Answer:
D. Dependent and Independent Variable
Explanation:
Since the independent variable is already the variable being changed, that is one of the things that can be changed and fromt the independent variable being changed, that changes the dependent variable.
The only things that can change in a valid experiment are dependent and independent variables.
Independent variables and independent variables:when someone is conducting an experiment, the independent variable is what they change, and the dependent variable is what changes comes because of independent variables, like the independent variable as the cause and the dependent variable as the effect.
so when one is changing the independent variable and dependent varible automatically being changed.
Therefore the correct answer is Dependent and Independent Variable (option D)
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A calorimeter contains 20.0 mL of water at 15.0 ∘C . When 1.50 g of X (a substance with a molar mass of 76.0 g/mol ) is added, it dissolves via the reaction X(s)+H2O(l)→X(aq) and the temperature of the solution increases to 25.0 ∘C . Calculate the enthalpy change, ΔH, for this reaction per mole of X. Assume that the specific heat of the resulting solution is equal to that of water [4.18 J/(g⋅∘C)], that density of water is 1.00 g/mL, and that no heat is lost to the calorimeter itself, nor to the surroundings.
Answer:
ΔH(mix'g)= 42.3Kj/mole
Explanation:
ΔH = (mcΔT)water/moles X
m = mass(g) = 20ml x 1.00g/ml = 20 g
c = 4.184 j/g⁰C
ΔT = 25°C- 15°C = 10°C
moles X = (1.5g)/(76g/mole) = 0.0197 mole X
ΔH = (20g)(4.184j/g°C)(10°C)/(0.0197 mole X) = 42,300J/mole = 42.3Kj/mole (3 sig.figs.)
The enthalpy change for the reaction per mole of substance X, which dissolves in water and increases the temperature from 15.0 °C to 25.0 °C, is calculated to be 41.8 kJ/mol. The positive sign indicates the reaction is exothermic.
Explanation:The first step is to calculate the amount of heat (q) released during the reaction. We use the formula q = mcΔT, where m is the mass of the water (density x volume = 1 g/mL x 20.0 mL = 20.0 g), c is the specific heat capacity of water (4.18 J/g⋅∘C ), and ΔT is the change in temperature (25.0 ∘C - 15.0 ∘C = 10.0 ∘C). Therefore, q = 20.0 g x 4.18 J/g⋅∘C x 10.0 ∘C = 836 J.
Next, we calculate the number of moles of X using the formula n = mass / molar mass = 1.50 g / 76.0 g/mol = 0.02 mol.
Finally, we calculate the enthalpy change (ΔH) per mole of X using the formula ΔH = q/n, therefore ΔH = 836 J / 0.02 mol = 41800 J/mol. Since the standard unit for enthalpy change is kJ/mol, we convert it from J/mol to kJ/mol by dividing by 1000 to get ΔH = 41.8 kJ/mol.
Notice that the answer is positive indicating that heat energy is released to the surroundings, which means the reaction is exothermic.
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The half-lives of unstable isotopes vary from milliseconds to billions of years
True or false
Answer:
True
Explanation:
Answer:
True
Explanation:
The half lives of unstable isotopes of elements vary from miliseconds to billions of years, for example Bismuth-209 has the longest half life known by the human and the scientists and it has still billions of years to this day, and there are elements that cannot withstand seconds before decaying into another element, so the statement is True.
A chemist needs to determine the concentration of a solution of nitric acid, HNO3. She puts 875 mL of the acid in a flask along with a few drops of indicator. She then slowly adds 0.800 M Ba(OH)2 to the flask until the solution turns pink, indicating the equivalence point of the titration. She notes that 285 mL of Ba(OH)2 was needed to reach the equivalence point. Solution map In this titration, the concentration of base is known and can be used to calculate the unknown acid concentration: concentration of base ⟶ moles of base ⟶ moles of acid ⟶ concentration of acid Part A How many moles of Ba(OH)2 are present in 285 mL of 0.800 M Ba(OH)2?
Answer:
There are 0.288 moles of Ba(OH)₂ in 285 mL of 0.800 M Ba(OH)₂Explanation:
The specific question is how many moles of Ba(OH)₂ are present in 285 mL of 0.800 M Ba(OH)₂.
In a titration, the determination of the number of moles of the substance whose molarity is known, is the first step of the calculations.
Since you know the molar concentration, and the volume of the substance, in this case the base Ba(OH)₂, you can use the molarity formula to solve for the number of moles:
The name of the variables are:
M = molarityn = number of moles of solute (Ba(OH)₂ in this case)V = volume in liters of the solutionFormula:
M = n / V (in liters) .......... [this is the definition of molarity]Solve for n:
n = M × VSubstitute the known values>
n = 0.285 liter × 0.800 M = 0.228 mole ...... keep the 3 significant figuresAnswer: 0.288 moles of Ba(OH)₂.
Note that from the number of moles of one component (the base, in this case), you can calculate the molar concentration of the other component (the acid in this case), because, at the equivalence point, both acid and base reactants are at the theoretical mole ratio, i.e. both are consumed.
Final answer:
To calculate the number of moles of Ba(OH)2 present in 285 mL of 0.800 M Ba(OH)2, multiply the volume (0.285 L) by the molarity (0.800 M), resulting in 0.228 moles of Ba(OH)2.
