Final answer:
Writing a hypothesis serves to provide a testable and falsifiable prediction that connects theoretical ideas to empirical evidence, guiding experimental design and advancing scientific understanding.
Explanation:
The purpose of writing a hypothesis is to make a testable prediction about a natural phenomenon that arises from an initial observation. By establishing a hypothesis, scientists can create a bridge between theoretical ideas and the real world, allowing them to conduct experiments and gather data.
A well-formulated hypothesis must be grounded in scientific knowledge, be logical, and most importantly, be both testable and falsifiable. This means it must be possible to design an experiment or make observations that could potentially disprove the hypothesis if it is not correct.
Scientific investigations commonly begin with an observation that leads to a question. Research and reasoning based on scientific knowledge then guide the formation of a hypothesis, often taking the form 'If condition X occurs, then effect Y will follow'.
This predictive statement is crucial for guiding the experimental design, where the objective is to either support or refute the hypothesis.
Contrary to a hypothesis, a scientific theory is a thoroughly tested and confirmed explanation for a set of observations, and a scientific law is a statement that summarizes the relationship between variables without offering the 'why' of the phenomenon.
A student is preparing to perform a series of calorimetry experiments. She first wishes to determine the calorimeter constant (Ccal) for her coffee cup calorimeter. She pours a 50.0 mL sample of water at 345 K into the calorimeter containing a 50.0 mL sample of water at 298 K. She carefully records the final temperature of the water as 317 K. What is the value of Ccal for the calorimeter? A student is preparing to perform a series of calorimetry experiments. She first wishes to determine the calorimeter constant (Ccal) for her coffee cup calorimeter. She pours a 50.0 mL sample of water at 345 K into the calorimeter containing a 50.0 mL sample of water at 298 K. She carefully records the final temperature of the water as 317 K. What is the value of Ccal for the calorimeter? 99 J/K 21 J/K 76 J/K 28 J/K 19 J/K
Answer:
First choice: 99 J/KExplanation:
1) First law of thermodynamic (energy balance)
Heat released by the the hot water (345K ) = Heat absorbedby the cold water (298 K) + Heat absorbed by the calorimeter2) Energy change of each substance:
General formula:
Heat released or absorbed = mass × Specific heat × change in temperature
density of water: you may take 0.997 g/ ml as an average density for the water.mass of water: mass = density × volume = 50.0 ml × 0.997 g/ml = 49.9 gSpecif heat of water: 1 cal / g°CHeat released by the hot water:Heat₁ = 49.9 g × 1 cal / g°C × (345 K - 317 K) = 49.9 g × 1 cal / g°C × (28K)
Heat absorbed by the cold water:Heat₂ = 49.9 g × 1 cal / g°C × (317 K - 298 K) = 49.9 g × 1 cal / g°C × (19K)
Heat absorbed by the calorimeterHeat₃ = Ccal × (317 K - 298 K) = Ccal × (19K)
4) Balance
Heat₁ = Heat₂ + Heat₃49.9 g × 1 cal / g°C × (28 K) = 49.9 g × 1 cal / g°C × (19 K) + Ccal × (19 K)
Solve for CcalCcal = [49.9 g × 1 cal / g°C × (28 K) - 49.9 g × 1 cal / g°C × (19 K) ] / 19K
Ccal = 23.6 cal/ K
Convert to cal / K to Joule / K1 cal = 4.18 Joule23.6 cal / K × 4.18 J / cal = 98.6 J/K
Which rounded to 2 signficant figures leads to 99 J/k, which is the first choice.
Calorimetry is the measurement technique, in which heat of the chemical reactions and heat capacity is measured. The value of Ccal for the calorimeter is 99 J/K.
According to the first law of thermodynamics, the energy cannot be created nor be destroyed. It can be transferred from one form to another.
