O₄²⁻ + H₂O ⇄ HC₃H₂O₄⁻ + 0H⁻
I 0.30 0 0 0
C -x +x +x
E 0.30 - x x x
Kb (C₃H₂O₄²⁻) = [ HC₃H₂O₄⁻ ] [OH⁻]/ [ C₃H₂O₄²⁻] = x² / 0.30 - x ≅ x² /0.30
x² /.030 = 5.0 x 10⁻⁹ ⇒ x = √(0.30 x 5.0 x 10⁻⁹ ) = 7.1 x 10⁻⁵ = [ÒH⁻]
(Verifying our approximation was good 7.1 x 10⁻⁵ / 0.30 = 2.4 x 10⁻⁴ so our approximation checks)
pOH = -log 7.1 x 10⁻⁵ = 4.2
pH = 14 -4.2 = 9.8
b) To answer this part we take equilibrium (2 ) and set up our usual ICE table to solve for the concentration of malonic acid:
Conc (M) HC₃H₂O₄⁻ + H₂O ⇄ H₂C₃H₂O₄ + OH⁻ (2)
I 7.1 x 10⁻⁵ 0 0
C -x +x +x
E 7.1 x 10⁻⁵ -x x x
7.1 x 10⁻⁵ - x ≅ 7.1 x 10⁻⁵
[ H₂C₃H₂O₄ ] [OH⁻] / [HC₃H₂O₄⁻] = Kb₂ = 7.1 x 10⁻¹² = x² / 7.1 x 10⁻⁵
x = √(7.1 x 10⁻¹² x 7.1 x 10⁻⁵) = 2.2 x 10⁻⁸ = [ H₂C₃H₂O₄ ]Again our approximation checks since [HC₃H₂O₄⁻] is almost 1000 times [ H₂C₃H₂O₄ ]
c) From eqn (1) :
C₃H₂O₄²⁻ + H₂O ⇄ HC₃H₂O₄⁻ + OH⁻
The salt K₂C₃H₂O₄ will react completely with the added acid, thereby decreasing the C₃H₂O₄²⁻ concentration, and according to Le Chateliers principle the system will shift to the left and the OH⁻ at equilibrium will decrease ( as also does [HC₃H₂O₄⁻] ) therefore the pOH will increase and the pH will decrease ( less OH⁻ higher pOH, smaller pH )
Final answer:
Calculate the pH of the solution, determine the concentration of malonic acid, and explain the impact of adding HCl on the concentration of malonic acid in the solution.
Explanation:
a) Calculate the pH of the solution:
Calculate the molarity of the potassium malonate solution.
Use the dissociation of K2C3H2O4 and the autoionization of water to find the concentration of OH- ions.
Convert the OH- concentration to pH using the formula pH = 14 - pOH.
b) Calculate the concentration of malonic acid:
Set up an equilibrium expression for the dissociation of malonic acid.
Use the pH calculated in part (a) to determine the concentration of malonic acid.
c) Impact of adding HCl:
The addition of HCl will shift the equilibrium towards the formation of malonic acid, leading to an increase in its concentration.
4-hydroxypentanal reacts with one equivalent of methanol to form a cyclic acetal.
Draw curved arrows to show the movement of electrons in this step of the reaction mechanism.
Answer:
Explanation:
The equation is given as:
CH3CHOHC2H4CHO + CH3OH --> CYCLIC ACETAL + H2O
This above equation is carried out in the presence of a strong acid. There are five mechanisms employed and they are:
Step 1:
Initial formation of the hemiacetal which takes several steps
Step 2:
Addition of a proton. The hemicetal is protonated on the hydroxyl group (-OH group)
Step 3:
As seen a bond is broken to give the H2O molecule and a resonance stabilized cation.
The carbonyl group on the cation is enriched with the oxygen-18 got from the H2O molecule as seen in the mechanism.
Step 4:
An attraction occurs between electrophile and nucleophile i.e the stabilised cation and the lone paids of the methanol.
Step 5:
Finally, a proton (+) is removed from the molecule by a lone pair of electron on the methanol.
Attached are the Steps 1 - 5 mechanism below
Write the formula unit equation for this reac- tion occurring in water: Ammonium fluoride and magnesium chloride are mixed to form magnesium fluoride and ammonium chloride.
1. 2 NH4F (s) + MgCl2 (aq) → MgF2 (aq) + 2 NH4Cl (s)
2. 2 NH4F (aq) + MgCl2 (aq) → MgF2 (s) + 2 NH4Cl (aq)
3. 2 NH4F (aq) + MgCl2 (aq) → MgF2 (aq) + 2 NH4Cl (aq)
4. NH4F (aq) + MgCl (aq) → MgF (s) + NH4Cl (aq)
5. 2 NH3F (aq) + MgCl2 (aq) → MgF2 (s) + 2 NH3Cl (aq)
6. 2 NH4F (aq) + MgCl2 (s) → MgF2 (s) + 2 NH4Cl (aq)
Answer: The formula unit equation is written below.