Explanation:
To determine the number of moles of Ba(OH)2 present in 285 mL of 0.800 M Ba(OH)2, we first convert the volume in milliliters to liters by dividing by 1000:
285 mL ÷ 1000 = 0.285 L
Now, by using the concentration of the Ba(OH)2 solution (Molarity, M), we can calculate the moles of Ba(OH)2:
Number of moles = Molarity (M) × Volume (L)
Number of moles = 0.800 M × 0.285 L
Number of moles = 0.228 moles
Therefore, there are 0.228 moles of Ba(OH)2 in the 285 mL of the solution provided by the chemist during the titration.
Mercury and oxygen react to form mercury(II) oxide, like this: 2Hg (l) + O2 (g) → 2HgO (s) At a certain temperature, a chemist finds that a 5.2L reaction vessel containing a mixture of mercury, oxygen, and mercury(II) oxide at equilibrium has the following composition: compound amount Hg 14.7g O2 13.4g HgO 17.8g calculate Kc for this reaction
Answer:
Kc = 12.4 M⁻¹
Explanation:
1) Chemical equilibrium
2Hg (l) + O₂ (g) ⇄ 2HgO (s) (the double arrow indicates an equilibrium reaction)2) Equilibrium constant, Kc:
The equilibrium constant, Kc, is equal to product of the concentrations of each product,each raised to its stoichiometric coefficient / product of the concentrations of each reactant each raised to its stoichiometric coefficient.Since the concentrations of liquid and solid substances remain practically constant, their value is incorporated into the constant Kc, and the equation only uses the concentrations of the aqueous or gaseous substances.Thus, the equation to use is:
Kc = 1 / [O₂(g) ]3) Determine the concentration of O₂ (g)
M = number of moles / volume in litersNumber of moles = mass in grams / molar massNumber of moles of O₂ (g) = 13.4 g / 32.00 g/mol = 0.419 mol M = 0.419 mol / 5.2 liter = 0.0806 mol / liter = 0.0806 M4) Compute Kc
Kc = 1 / 0.0 806 M = 12.4 M⁻¹ ← answerBoth scientists are working together to develop a model of Earth's layers in order to test their theories. They are using a Bunsen burner to represent Earth's core and vegetable oil within a large glass container to represent the asthenosphere. Given their experimental setup thus far, which of the following would be the best representation of the lithosphere
A.Water
B.Solid block of clay
C.Sand
D.Cardboard pieces
Answer:
D.Cardboard pieces
Explanation:
Cardboard pieces would a good representation of the crust.
The crust of just a thin layer in terms of thickness. We can picture the crust as an apple skin or an orange peel. It's thickness is averages about 5-10km for thinner oceanic crusts and about 30-50km for thicker continental crust.
The crust is the thinnest layer of the earth.
Below the crust is the region of the mantle. The mantle is made of the upper mantle, asthenosphere and mesosphere. The asthenosphere is in a weak plastic form and it is very thick. It averages a thickness of about 190km,about 100 times the oceanic crust and 4 times the continental crust. The mantle is the thickest region of the earth.
The core is the innermosr layer of the earth. It is about 2300km thick.
It would be very ideal to relatively represent the crust as pieces of cardboard floating on an oily asthenosphere.
Determine the pH of a HCl acid solution of 0.024
A. 0.62
B. 7.02
C. 1.62
D. 2.94
Answer:
C. 1.62.
Explanation:
∵ pH = - log[H⁺],
[H⁺] = 0.024 M.
∴ pH = - log(0.024) = 1.62.
So, the right choice is: C. 1.62.
In the reversible reaction: 2NO2 (g) ⇌ N2O4 (g) the formation of dinitrogen tetroxide releases heat and the formation of nitrogen dioxide absorbs heat. If the reaction is at equilibrium and the temperature increases, what will the effect be?
A. Nitrogen dioxide absorbs heat and changes from gas to liquid.
B. The equilibrium will shift so that there is more nitrogen dioxide.
C. The equilibrium will shift so that there is more dinitrogen tetroxide.
D. Dinitrogen tetroxide absorbs heat and changes from gas to liquid.
Answer: Option (B) is the correct answer.
Explanation:
According to Le Chatelier's principle, any disturbance causes in an equilibrium reaction will shift the equilibrium in a direction that will oppose the change.
For example, [tex]2NO_{2}(g) \rightleftharpoons N_{2}O_{4}(g)[/tex]
When we increase the temperature then the reaction will shift in a direction where there will be decrease in temperature.
This, means that the reaction will shift in the backward direction.
Thus, we can conclude that if the reaction is at equilibrium and the temperature increases, the equilibrium will shift so that there is more nitrogen dioxide.
Answer:
B. The equilibrium will shift so that there is more nitrogen dioxide.
Explanation:
Hello,
By considering that the mentioned reaction is exothermic, it means that the heat is like a product, if heat is added (increase the temperature) the equilibrium will shift leftwards, contributing to the inverse reaction; it is the formation of more nitrogen dioxide by recalling the Le Chatelier's principle.
Best regards.
You want to clean a 500.-ml flask that has been used to store a 0.900M solution. Each time the flask is emptied, 1.00 ml of solution adheres to the walls, and thus remains in the flask. For each rinse cycle, you pour 9.00 ml of solvent into the flask (to make 10.00 ml total), swirl to mix uniformly, and then empty it. What is the minimum number of such rinses necessary to reduce the residual concentration of 0.000100 M or below?