Such as:
Heat released by the the hot water at 345K = Heat absorbed by the cold water at 298 K + Heat absorbed by the calorimeterAlso, from the formula, it can be calculated as:
Heat or H = mass × Specific heat × change in temperatureGiven that,
Density of water = 0.997 g/ mlMass of water = density × volume = 50.0 ml × 0.997 g/ml = 49.9 gSpecific heat = 1 cal/ g CelciusNow, substituting the values, heat released by the water will be:
Heat₁ = 49.9 g × 1 cal / g°C × (345 K - 317 K) = 49.9 g × 1 cal / g°C × (28K)Similarly, heat absorbed by the cold water will be:
Heat₂ = 49.9 g × 1 cal / g°C × (317 K - 298 K) = 49.9 g × 1 cal / g°C × (19K)Now, the overall heat absorbed by the calorimeter will be equal to:
Heat₃ = Ccal × (317 K - 298 K) = Ccal × (19K),The value of Ccal will be:
Ccal = [49.9 g × 1 cal / g°C × (28 K) - 49.9 g × 1 cal / g°C × (19 K) ] / 19K Ccal = 23.6 cal/ K or 98.6 J/K (in Joules)Therefore, the Ccal for the calorimeter will be equal to approximately 99 J/K.
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What is the kinetic theory
The body of theory which explains the physical properties of matter in terms of motion so I think it’s A
The kinetic molecular theory is an atomic description of gaseous, liquid, and solid matter. It states that these molecules are in constant, random motion with kinetic energy dependent on temperature. This theory is fundamental in explaining properties of matter including the ideal gas law.
Explanation:The kinetic molecular theory is a scientific model that explains the behavior of gases. According to this theory, gases are comprised of a large number of tiny molecules, which are widely separated and in constant, random motion. These molecules engage in elastic collisions with each other and the walls of their container. The speed of these molecules, and consequently their kinetic energy, is determined by their absolute temperatures.
This theory is also extended to explain the properties of solids and liquids in terms of continuous random motion of atoms and molecules. In other words, the kinetic molecular theory is essentially an atomic description of matter, providing detailed explanations for various phenomena such as temperature, pressure, and heat transfer, among others.
Moreover, the ideal gas law ties in closely with the kinetic molecular theory. It can be expressed in terms of the mass of the gas's molecules and the average of the molecular speeds squared.
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All faculty members are happy to see students help each other. Dumbledore is particularly pleased with Hermione. Though, it should be mentioned that students should not simply copy off each other. You will not learn anything that way. Snape glares at Ron... Ron slouches in his chair. Snape thinks it’s time for a harder problem. How many milligrams of magnesium reacts with excess HCl to produce 31.2 mL of hydrogen gas at 754 Torr and 25.0◦C. The hydrogen is produced by the following reaction: Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) Express your answer in milligrams
Answer:
[tex]m_{Mg}=30.8mgMg[/tex]
Explanation:
Hello,
Based on the given chemical reaction, as 31.2 mL of hydrogen are yielded, one computes its moles via the ideal gas equation under the stated conditions as shown below:
[tex]n_{H_2}=\frac{PV}{RT}=\frac{754torr*\frac{1atm}{760torr}*0.0312L}{0.082 \frac{atm*L}{mol*K}*298.15K}=1.27x10^{-3}molH_2[/tex]
Now, since the relationship between hydrogen and magnesium is 1 to 1, one computes its milligrams by following the shown below proportional factor development:
[tex]m_{Mg}=1.27x10^{-3}molH_2*\frac{1molMg}{1molH_2}*\frac{24.305gMg}{1molMg}*\frac{1000mgMg}{1gMg}\\m_{Mg}=30.8mgMg[/tex]
Best regards.
____________ are compounds that contain a carbon-carbon triple bond.
Answer:
Alkynes are compounds that contain a carbon-carbon triple bond.Explanation:
The simplest organic compounds are formed excluseively by carbon and hydrogen. They are named hydrocarbons.There are 3 main types of hydrocarbons, namely alkanes, alkenes and alkynes.Alkanes posses only single bonds and have general formula Cₙ H₂ₙ ₊ ₂. E.g.: CH₃ - CH₃ (ethane).Alkenes have one or more double bonds between pairs of carbon atoms. E.g.: CH₃ - CH = CH₂ (propene).Alkynes contain one or more triple bonds between pairs of carbon atoms. E.g.: CH ≡ CH (ethyne or acethylene).Both alkenes and alkynes are named unsaturated hydrocarbons, because they have less hydrogen atoms than they could (if they only hade single bonds), while alkanes are saturated hydrocarbons.At constant temperature and pressure, 2.05 g of oxygen gas O2 is added to a 1.0 L balloon containing 1.00 g of O2. What is the new volume of the balloon?
Answer:
1.50 L.
Explanation:
From the general gas law:PV = nRT,
Where, P is the pressure if the gas,
V is the volume if the gas container,
n is the no. of gas moles,
R is the general gas constant,
T is the temperature of the gas.