Explanation:
Formula unit equation is defined as the balanced chemical equation that includes physical state of matter of all the compounds.
A balanced chemical equation is defined as the equation in which total number of individual atoms on the reactant side is equal to the total number of individual atoms on product side.
When ammonium fluoride reacts with magnesium chloride, it leads to the formation of ammonium chloride and a solid precipitate of magnesium fluoride.
The formula unit equation for the reaction of ammonium fluoride and magnesium chloride follows:
[tex]2NH_4F(aq.)+MgCl_2(aq.)\rightarrow MgF_2(s)+2NH_4Cl(aq.)[/tex]
This is an example of double displacement reaction.
Hence, the formula unit equation is written above.
A solution is made by dissolving 100. g of cobalt(III)chloride in 250. g of water. to make a solution that has a density of 1.25 g/mL. Calculate (I) the molality and (II) the molarity of the solution.A)(I) 2.42 m(II) 2.16 MB)(I) 2.16 m(II) 2.42 MC)(I) 0.400 m(II) 0.500 MD) (I) 0.0417 m(II) 0.0522 ME)(I) 0.0522 m(II) 0.0417 M
Answer:
Option A) (I) 2.42 m (II) 2.16 M
Explanation:
Let's determine some information.
Solute = CoCl₃ (molar mass = 165.29 g/m); mass of 100 g
Solvent = Water, mass of 250 g
Solution mass = mass of CoCl₃ + mass of water
250 g + 100 g = 350 g of solution
If we want to reach molarity (mol/L), let's determine solution volume with density:
Solution density = solution mass / solution volume
1.25 g/mL = 350 g / solution volume
Solution volume = 350 g / 1.25 g/mL = 280 mL
Let's convert the volume to L → 280 mL = 0.280L
Let's convert the mass of solute to moles = 100 g / 165.29 g/m →0.605 mol
Mol/L = 0.605 moles / 0.280 L = 2.16 M
Now let's calculate molalilty (mol/kg of solvet)
We must convert solvent mass to kg → 250g = 0.250 kg
Then, 0.605 moles / 0.250 kg =2.42 m
Final answer:
To determine the molality, divide the number of moles of CoCl₃ by the kilograms of water, resulting in a molality of 2.42 m. For the molarity, divide the moles of CoCl₃ by the volume of the solution to get a molarity of 2.16 M. Hence, the answer is option B with molality of 2.42 m and molarity of 2.16 M.
Explanation:
The question asks to calculate the molality and molarity of a cobalt(III)chloride solution. To calculate molality (m), we use the formula molality = moles of solute/kilograms of solvent. First, we need the molar mass of cobalt(III)chloride (CoCl₃), which is 165.87 g/mol. Then, we find the moles of CoCl₃ by dividing the mass of CoCl₃(100 g) by its molar mass (165.87 g/mol), which gives us approximately 0.603 moles. Molality is calculated by dividing moles of CoCl₃by the mass of water in kilograms (250 g = 0.25 kg), which yields a molality of about 2.42 m.
To calculate molarity (M), we use the formula molarity = moles of solute/volume of solution in liters. Given the density of the solution is 1.25 g/mL, we can calculate the total mass of the solution (mass of solute + mass of solvent = 100 g + 250 g = 350 g). Next, convert the total mass to volume using the density (350 g / 1.25 g/mL = 280 mL = 0.28 L). Finally, divide the number of moles of CoCl₃(0.603) by the volume of the solution (0.28 L), which results in a molarity of about 2.16 M. Therefore, the correct answer is option B: (I) 2.16 m (II) 2.42 M.
What is the minimum number of moles of sodium borohydride required to fully reduce 0.55 grams of benzophenone? Enter only the number with two significant figures.
Answer:
see explanation below
Explanation:
In this case, is pretty easy. This is a reduction reaction to form the respective alcohol.
Now for each mole of benzophenone that it's present, reacts with 1 mole of Sodium borohydryde, so, all we need to do, is to calculate the moles of benzophenone presents and these, would be the same moles of NaBH4 so:
moles Benzophenone : m/MM
The molar mass of benzophenone reported is 182.22 g/mol so:
moles Benzophenone = 0.55/182.22 = 3.02x10⁻³ moles
so the moles of NaBH₄ = 3.02x10⁻³ moles
Choose the most appropriate reagent(s) for the conversion of propyne and 2-methyl-1-tosyloxypropane to 5-methyl-2-hexyne. NaNH2, NH3 NaOH, H2O KOCH2CH3, HOCH2CH3 H2SO4 NH3
Answer:
NaNH2, NH3
Explanation:
Choose the most appropriate reagent(s) for the conversion of propyne and 2-methyl-1-tosyloxy propane to 5-methyl-2-hexyne. NaNH2, NH3 NaOH, H2O KOCH2CH3, HOCH2CH3 H2SO4 NH3
answer is NaNH2, NH3
NaNH2, NH3 is strong to to convert propyne into a nucleophilic salt which in turn displaced tosylate in 2-methyl-1-tosyloxy propane to yield 5-methyl-2-hexyne.