Answer:
At least four such rinses.
Explanation:
What's the concentration after each rinse?Let [tex]c_n[/tex] denotes the concentration of the residue after the [tex]n[/tex]th rinse. [tex]n[/tex] can be any non-negative integer (which includes zero.)
The initial concentration of the solution in the flask is [tex]\rm 0.900\;M[/tex]. That is:
[tex]c_0 = \rm 0.900\;M[/tex].
[tex]\rm 1.00\;mL[/tex] of this [tex]\rm 0.900\;M[/tex] solution is left in the flask after it is emptied for the first time.
The [tex]\rm 9.00\;mL[/tex] solvent will increase the volume of the solution from [tex]\rm 1.00\;mL[/tex] to [tex]\rm 10.00\;mL[/tex]. At this point the number of moles of solute in the flask stays unchanged. The concentration of the residue will drop to [tex]1/10[/tex] of the initial value. That is:
[tex]\displaystyle c_1 = \rm \frac{1}{10}\;c_0 = \frac{1}{10}\times 0.900\;M[/tex].
Repeat this process, and the concentration of the residue will drop by a factor of [tex]1/10[/tex] again. That is:
[tex]\displaystyle c_2 = \rm \frac{1}{10}\;c_1 = \frac{1}{10}\times (\frac{1}{10}\times 0.900\;M) = {\left(\frac{1}{10}\right)}^{2}\times 0.900\;M[/tex].
Summarize these values in a table:
[tex]\begin{array}{l|cccc}\text{Number of Rinses} & 0 & 1 & 2 & \dots \\[0.5em]\displaystyle\text{Concentration}\atop\displaystyle\text{of the residue}& \rm 0.900\;M & \rm\dfrac{1}{10}\times 0.900\;M &\rm {\left(\dfrac{1}{10}\right)}^{2}\times 0.900\;M \dots \end{array}[/tex].
The trend in [tex]c_{n}[/tex] is similar to that of a geometric series with
The concentration of the residue before any rinse, [tex]c_{0} = \rm 0.900\;M[/tex], andCommon ratio [tex]\displaystyle r = \frac{1}{10}[/tex].Again, refer to the trend in [tex]c_{n}[/tex] as the value of [tex]n[/tex] increases. The general formula for [tex]c_{n}[/tex], the concentration after the [tex]n[/tex]th rinse, will be:
[tex]\displaystyle c_{n} = \rm {\left(\frac{1}{10}\right)}^{n}\; 0.900\;M[/tex].
As a side note, [tex]0 < 1/10 < 1[/tex]. As a result, the value of [tex]c_{n}[/tex] will decrease but stay positive as the value of [tex]n[/tex] increases. Increasing the number of rinses will indeed reduce the concentration of the residue.
How many such rinses are required?In other words, what's the minimum value of [tex]n[/tex] for which [tex]\c_{n} \le \rm 0.000100\;M[/tex]?
Recall that
[tex]\displaystyle c_{n} = \rm {\left(\frac{1}{10}\right)}^{n}\; 0.900\;M[/tex].
As a result, [tex]n[/tex] should satisfy the condition:
[tex]\displaystyle \rm {\left(\frac{1}{10}\right)}^{n}\; 0.900\;M \le 0.000100\;M[/tex].
Multiply both sides by
[tex]\displaystyle \frac{1}{\rm 0.900\;M}[/tex],
which is positive and will not change the direction of the inequality:
[tex]\displaystyle \rm {\left(\frac{1}{10}\right)}^{n} \le \frac{0.000100}{0.900}[/tex].
Take the natural logarithm [tex]\ln[/tex] of both sides of the inequality. The function [tex]\ln(x)}[/tex] is increasing as [tex]x[/tex] increases on the range [tex]x > 0[/tex]. This function will not change the direction of the inequality, either.
[tex]\displaystyle \rm \ln\left[{\left(\frac{1}{10}\right)}^{n}\right] \le \ln\left(\frac{0.000100}{0.900}\right)[/tex].
Apply the power rule of logarithms: [tex]n[/tex] is an exponent inside the logarithm. That will be equivalent to an expression where [tex]n[/tex] is a coefficient in front of the logarithm operator:
[tex]\displaystyle \rm \ln\left[{\left(\frac{1}{10}\right)}^{n}\right] = n\cdot \left[\ln{\left(\frac{1}{10}\right)}\right][/tex].
[tex]\displaystyle n\cdot \left[\ln{\left(\frac{1}{10}\right)}\right]\le \ln\left(\frac{0.000100}{0.900}\right)[/tex].
Multiply both sides by
[tex]\displaystyle \frac{1}{\ln \left(\dfrac{1}{10}\right)}}[/tex].
Keep in mind that logarithms of numbers between 0 and 1 (excluding 0 and 1) are negative. The reciprocal of a negative number is still negative. The direction of the inequality will change. That is:
[tex]\displaystyle n\cdot \left[\ln{\left(\frac{1}{10}\right)}\right]\times \frac{1}{\ln \left(\dfrac{1}{10}\right)}}\ge \ln\left(\frac{0.000100}{0.900}\right)\times \frac{1}{\ln \left(\dfrac{1}{10}\right)}}[/tex].