At constant P and T:n₁V₂ = n₂V₁.
V₁ = 1.0 L, V₂ = ??? L.
n₁ = mass/molar mass = (2.05 g)/(32.0 g/mol) = 0.064 mol.
n₂ is the no. of moles of the total gas (2.05 g + 1.0 g).n₂ = n₁ + (1.00 g)/(32.0 g/mol) = 0.0953 mol.
∴ V₂ = n₂V₁/n₁ = (0.0953 mol)(1.0 L)/(0.064 mol) = 1.489 L ≅ 1.50 L.
Which central atom hybridization would you expect in the series bh−4, ch4, nh+4?
Expected:
sp³ in all three molecules.
ExplanationThe hybridization of the central atom is related to the number of electron domains around that atom.
[tex]\begin{array}{c|c|c}\textbf{Number of Electron Domains} & \textbf{Hybridization}&\textbf{Example}\\ 2 & \text{sp} & \text{C as in CO}_2\\ 3 & \text{sp}^{2} & \text{C in H}_2\text{C}=\text{CH}_2\\ 4 &\text{sp}^{3} & \text{C as in CH}_4\end{array}[/tex].
What is an electron domain?
An atom bonded to the central atom counts as one electron domain. That atom counts as one electron domain regardless of the bond order. One single bond counts as one electron domain. One double bond counts as one electron domain. One triple bond counts as one electron domain.A lone pair of electrons count as one electron domain.How many electron domains in BH₄⁻, CH₄, and NH₄⁺?
BH₄⁻: Four H atoms are bonded to the central B atom. That ensures an octet for the central B atom. No lone pairs are needed. Four electron domains from the four bonded atoms. sp³ hybridization.CH₄: Four electrons domains with four H atoms and no lone pair. sp³ hybridization.NH₄⁺: Four electrons with four H atoms and no lone pair. sp³ hybridization.Question 2(Multiple Choice Worth 3 points)
(07.05 MC)
The table shows the concentration of a reactant in the reaction mixture over a period of time.
Reactant Concentration
Time Concentration
0 s 1.8 M
210 s 1.2 M
450 s 0.8 M
580 s 0.6 M
720 s 0.4 M
What is the average rate of the reaction over the first 580 seconds?
1.6 × 10−3
1.9 × 10−3
2.0 × 10−3
2.2 × 10−3
Answer:
2.0 × 10−3
Explanation:
this is the correct answer, i don't know why people gave the other answer 3/5 stars because that answer and work was correct.
The average rate of reaction for the first 580 seconds is 2.0 × 10−3 M/s.
What is average rate of reaction?The average rate is defined as the ratio of the change in concentration to the time taken. We are required here to find the average rate of the reaction over the first 580 seconds.
Hence, we have;
average rate = 1.8 M - 0.6 M/580 s - 0 s = 1.2 M/580 s = 2.0 × 10−3 M/s
Hence, the average rate of reaction for the first 580 seconds is 2.0 × 10−3 M/s.
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Need asap! 25 pts! Magnetic iron oxide has 72.4% iron and 27.6% oxygen. What is the empirical formula?
Hi!
1. Assume that these percentages are the mass.
2. For each of Fe and O, divide the mass by the Ar (relative atomic mass).
Fe: 72.4/55.8 = 1.297 moles
O: 27.6/16 = 1.725 moles
3. Work out which mole value is smallest, then divide the bigger mole value by the smaller one.
1.297 is smaller than 1.725, so your empirical formula is 1.1297/1.1297 = 1 atom of iron, and 1.725/1.297 = 1.33 atoms of oxygen.
4. Ensure your atom values are whole numbers.
1.33 is not a whole number, so multiply both 1 and 1.33 by 3.
5. Write out your empirical formula.
Fe3O4
Hope that helps!
The empirical formula for magnetic iron oxide, given that it has 72.4% iron and 27.6% oxygen by mass, is Fe3O4.
Explanation:The problem asks us to find the empirical formula for magnetic iron oxide. Given the percentage composition of iron and oxygen in the compound, we can look at it as if we had 100g of the substance. This would give us 72.4g of iron (Fe) and 27.6g of oxygen (O).
First, we convert these amounts to moles. The atomic mass of iron is approximately 55.845 g/mol and for oxygen is approximately 16.00 g/mol. Therefore, we have 1.3 mol Fe and 1.72 mol O.