Propyne and 5-methyl-2-hexyne. are still of the same homologous series,, so no triple bond is broken during the reaction
The essence of a reagent is to bring the reaction to its end point
Final answer:
To convert propyne to 5-methyl-2-hexyne, sodium amide (NaNH₂) in ammonia (NH₃) is used to deprotonate propyne, creating a nucleophilic alkyne for substitution on 2-methyl-1-tosyloxypropane, ultimately forming 5-methyl-2-hexyne.
Explanation:
The conversion of propyne to 5-methyl-2-hexyne can be achieved using a strong base to deprotonate the terminal alkyne, propyne, generating a nucleophilic alkyne that can perform a substitution reaction on an alkyl halide. The most appropriate reagent for this transformation is sodium amide (NaNH₂) in ammonia (NH₃). Sodium amide is a strong base, capable of deprotonating the terminal alkyne, while ammonia acts as a solvent. Next, 2-methyl-1-tosyloxypropane would act as the alkyl halide source, where the tosylate group is a good leaving group for nucleophilic substitution by the alkynide anion created from propyne and NaNH₂. This will result in the formation of 5-methyl-2-hexyne.
Rolls of foil are 304 mmmm wide and 0.014 mmmm thick. (The density of foil is 2.7 g/cm3g/cm3 .) What maximum length of foil can be made from 1.06 kgkg of foil?
Answer:
92.2 m
Explanation:
Given that:=
The breadth = 304 mm
Height = 0.014 mm
Let Length = x mm
Volume = [tex]Length\times breadth\times height[/tex]
Thus,
Volume = [tex]304\times 0.014\times x\ mm^3=4.256x\ mm^3[/tex]
Also, 1 mm³ = 0.001 cm³
So, volume = 0.004256 cm³
Given that density = 2.7 g/cm³
Mass = 1.06 kg = 1060 g
So,
[tex]Volume=\frac{Mass}{Density}=\frac{1060}{2.7}\ cm^3=392.59\ cm^3[/tex]
So,
0.004256*x = 392.59
x = 92243.89 mm
Length of foil = 92243.89 mm = 92.2 m
A 45.30 g sample of solid mercury is initially at –59.00°C. If the sample is heated at constant pressure ( = 1 atm), kJ of heat are needed to raise the temperature of the sample to 30.00°C.
Answer:
0.165kJ
Explanation:
Formula to use for such a question is;
Energy = number of mole x molar gas constant x change in temperature
Number of mole = reacting mass of mercury / molar mass of mercury = 45.30/200.58 = 0.226moles
Change in temperature = final temperature - initial temperature = 30 - (-59) =30 + 59 = 89 Kelvin
E = nRT = 0.226 x 8.314 x 89
Energy = 165.35Joules
Energy in kJ = 165.35/1000 = 0.165kJ
Are the bonds in each of the following substances ionic, nonpolar covalent, or polar covalent?
(a) S8
(b) RbCl
(c) PF3
(d) SCl2
(e) F2(f) SF2
Answers :
Solution of each part is given below.
Explanation:
a) [tex]S_8[/tex] non polar covalent ( because each sulphur atom shares electron and the net dipole moment is zero.)
b) RbCl ionic ( Rb have good tendency to donate electron and chlorine is too electro negative therefore they make strong ionic bond.)
c) [tex]PF_3[/tex] polar covalent ( because of triagonal pyramidal geometry and strong electronegativity of F atom it is polar and covalency is due to the share of electron with each F atom.)
d) [tex]SCl_2[/tex] polar covalent ( because of tetrahedral geometry and sharing of electrons between S and Cl.)
e) [tex]F_2[/tex] non polar covalent ( because of linear geometry they are non polar and bond between them is formed due to sharing electrons.)
f) [tex]SF_3[/tex] polar covalent ( because of T- shape geometry they are non polar and due to sharing of electrons they are polar covalent.)
Hence, this is the required solution.
The nature or type of bonds formed by molecules and compounds are greatly influenced by the chemical properties of the element.
Data;
S8RbClPF3SCl2F2SF2Bonds in the CompoundsThe chemical properties of an element often affects how it bonds with other elements to form a compound. In this case, we have several compounds given.
S8: This is a non-polar covalent molecule.
RbCl: This is an ionic compound because it consists of very strong electropositive and electronegative elements.
PF3: This is a polar covalent compound due to the nature of phosphorous.
SCl2: This is a polar covalent compound
F2: This is a non-polar covalent compound
Sf3: This is a polar covalent compound
Learn more on types of bonds here;
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