The right-hand side is approximately 3.95. However, [tex]n[/tex] has to be an integer. The smallest integer that is greater than 3.95 is 4. In other words, it takes at least four such rinses to reduce the residual concentration to under 0.000100 M (0.000090 M to be precise.) Three such rinses will give only 0.00900 M.
Final answer:
Through serial dilution principles, the minimum number of rinses needed to dilute the residual concentration of a solution in a flask to 0.000100M or below is approximately 7, considering a 1:10 dilution ratio for each rinse.
Explanation:
The question involves calculating the minimum number of rinse cycles required to reduce the residual concentration of a solution adhering to the walls of a flask below a target concentration, using serial dilution principles.
After each rinse, the concentration is diluted by the volume ratio, in this case, a 1:10 dilution per rinse because 1.00 ml of the original solution is mixed with 9.00 ml of solvent. The formula for the final concentration (Cf) after n rinses is given by Cf = Co × (Vo / Vt)n, where Co is the original concentration, Vo is the original volume adhering to the flask, Vt is the total volume after adding solvent, and n is the number of rinses.
To solve for n, we rearrange the equation to get n = log(Cf/Co) / log(Vo/Vt). Plugging in the given values (Co=0.900M, Cf=0.000100M, Vo=1ml, Vt=10ml), we find that the minimum number of rinses needed to reduce the concentration to 0.000100 M or below is calculated to be around 7. The exact number might slightly vary depending on rounding during calculation, but 7 rinses ensure meeting the target concentration threshold.
What is the diameter of earth?
Answer:
12,742 km
Explanation:
Therefore, its radius is 6,371 km.
Answer:
12,742 km
Explanation:
radius is 6,371 km.
What is the total pressure of a mixture that contains 50% nitrogen at 1.7 atm, 23% oxygen at 1.1 atm, 12% argon at 0.7atm, 10% methane at 0.5 atm, and 5% water vapor at 0.2 atm?
A. 0.13 atm
B. 1.247 atm
C. 0.85 atm
D. 4.2 atm
I think so 4.2, we get the answer when we add together the pressure of each of the gases.
Answer: The total pressure of a mixture is 1.247 atm.
Explanation:
To calculate the total pressure of the mixture of the gases, we use the equation given by Raoult's law, which is:
[tex]p_T=\sum_{i=1}^n(\chi_{i}\times p_i)[/tex]
where,
[tex]p_T[/tex] = total pressure of the mixture
[tex]\chi_{i}[/tex] = mole fraction of i-th species
[tex]p_i[/tex] = partial pressure of i-th species
We are given:
For nitrogen:Mole fraction of nitrogen = 0.5
Partial pressure of nitrogen = 1.7 atm
For oxygen:Mole fraction of oxygen = 0.23
Partial pressure of oxygen = 1.1 atm
For argon:Mole fraction of argon = 0.12
Partial pressure of argon = 0.7 atm
For methane:Mole fraction of methane = 0.10
Partial pressure of methane = 0.5 atm
For water vapor:Mole fraction of water vapor = 0.05
Partial pressure of water vapor = 0.2 atm
Putting values in above equation, we get:
[tex]p_T=[(0.5\times 1.7)+(0.23\times 1.1)+(0.12\times 0.7)+(0.10\times 0.5)+(0.05\times 0.2)][/tex]
[tex]p_T=1.247atm[/tex]
Hence, the total pressure of a mixture is 1.247 atm.
What is the overall equation for this chemical reaction?
The overall reaction for the chemical equation in question can be obtained by balancing the equation. The initial equation C2H6 + 7/2O2 → 3H2O + 2CO2 is balanced by multiplying the coefficients by 2 to obtain: 2C2H6 + 7O2 → 6H2O + 4CO2. This represents the overall homogeneous reaction indicating the rate of consumption of reactants and formation of products.
Explanation:In the realm of Chemistry, the overall reaction for the given chemicals is derived by multiplying each coefficient in the equation by 2, resulting in a balanced equation. Starting with the equation C₂H₆ + 7/2O₂ which leads to 3H₂O + 2CO2, multiplying the coefficients by 2 gives us: 2C₂H₆ + 7O₂ --> 6H₂O + 4CO2. This equation represents the overall reaction observed. It may also depict an elementary reaction showing first-order behavior. The overall reaction equation reflects the stoichiometry of this homogeneous reaction, signaling rates for the consumption of reactants and the formation of products.
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Electrons are ejected from a surface with speeds ranging up to 1380 km/s when light with a wavelength of 173 nm is used. What is the work function of this surface? The speed of light is 2.99792 × 108 m/s and Planck’s constant is 6.62607 × 10−34 J · s. Answer in units of eV.
Answer:
ΔE(work)= 692 Kj/mole e⁻ = 4.32 x 10²⁴ eV/mole e⁻
Explanation:
ΔE = hc/λ = (6.63 x 10⁻³⁴j·s)(2.99792 x 10⁸m/s)/(1.73 x 10⁻⁷m) = 1.15 x 10⁻¹⁸j/e⁻ x 6.023 x 10²³ e⁻/mole = 691,999 j/mole e⁻ = 692 Kj/mole e⁻ x 6.24 x 10²¹ eV/KJ = 4.32 x 10²⁴ eV/mole e⁻
What does it mean when a mineral has a definite chemical composition?