To find the empirical formula, we divide each of these by the smallest number of moles to get a ratio. So, we have Fe1O1.3. However, an empirical formula should consist of whole numbers. Therefore, if we multiply both by the same factor, in this case, a factor of 3 will give us whole numbers, we get Fe3O4. Therefore, the empirical formula for magnetic iron oxide is Fe3O4.
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Units used to measure the rate of electron flow
an unknown element is a solid at room temperature, is highly conductive, and is easily hammered into thin sheets. it is most likely a:
A. Metal
B. Non-metal
C. Metalloid
A. Metal
Metals are very conductive, malleable, and almost all of them are solid at room temperature.
What is the ph of pure water at 40.0°c if the kw at this temperature is 2.92 × 10-14?
Answer: pH = 6.77
Explanation:
1) Chemical equilibrium
2 H₂O (l) ⇄ H₃O⁺ (aq) + OH⁻ (aq)2) Equilibrium constant, Kw
Kw = [H₃O⁺] × [OH⁻]By stoichiometry [H₃O⁺] = [OH⁻]. Call it xKw = x²x² = 2.92 × 10⁻¹⁴ M²x = √ (2.92 × 10⁻¹⁴) = 1.709 × 10⁻⁷ M = [H₃O⁺]3) pH
pH = - log [H₃O⁺] = - log (1.709 × 10⁻⁷) = 6.77The pH of pure water at 40.0°C, given an autoionization constant (Kw) of 2.92 × 10-14, would be approximately 6.768. This value is derived from using the equations Kw=[H+][OH-] for the autoionization of water and pH = -log[H+] to calculate the pH.
Explanation:The question asks about the pH of pure water at 40.0°C if the autoionization constant (Kw) at this temperature is 2.92 × 10-14. Kw is the product of the molar concentrations of H+ ions and OH- ions in water. At any given temperature, Kw remains constant. In pure water (or any neutral solution), [H+] = [OH-] and therefore, pH = pOH.
As mentioned, Kw = [H+][OH-] , so in neutral water [H+] = [OH-] = sqrt(Kw). Given that Kw is 2.92 *10^-14, we can calculate [H+] = sqrt(2.92 *10^-14) = 1.708 *10^-7 M.
The formula to find the pH is pH = -log[H+]. Substituting in, pH = -log(1.708 *10^-7) = 6.768 which is slightly on the acidic side because the ideal neutral pH in standard conditions (25°C) is 7.
This demonstrates that the pH of pure water decreases (becomes more acidic) as the temperature increases.
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which of the following would the kinetic theory address
The Kinetic Theory of gases states that the gases are made of small particles (atoms or molecules) which are in random motion.
Postulates of Kinetic Molecular Theory of gases:
1. All gases are made up of a large number of minute particles of molecules.
2. The molecules are separated from one another by large distances, called as intermolecular spaces.
3. The molecules are in the state of rapid motion in all directions. They collide with each other and the walls of the container, and thus change their directions.
4. There is no loss of energy when the molecules collide among themselves and the wall of the container.
5. The molecules are independent of each other as the molecules has no forces of interaction (repulsive or attractive) between molecules.
6. The pressure exerted by the gas is due to the collision of the molecules with the walls of the container per unit area.
7. The average Kinetic energy of the gas molecules is directly propotional to the absolute temperature.
Answer: vibrating molecules
Explanation:
a p e x
When 1,4-dimethylcyclohepta-1,3-diene is treated with hbr at elevated temperature, the 1,2-adduct predominates, rather than the 1,4-adduct. choose the correct explanation from below?
Most likely, the production of the 1,4-adduct yields a less-substituted alkene in this situation. Following the 1,2-adduct pathway ensures that the remaining double bond is stabilized by the peripheral methyl group (trisubstituted), rather than making the new double bond disubstitited.
Hope this helps!
to produce 4.00 L of a 250 mM solution of sodium hydroxide, how many grams of naOH must be dissolved?
Answer: [tex]1.56\times 10^{-3}g[/tex]
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.
[tex]Molarity=\frac{n\times 1000}{V_s}[/tex]
where,
Molarity = 250mM = [tex]250\times 10^{-3}M[/tex]
n= moles of solute
[tex]V_s[/tex] = volume of solution in ml = 4L = 4000 ml
[tex]{\text {moles of solute}}=\frac{\text {given mass}}{\text {molar mass}}=\frac{xg}{40g/mol}=0.025x[/tex]
Now put all the given values in the formula of molarity, we get
[tex]250\times 10^{-3}=\frac{0.025\times x\times 1000}{4000ml}[/tex]
[tex]250\times 10^{-3}=\frac{0.025\times x\times 1000}{4000ml}[/tex]
[tex]x=1.56\times 10^{-3}g[/tex]
Therefore, the [tex]1.56\times 10^{-3}g[/tex] of NaOH must be dissolved.