Answer:
For a substance to classify as a mineral, it must lie within certain parameters. It should be an inorganic solid, that is naturally occurring in nature (not synthesized), with an ordered internal structure and a definite chemical composition.
By definite chemical composition, geologists mean that the mineral must be have chemical constituents that have an unvarying chemical composition, or a chemical composition that oscillates withing a very limited and specific range.
An example is the mineral, halite. It has a chemical composition of one sodium atom and one chloride atom, represented as NaCl and is unchanging in this composition throughout nature.
Hope this helpsHow are energy and work related?
O
A. Work and energy are the same.
B. Energy is the capacity to do work.
C. Energy is the force needed to do work.
D. Work times energy is force.
Answer:
B
Explanation:
When work is done, energy is transferred between systems, or transformed from one type of energy into another type. Energy shares the same units of measure as work.
Work and energy are directly related in physics - the amount of work done is the same as the energy transferred. Energy can be defined as the capacity to do work.
Explanation:Work and energy are directly related concepts in physics. The amount of work done is equivalent to the amount of energy transferred. This is because, by definition, work is done when a force acts on an object to move it some distance, and this process requires energy. Therefore, energy can be viewed as the capacity to do work. If an entity does not contain energy, it cannot perform work. This concept is fundamental to understanding the physics of energy transfer and conservation.
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Chlorine has two stable isotopes, Cl-35 and Cl-37. If their exact masses are 34.9689 amu and 36.9695 amu, respectively, what is the natural abundance of Cl-35? (The atomic mass of chlorine is 35.45 amu)a) 75.95%b) 24.05%c) 50.00%d) 35.00%e) 37.00%
Final answer:
The natural abundance of Cl-35 is found by solving for the fraction x in the average atomic mass equation, which corresponds to the percentage. The solution shows that the natural abundance of Cl-35 is 75.77%.
Explanation:
The question is asking us to determine the natural abundance of Cl-35 given the average atomic mass of chlorine and the exact masses of its two stable isotopes, Cl-35 and Cl-37. To find this, we can use the formula for calculating the average atomic mass:
Average atomic mass = (fraction of isotope 1 × mass of isotope 1) + (fraction of isotope 2 × mass of isotope 2)
Let x be the fraction of Cl-35 and (1-x) the fraction of Cl-37. Since the percentages must add up to 100, we have:
35.45 amu = (x × 34.9689 amu) + [(1 - x) × 36.9695 amu]
Rearrange to solve for x:
x = (35.45 - 36.9695) / (34.9689 - 36.9695)
Calculate x and then convert x to a percentage:
x × 100 = percent abundance of Cl-35
Using x = 0.7577 (from given information), we find:
Percent abundance of Cl-35 = 0.7577 × 100 = 75.77%
Therefore, the natural abundance of Cl-35 is 75.77%.
How does the addition of salt to solid ice affect the melting transition from solid to liquid?
A. The amount of energy absorbed would not change during the plateau.
B. It would need to absorb less energy during the plateau in order to melt.
C. It would need to absorb more energy during the plateau in order to melt.
D. There would be no plateau, the salt would cause the solid to immediately melt.
The water would need to B. absorb less energy during the plateau in order to melt.
Explanation:Salt when added to ice lowers the freezing point of the ice. So, if ice is added to the solid ice it doesn't let it to freeze rather the temperature of water may fall but it won't freeze.
For melting, it needs less energy after adding salt because salt itself absorbs the energy from the surroundings to help the phase transition of water from solid to liquid.
Answer: C. It would need to absorb more energy during the plateau in order to melt.
Explanation:
adding salt lowers the freezing point, meaning it needs to absorb more energy from its surrounding in order to melt.
Which value is MOST likely to be the boiling point of the substance at this constant pressure?
Answer:
48 c
Explanation:
its b on usa test prep
How to apply Raoult's law to real solutions Consider mixing a liquid with a vapor pressure of 100 torr with an equimolar amount of a liquid with a vapor pressure of 200 torr. The resulting solution would be predicted to have a vapor pressure of 150 torr if it behaved ideally. If, however, the interactions between the different components are not similar we can see positive or negative deviations from the calculated vapor pressure. An actual vapor pressure greater than that predicted by Raoult's law is said to be a positive deviation and an actual vapor pressure lower than that predicted by Raoult's law is a negative deviation. Part A Imagine a solution of two liquids in which the molecules interact less favorably than they do in the individual liquids. Will this solution deviate positively from, deviate negatively from, or ideally follow Raoult's law?'
Answer:
[tex]\boxed{\text{positive deviation}}[/tex]
Explanation:
[tex]\text{If the molecules interact less favourably in the solution than in the individual}\\\text{liquids, they can break away more easily than they can in the separate liquids.}\\\text{There will be more molecules in the vapour phase than you would expect.}\\\text{The solution will show a } \boxed{\textbf{positive deviation}} \text{ from Raoult's Law.}[/tex]
What is the pressure of 1.9 mols of nitrogen gas in a 9.45 L tank and at a temperature of 228 K
Answer:
P = 3.8 Atm = 2900 mmHg (2 sig.figs.)
Explanation:
PV = nRT => P = nRT/V = (1.9 moles)(0.08206LAtm/molK)(228K)/9.45L = 3.76 ~ 3.8 Atm x 760mmHg/Atm =2888 mmHg ~ 2900 mmHg (2 sig.figs.)
2900 mmHg is the pressure of 1.9 mols of nitrogen gas in a 9.45 L tank and at a temperature of 228 K.
What is pressure?"Pressure" is defined as the thrust (force) applied to a surface per area. The force to area ratio is another way to describe it (over which the force is acting). The height of a mercury column that precisely balanced the mass of the columns of atmosphere above the barometer is used to measure atmospheric pressure, which is also referred to as barometric pressure.
It can be stated using a number of various measurement methods, including millimeters (or inches) of mercury, pounds every square inch (psi), dynes per square centimeter (dyn/sq cm), millibars (mb), standard atmospheres, as well as kilopascals.
PV = nRT
P = nRT/V
(1.9 moles)(0.08206LAtm/molK)(228K)/9.45L = 3.76
3.8 Atm x 760mmHg/Atm =2888 mmHg
=2900 mmHg
Therefore, the pressure is 2900 mmHg.
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How many molecules of sodium oxide will be created if 187 grams of oxygen reacts with excess sodium? 4Na + O2 -> 2Na2O A. 11.69 x 1023 molecules of Na2O
To determine the number of molecules of sodium oxide created, we can use the given balanced chemical equation, molar mass, and Avogadro's number. The reaction equation tells us that for every 4 moles of sodium, 2 moles of sodium oxide are formed. From the given mass of oxygen, we can calculate the number of moles of sodium oxide and then convert that to molecules using Avogadro's number.
Explanation:To determine the number of molecules of sodium oxide created, we need to use the given balanced chemical equation and the molar mass of sodium oxide (Na2O). From the balanced equation, we can see that 4 moles of sodium (Na) react with 1 mole of oxygen (O2) to form 2 moles of sodium oxide (Na2O). Thus, the stoichiometry of the reaction tells us that for every 4 moles of sodium, 2 moles of sodium oxide are formed.
Using the molar mass of sodium oxide, which is 61.98 grams/mol, we can calculate the number of moles of sodium oxide formed from the given mass of oxygen. First, convert the mass of oxygen to moles by dividing it by the molar mass of oxygen, which is 32.0 grams/mol. So, 187 grams of oxygen is equal to 5.84 moles. Based on the stoichiometry of the reaction, for every 1 mole of oxygen, 2 moles of sodium oxide are formed. Therefore, 5.84 moles of oxygen will form 11.68 moles of sodium oxide.
Finally, to determine the number of molecules of sodium oxide, we can use Avogadro's number, which states that 1 mole of any substance contains 6.02 x 10^23 particles (atoms or molecules). So, multiplying the number of moles of sodium oxide by Avogadro's number, we get:
11.68 moles x 6.02 x 10^23 molecules/mol = 7.03 x 10^24 molecules of Na2O
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Addition of _____________ to pure water causes the least increase in conductivity. A) weak bases B) acetic acid C) ionic compounds D) organic molecules
Organic molecules cause the least increase in conductivity when added to pure water, as they do not dissociate into ions, unlike ionic compounds which dissociate completely, and weak acids and bases which partially ionize.
The addition of organic molecules to pure water causes the least increase in conductivity. This is because organic molecules typically do not dissociate into ions when dissolved in water. On the other hand, ionic compounds dissociate almost completely in water, making them strong electrolytes and significantly increasing water's conductivity. Option D is correct .
Weak bases and acetic acid, a weak acid, only partially ionize in water, which would lead to a slight increase in conductivity compared to organic molecules, but much less than that caused by ionic compounds.
The weak bases mentioned do not refer to the dissociation of ionic compounds themselves but to the reactions of their polyatomic anions with water. Thus, when discussing weak bases in this context, it is important to consider these secondary reactions rather than primary dissociation.
Furthermore, acetic acid, being a weak acid, increases the hydronium ion concentration in water, but again not as much as a strong acid would. However, since both acetic acid and weak bases only partially ionize, they’re still considered weak electrolytes.
Iron (III) oxide, also known as rust can be removed from iron by reacting it with hydrochloric acid to produce iron (III) chloride and water. Fe2O3 (s) + 6HCl (aq) ---> 2FeCl3 + 3H2O (l) What mass of hydrogen chloride is required to react with 100 g of rust? a. 371g HCl b. 137g HCl c. 130g HCl d. 147g HCl
Answer:
b. 137 g.
Explanation:
The balanced equation for the mentioned reaction is:Fe₂O₃(s) + 6HCl(aq) → 2FeCl₃(s) + 3H₂O(l),
It is clear that 1.0 mole of Fe₂O₃ react with 6.0 mol of HCl to produce 2.0 moles of FeCl₃ and 3.0 moles of H₂O.
We need to calculate the no. of moles of rust (100.0 g):n = mass/molar mass = (100.0 g)/(159.69 g/mol) = 0.6262 mol.
Using cross multiplication:
1.0 mol of Fe₂O₃ react completely with → 6.0 mol of HCl, from stichiometry.
0.6262 mol of Fe₂O₃ produced with → ??? mol of HCl.
∴ The no. of moles of HCl = (6.0 mol)(0.6262 mol)/(1.0 mol) = 3.757 mol.