Chemistry question! Please help!
When a solid (solute) comes in contact with the liquid (solvent), the solute goes about C) dissolution, in which the solid dissolves into the liquid.
~
As this is with regards to solute and solvent, the solid will eventually dissolve in the liquid. The answer is C. dissolution.
Calculate the ph of a solution containing 0.75 m lactic acid and 0.25 m sodium lactate. recalculate after the addition of 0.05ml of hcl
pH= pKa+log[A-]/[HA]
pKa=-log(Ka)
-log(1.4/10^-4) (the Ka of lactic acid)
pKa=3.85
pH=3.85+log (0.25/.75)
pH=3.37
HCl is an acid, so the 0.05M HCl is added to the acid and subtracted from the base
pH= 3.85+ log(0.24/0.76)
pH=3.35 after addition of HCl
Atoms with an electric charge come charged by gaining or losing
Is the atoms of electric
Why will clay weather the fastest out of several types of soil?
certain types of rock, like granite, are very resistant to weathering. Igneous rocks tend to weather slowly because it is hard for water to penetrate them. Other types of rock, like limestone and marble are easily weathered because they dissolve easily in weak acids.
What is the freezing point of a solution of 0.5 mol of LiBr in 500 mL of water? (Kf = 1.86°C/m) –1.86°C –7.44°C –5.58°C –3.72°C
Answer:
Last choice: - 3.72°CExplanation:
The freezing point depression in a solvent is a colligative property: it depends on the number of solute particles.
The equation to predict the freezing point depression in a solvent is:
ΔTf = Kf × m × iWhere,
ΔTf is the freezing point depression of the solvent,m is the molality,Kf is the cryoscopic molal constant of the solvent, and i is the Van'f Hoff factor, which is the number of ions produced by each unit formula of the ionic compound.The calcualtions are in the attached pdf file. Please, open it by clicking on the image of the file.
Answer: -1.86
Explanation: Got it right on edg
anyone know how to calculate moles? for chem.
If the atmospheric pressure in the laboratory is 1.2 atm, how many moles of gas were in each syringe?
^ this is my question
Trial 1:
volume for syringe: 4.2 ml
temperature: 0.9 - C
Trial 2:
volume for syringe: 4.1 ml
temperature: 0.9 - C
if you could also explain well I would appreciate it!
Answer:
Trial 1 : n = 0.0002241 moles
Trail 2 : n = 0.0002188 moles
Explanation:
Let's bring out the data in the question;
Pressure (P) = 1.2 atm
Number of moles (n) = ?
Both trials contain different values of Volume (V) and temperature (T)
The equation that relates all four parameters (V, T, P and n) is the ideal gas equation. It is given as;
PV = nRT where R = gas constant = 0.0821 L atm K−1 mol−1
Soving for n, we have;
n = PV / RT
Trial 1
Volume (V) = 4.2 ml = 0.0042 L (Converting to L by dividing by 1000)
Temperature (T) = 0.9 + 273 = 273.9K (Converting to Kelvin temperature)
n = (1.2 * 0.0042) / (0.0821 * 273.9)
n = 0.00504 / 22.48719
n = 0.0002241 moles
Trial 2
Volume (V) = 4.1 ml = 0.0041 L (Converting to L by dividing by 1000)
Temperature (T) = 0.9 + 273 = 273.9K (Converting to Kelvin temperature)
n = (1.2 * 0.0041) / (0.0821 * 273.9)
n = 0.00492 / 22.48719
n = 0.0002188 moles
Draw the structural formula for all the alkenes with the indicated molecular formula that, without undergoing a rearrangement, produce the compound shown as a major product g
ya got to go get sum to eat then get it
How are science and technology related? A. Science is a branch of technology. B. Science is the application of technological knowledge. C. Technology is the application of the knowledge gained by science.
The answer should be C. Technology is the application of the knowledge gained by science.