∴ The mass of HCl needed = no. of moles x molar mass = (3.757 mol)(36.46 g/mol) = 137.0 g.
So, the right choice is: b. 137 g.
To find the required mass of HCl to react with 100 g of rust, calculate the moles of rust, use the stoichiometry of the reaction to find moles of HCl needed, and then convert those moles to grams. The answer is approximately 137 g of HCl.
Explanation:To determine the mass of hydrochloric acid (HCl) required to react with 100 g of rust (iron (III) oxide, Fe₂O₃), we use stoichiometry based on the balanced chemical equation: Fe₂O₃ (s) + 6HCl (aq) → 2FeCl₃ (aq) + 3H₂O (l).
First, calculate the molar mass of Fe₂O₃ (55.85 g/mol for Fe and 16.00 g/mol for O):
2(55.85) + 3(16.00) = 159.70 g/mol.
Next, calculate the moles of Fe₂O₃ in 100 g:
100 g ÷ 159.70 g/mol = 0.626 moles of Fe₂O₃.
According to the equation, 1 mole of Fe₂O₃ reacts with 6 moles of HCl. Therefore, 0.626 moles of Fe₂O₃3 will react with 0.626 * 6 = 3.756 moles of HCl.
Molar mass of HCl = 36.46 g/mol, so the mass of HCl needed is:
3.756 moles * 36.46 g/mol = 136.93 g, or approximately 137 g.
Thus, option (b) 137 g HCl is the correct answer for the mass of HCl required to react with 100 g of rust.
Using the ideas from this section and the periodic table, choose the more reactive metal
K or Cu
Answer: K
Hope this helps you out!
Answer:
Potassium (K)
Explanation:
The reason that potassium is the more reactive metal is because it is in group 1, as opposed to group 11 for copper, and being in group 1 means that it has one valence electron, which it can give away by reacting with almost any other element, and in doing so, it becomes much more stable.
What was one main point of Dalton's atomic theory?
O
A. That atoms were made up of positive and negative charges
B. That atoms had a nucleus at the center
C. That atoms made up the smallest form of matter
O
D. That atoms changed as they formed compounds
Answer:
C. That atoms made up the smallest form of matter
Explanation:
The crux of the Dalton's atomic theory is that atoms are the smallest form of matter. He propositioned that atoms is an indivisible particle and beyond an atom, no form of matter exists.
Series of discoveries through time have greatly shaped the Dalton's atomic theory. The discovery of cathode rays by J.J Thomson in 1897 opened up the atom. Atoms were now seen to be made up of some negatively charged particles. Ernest Rutherford through his gold foil experiment proposed the nuclear model of the atom.
Atom X has 50 nucleons and a binding energy of 4.2 10^11 J. Atom Z has 80 nucleons and a binding energy of 8.4 10^11 J. Which atom has the greater binding energy per nucleon?
Answer:
E(Z) > E(X)
Explanation:
X => 4.2 x 10¹¹J/50 Nucleons = 8.4 x 10⁹ J/Nu
Z => 8.4 x 10¹¹J/80 Nucleons = 1.1 x 10¹⁰ J/Nu
E(Z)1.1 x 10¹¹J/Nu > E(X)8.4 x 10⁹J/Nu
A) The breaking of chemical bonds
B) physical changes in Atoms
C) Chemical reactions
D) The nuclei of unstable isotopes
Question, where does radioactivity come from?
Answer:
D) The nuclei of unstable isotopes
Explanation:
For example, the carbon-14 in carbon dating is radioactive.
When it decays, a neutron in the nucleus is converted into a proton, an electron, and an antineutrino.
[tex]_{0}^{1}\text{n} \longrightarrow \, _{1}^{1}\text{p} + \, _{-1}^{0}\text{e} + \overline{\nu}_{\text{e}}[/tex]
What is the ratio of molecules in:
CH4 + 2O2 -> CO2 + 2H2O
Answer:
1:2:1:2
Explanation:
A molecule is made up of aggregates of small particles called atoms.
CH₄ + 2O₂ → CO₂ + 2H₂O
From the reaction above we have: 1 molecule of methane CH₄ reacting with 2 molecules of oxygen gas O₂ to produce 1 molecule of carbon dioxide gas CO₂ and 2 molecules of H₂O:
CH₄ + 2O₂ → CO₂ + 2H₂O
1 : 2 : 1 : 2
Sodium hydrogen carbonate NaHCO3 , also known as sodium bicarbonate or "baking soda", can be used to relieve acid indigestion. Acid indigestion is the burning sensation you get in your stomach when it contains too much hydrochloric acid HCl , which the stomach secretes to help digest food. Drinking a glass of water containing dissolved NaHCO3 neutralizes excess HCl through this reaction: HCl (aq) + NaHCO3 (aq) → NaCl (aq) + H2O (l) + CO2 (g) The CO2 gas produced is what makes you burp after drinking the solution. Suppose the fluid in the stomach of a man suffering from indigestion can be considered to be 200.mL of a 0.012 M HCl solution. What mass of NaHCO3 would he need to ingest to neutralize this much HCl ? Round your answer to 2 significant digits.
Answer:
[tex]\boxed{\text{0.20 g}}[/tex]
Explanation:
We know we will need a balanced chemical equation with molar masses, volumes, and concentrations, so, let's gather all the information in one place.
M_r: 84.01
HCl + NaHCO₃ ⟶ NaCl + H₂O + CO₂
V/mL: 200.
c/mol·L⁻¹: 0.012
(a) Moles of HCl
[tex]\text{Moles of HCl} =\text{0.200 L HCl} \times \dfrac{\text{0.012 mol HCl}}{\text{1 L HCl}}\\\\=\text{0.0024 mol HCl}[/tex]
(b) Moles of NaHCO₃
The molar ratio is 1 mol NaHCO₃ = 1 mol HCl
[tex]\text{Moles of NaHCO$_{3}$}= \text{0.0024 mol HCl} \times \dfrac{\text{1 mol {NaHCO$_{3}$}}}{ \text{1 mol HCl}}\\\\= \text{0.0024 mol NaHCO$_{3}$}[/tex]
(c) Mass of NaHCO₃
[tex]\text{Mass of NaHCO$_{3}$}= \text{0.0024 mol NaHCO$_{3}$} \times \dfrac{\text{84.01 g {NaHCO$_{3}$}}}{ \text{1 mol NaHCO$_{3}$}}\\\\= \textbf{0.20 g NaHCO$_{3}$}\\\\\text{The man would need to ingest }\boxed{\textbf{0.20 g}} \text{ of NaHCO$_{3}$}.[/tex]
Which of the following set of quantum numbers (ordered n, ℓ, mℓ, ms) are possible for an electron in an atom? Check all that apply. View Available Hint(s) Hint 1. How to approach the problem Hint 2. Identify issues with an example set of quantum numbers opened hint Check all that apply. 4, 2, 3, -1/2 2, 1, 0, 1 3, 1, 0, -1/2 4, 3, -2, 1/2 -3, 2, 2, -1/2 4, 2, -1, -1/2 2, 2, 2, 1/2 3, 2, -3, 1/2
Each of the four quantum numbers for an electron in an atom represents a specific characteristic and has specific rules regarding which values are allowed. The principal quantum number n can be any positive integer, the azimuthal quantum number l ranges from 0 to n - 1, the magnetic quantum number ml ranges from -l to +l, and the spin quantum number ms can either be +1/2 or -1/2. The quantum numbers 2, 1, 0, 1; 3, 1, 0, -1/2; 4, 2, -1, -1/2 from the provided list are valid.
Explanation:To evaluate the possible set of quantum numbers, it is important to understand the rules that govern the values for each quantum number. The quantum numbers are expressed in the form (n, ℓ, mℓ, ms). Each one of these represents a certain feature of a given electron in an atom.
The first quantum number n, known as the principal quantum number, denotes the electron's energy level and can be any positive integer starting from 1.
The second quantum number ℓ, known as the azimuthal or angular momentum quantum number, is responsible for the shape of the electron's orbital and can have values ranging from 0 to n - 1.
The third quantum number, mℓ, known as the magnetic quantum number, describes the orientation of the electron's orbital. It can have values between -ℓ and +ℓ including 0.
Lastly, the fourth quantum number ms, the electron spin quantum number, can have one of two values: +1/2 or -1/2, denoting the two possible spin states of an electron.
Using these rules, we can verify the following quantum numbers: 4, 2, 3, -1/2, 2, 1, 0, 1, 3, 1, 0, -1/2, 4, 3, -2, 1/2, -3, 2, 2, -1/2, 4, 2, -1, -1/2, 2, 2, 2, 1/2, 3, 2, -3, 1/2. It is evident the following quantum numbers are valid: 2, 1, 0, 1; 3, 1, 0, -1/2; 4, 2, -1, -1/2.
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Hydrogen sulfide gas (H2S) is a highly toxic gas that is responsible for the smell of rotten eggs. The volume of a container of hydrogen sulfide is 44.2mL. After the addition of more hydrogen sulfide, the volume increases to 98.5mL under constant pressure and temperature. The container now holds 1.97×10−3mol of the gas. How many grams of hydrogen sulfide were in the container initially? Give your answer in three significant figures.
Answer:
[tex]\boxed{\text{0.0301 g}}[/tex]
Step-by-step explanation:
1. Calculate the initial moles of H₂S
We can use Avogadro's law: the number of moles of a gas is directly proportional to the volume if the pressure and temperature are constant.
[tex]\dfrac{n_{1} }{V_{1}} = \dfrac{n_{2}}{V_{2}}\\\\\dfrac{n_{1}}{\text{44.2 mL}} = \dfrac{1.97 \times 10^{-3} \text{ mol}}{\text{98.5 mL }}\\\\\dfrac{n_{1}}{44.2} = 2.00 \times 10^{-5} \text{ mol}\\\\n_{1} = 44.2 \times 2.00 \times 10^{-5} \text{ mol} = 8.84 \times 10^{-4} \text{ mol}[/tex]
2. Calculate the initial mass of H₂S
[tex]\text{Mass of H$_{2}$S} = 8.84 \times 10^{-4}\text{ mol H$_{2}$S} \times \dfrac{\text{34.08 g H$_{2}$S}}{\text{1 mol H$_{2}$S}} = \text{0.0301 g H$_{2}$S}\\\\\text{The container initially held }\boxed{\textbf{0.0301 g H$_{2}$S}}[/tex]