Answer:
C. Technology is the application of the knowledge gained by science.
Explanation:
Science is about the discovery of some novel compounds such as cancer curing drugs or understanding the kinetics of reaction mechanisms. Technology takes the discovery made by science and upscales the process and makes it more efficient. Technology involves stem cell engineering to create clones or making pesticide resistant plants.
[Standard Enthalpy Formation]
Remember to show work and explain.
1. Use the equation below to determine the amount of energy released when 78.0g Of H2S react with excess SO2.
2. How many grams of 2AgNO3 are needed to react to produce 567kJ of energy in the following reaction?
Answer:
1. 65.1 kJ; 2. 558 g
Step-by-step explanation:
1.
M_r: 34.08
2H₂S+ SO₂ ⟶ 3S + 2H₂O ; ΔH = -56.9 kJ
Treat the heat as if it were a product in the equation. Then use the molar ratio (56.9 kJ/2 mol H₂S) in the usual way.
Moles of H₂S = 78.0 g H₂S × (1 mol H₂S/34.08 g H₂S) = 2.289 mol H₂S
Amount of heat = 2.289 mol H₂S × (56.9 kJ/2 mol H₂S) = 65.1 kJ
The reaction releases 65.1 kJ of energy.
2.
M_r: 169.87
2AgNO₃ + BaCl₂ ⟶ 2AgCl + Ba(NO₃)₂; ΔH = -345 kJ
Moles of AgNO₃ = 567 kJ × (2 mol AgNO₃/345 kJ = 3.287 mol AgNO₃
Mass of AgNO₃ = 3.287 mol AgNO₃ × (169.87 g AgNO₃/1 mol AgNO₃)
= 558 g AgNO₃
You need 558 g of AgNO₃.
For a reaction system at equlibrium, le chateliers principle can be used to predict the
According to Le Chatelier's principle, adding additional reactant to a system will shift the equilibrium to the right, towards the side of the products. ... By Le Chatelier's principle, we can predict that the amount of methanol will increase, thereby decreasing the total change in CO.
Which of the following units is used to express electrical charge? Question 2 options: Newton Coulomb Joule
The coulomb whose symbol is (C), is used to express charge. It is the SI unit of electric charge.
1 C is equivalent to charge carried by 6.24×10¹⁸ electrons. Although electrons are negatively charged, the Coulomb expresses both positive and negative charges.
Answer: Coulomb
Explanation:
[tex]Q=I\times t[/tex]
where Q= quantity of electricity
I = current in amperes
t= time in seconds
Thus charge is in coulomb. 1 coloumb of charge appears whe 1 ampere current is passed for 1 second.
Newton is the unit of force.
[tex]1kgms^{-2}=1Newton(N)[/tex]
Joule is the unit of energy.
[tex]1kgm^2s^{-2}=1 Joule[/tex]
The nucleus of an atom holds 4 neutrons and 4 protons, how many electrons does it have
Must show work for questions, if possible. (Please also explain, I don't understand)
1. A gas absorbs 0.0 J of heat and then performs 91.3 J of work. The change in internal energy of gas is
2. Two metals of equal mass with different heat capacities are subjected to the same amount of heat. Which undergoes the smallest change in temperature?
3. 30.0 mL of pure water at 280. K is mixed with 50.0 mL of pure water at 340 K. What is the final temperature?
Answers:
1. D) 91.3 J
2. A) The metal with the higher specific heat capacity
3. B) 318 K
Step-by-step explanation:
1. E, q, w
ΔE = q + w
By convention, anything leaving the system is negative and anything entering the system is positive.
q = 0.0 J
w = -91.3 J
E = 0.0 - 91.3 = -91.3 J
2. Specific heat capacity
q = mCΔT
C = q/(mΔT)
If q and m are the same for each metal, then
ΔT ∝ 1/C = k/C
As C increases, ΔT decreases.
Thus, the metal with the higher specific heat capacity will have the smaller temperature change.
3. Temperature on mixing
There are two heat flows in this problem.
Heat gained by cold water + heat lost by hot water = 0
q₁ + q₂ = 0
m₁CΔT₁ + m₂CΔT₂ = 0
m₁ΔT₁ x + m₂ΔT₂ = 0
Data:
m₁ = 30.0 g
T₁ = 280. K
m₂ = 50.0 g
T₂ = 340 K
Calculations:
ΔT₁ = T_f - Ti = T_f - T₁ = (T_f - 280.) K
ΔT₂ = T_f - Ti = T_f - T₂ = (T_f - 340) K
30.0(T_f - 280.) + 50.0(T_f - 340) = 0
30.0T_f - 8400 + 50.0T_f - 17 000 = 0
80.0T_f - 25 400 = 0
80.0T_f = 25 400
T_f =25 400/80.0
T_f = 318 K
The final temperature of the mixture is 318 K.
What does each variable stand for in PV=nRT?
Thank you.
Hello there!
Let's explain to you the different variables in the PV=nRT equation:
PV=nRT:
P = Pressure
V = Volume
n = Moles (number of moles)
R = Gas Constant (universal)
T = Temperature
This is the ideal use of the gas law.
When calculating these different variables, its units are:
P = ATM (atmospheres)
V = L (liters)
n = mol (Moles)
R = J (Joule)
T= K (Kelvin)
Rank the following elements by effective nuclear charge, Zeff, for a valence electron. F LI Be B N
F > N > B > Be > Li. This ranking is based on the decreasing effective nuclear charge (Zeff) experienced by a valence electron in the listed elements.
The element lithium (Li) has the lowest effective nuclear charge. One valence electron is 2s orbital. The nucleus has three protons (atomic number 3), however the inner electrons in the[tex]1s^2[/tex] orbital shield the valence electron, reducing its effective charge.
The Beryllium (Be) follows. The 2s orbital has two valence electrons. Despite having a higher atomic number (4) than lithium, the presence of two inner electrons in the [tex]1s^2[/tex] orbital provides more shielding and a somewhat higher effective nuclear charge.
Boron (B): Three valence electrons in the [tex]2s^2 2p^1[/tex]configuration. Boron's nucleus has more protons (atomic number 5), making it more positive. Compared to beryllium, the [tex]2p^1[/tex] electron provides less shielding for the valence electron, but the [tex]1s^2[/tex] electrons still protect the [tex]2s^2[/tex] electrons.
Nitrogen has a higher effective nuclear charge than boron. One additional proton (atomic number 7) in its nucleus boosts its positive charge. The presence of three [tex]2p^2[/tex] electrons reduces the shielding effect on the valence electron, enhancing its nucleus attraction.
Fluorine (F) has the highest effective nuclear charge. Nine protons make its nucleus extremely positively charged. Seven [tex]2p^5[/tex] electrons reduce shielding and attract the valence electron to the nucleus, resulting in the highest effective nuclear charge. Therefore, F > N > B > Be > Li is the decreasing order.
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The effective nuclear charge (Zeff) typically increases from left to right across a period in the periodic table. Therefore, for the elements F, Li, Be, B, and N, the rank order by Zeff, from lowest to highest, would be: Li < Be < B < N < F.
Explanation:The concept being asked here involves effective nuclear charge (Zeff), which highly depends on position in the periodic table. Generally, Zeff increases from left to right across a period. So, for a valence (outermost) electron in the elements you provided: F, Li, Be, B, and N, we would expect this trend to hold. The effective nuclear charge can be thought of as the net positive charge experienced by an electron in an atom. Inner electrons shield outer electrons from the full charge of the nucleus, leading to this effective reduction in charge.
Thus, using that knowledge, we can rank these elements as follows: Li < Be < B < N < F. This order means that Fluorine (F), being the furthest right on the periodic table, has the highest effective nuclear charge. The atomic nucleus of Fluorine exerts a stronger pull on its valence electron relative to the other elements that have been listed.
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Based on the kinetic molecular theory, which of the following statements is correct about the particles in a sample of gas? They have negligible kinetic energy. There is negligible force of attraction between them. The space between them decreases with increase in temperature. Their average kinetic energy decreases with increase in temperature.
Answer:
There is negligible force of attraction between them.
Explanation:
According to kinetic molecular theory of gases:
a) They have high kinetic energy so the molecules show random motion.
b) The space between them increases with increase in temperature. With increase in temperature, the kinetic energy increases and the molecules move farther from each other, volume increases.
c) the average kinetic energy increases with increase in temperature
Thus only true statement is:
There is negligible force of attraction between them.
Based on the kinetic molecular theory, there is a negligible force of attraction between the particles in the sample of gas.
The correct statement is option B.
What kinetic molecular theory?Kinetic molecular theory state that the particles of gas are large spherical and are in constant motion and have a perfectly elastic collision.
This theory can explain both Boyle's law and Charles's law.
Thus, the correct option is B, There is a negligible force of attraction between them.
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