Question 1

Sodium hydroxide is available commercially as a 50.0% by weight aqueous solution.The density of the solution is 1.53 g/mL.Calculate the molarity of this sodium hydroxide solution.
A)0.450 M
B)19.1 M
C)25.0 M
D)125.M

Accepted Answer

Molarity (M) is defined as moles of solute per liter of solution.

To calculate the molarity of the sodium hydroxide solution, we need to first find the number of moles of NaOH in 1 liter of solution.

Since the solution is 50.0% by weight, we know that 1 L of the solution contains:

- mass of NaOH = 0.5 x 1000 mL x 1.53 g/mL = 765 g
- number of moles of NaOH = mass / molar mass = 765 g / 40.00 g/mol = 19.125 mol

Therefore, the molarity of the solution is:

M = number of moles / volume of solution = 19.125 mol / 1 L = 19.1 M

So, the correct answer is B.

Question 2

Which of the following statements is true for a supersaturated solution?
A)The solute in the solution is at equilibrium with undissolved solute.
B)The solution contains more than the equilibrium amount of solute.
C)The solution is stable and the solute will not precipitate.
D)A supersaturated solution is more than 50% solute by mass.

Accepted Answer

A supersaturated solution contains more solute than what is in equilibrium with the solvent at that temperature and pressure. This means that the solution is unstable and the excess solute may precipitate out under certain conditions.

Question 3

A solution of LiCl in water has X_LiCl = 0.0400.What is the molality? A)4.16 m LiCl B)2.22 m LiCl C)2.31 m LiCl D)4.21 m LiCl

Accepted Answer

X_LiCl represents the mole fraction of LiCl in the solution. Therefore, we can use the formula: molality = moles of solute / mass of solvent in kg To calculate the moles of solute, we can assume that we have 1 kg of water, as X_LiCl is a mole fraction. moles of LiCl = X_LiCl * mass of water / molar mass of LiCl moles of LiCl = 0.0400 * 1000 g / 42.39 g/mol (molar mass of LiCl) moles of LiCl = 0.944 mol molality = 0.944 mol / 1 kg = 0.944 m Therefore, the molality is 2.31 m LiCl, which is choice C.

Question 4

The solubility of argon in water at 25°C is 0.0150 mol/L.What is the Henry's Law constant for argon if the partial pressure of argon in air is 0.00934 atm? A)1.40 × 10^-4 mol/(L ∙ atm) B)0.623 mol/(L ∙ atm) C)1.61 mol/(L ∙ atm) D)4.10 mol/(L ∙ atm)

Accepted Answer

Henry's Law states that the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. The equation for Henry's Law is:

C = kH * P

where C is the concentration of the gas in the liquid, P is the partial pressure of the gas above the liquid, and kH is the Henry's Law constant.

To find kH for argon, we can rearrange the equation to:

kH = C / P

Substituting the given values, we get:

kH = 0.0150 mol/L / 0.00934 atm

kH = 1.61 mol/(L ∙ atm)

Therefore, the correct answer is C.

Question 5

The solubility of gaseous solutes in liquid solvents is greater when the
A)external pressure over the solution is increased.
B)external pressure is decreased.
C)partial pressure of the gas above the solution is increased.
D)partial pressure of the solvent is increased.

Accepted Answer

The solubility of gaseous solutes in liquid solvents is directly proportional to the partial pressure of the gas above the solution. When the partial pressure of gas is increased, more gas molecules will dissolve in the liquid solvent, resulting in higher solubility. Decreasing external pressure or increasing the pressure of the solvent has no significant effect on the solubility of gaseous solutes.

Question 6

At a given temperature the vapor pressures of benzene and toluene are 183 mm Hg and 59.2 mm Hg,respectively.Calculate the mole fraction of benzene in the vapor phase over a solution of benzene and toluene with X_benzene = 0.600. A)0.600 B)0.678 C)0.756 D)0.823

Accepted Answer

The answer of At a given temperature the vapor pressures...

Question 7

Aqueous solutions of 30.0% (by weight)hydrogen peroxide,H₂O₂,are used to oxidize metals or organic molecules in chemical reactions.Calculate the molality of this solution. A)0.974 m B)6.78 m C)9.79 m D)12.6 m

Accepted Answer

The answer of Aqueous solutions of 30.0% (by weight)hydrogen peroxide,H₂O₂,are...

Question 8

At 25.0°C,a solution has a concentration of 3.179 M and a density of 1.260 g/mL.The density of the solution at 50.0°C is 1.249 g/mL.What is the molarity of the solution at 50.0°C?
A)2.545 M
B)3.151 M
C)3.179 M
D)3.230 M

Accepted Answer

As temperature increases, the volume of the solution increases due to thermal expansion, leading to a decrease in molarity. The density change from 1.260 g/mL to 1.249 g/mL indicates this expansion. Using the formula for molarity change with volume, the molarity at 50.0°C is approximately 3.151 M.

Question 9

In general,as the temperature increases,the solubility of gases in water ________ and the solubility of most solids in water ________.
A)decreases,decreases
B)decreases,increases
C)increases,decreases
D)increases,increases

Accepted Answer

The solubility of gases in water decreases with an increase in temperature, while the solubility of most solids in water increases with an increase in temperature.

Question 10

Which of the following aqueous salt (NaCl)solutions has the greater concentration?
A)0.5 M
B)2.3 m
C)3.0 % by mass
D)11.1 g/L

Accepted Answer

Molarity (M) is defined as the number of moles of solute per liter of solution. Therefore, the higher the molarity, the greater the concentration.

Option A has a lower molarity of 0.5 M.

Option B has a higher molarity of 2.3 M, so it has the greater concentration of the two options.

Option C is given as the percentage by mass, which is not the same as molarity, and therefore cannot be compared directly.

Option D is given as the concentration in grams per liter, which can be converted to molarity by dividing by the molar mass of NaCl (58.44 g/mol). Doing this calculation, we get a molarity of 0.19 M, which is lower than option B.

Question 11

A 3.17 m solution of CaCl₂ in water has a density of 1.24 g/mL.What is the molarity? A)2.56 M CaCl₂ B)2.91 M CaCl₂ C)3.50 M CaCl₂ D)3.93 M CaCl₂

Accepted Answer

To find molarity, use the formula: Molarity = (molality * density * 1000) / (1 + molality * molar mass of solute). Here, molality is 3.17 m, density is 1.24 g/mL, and the molar mass of CaCl2 is 110.98 g/mol. Calculating gives approximately 2.91 M.

Question 12

Aqueous solutions of 30% (by weight)hydrogen peroxide,H₂O₂,are used to oxidize metals or organic molecules in chemical reactions.Given that the density of the solution is 1.11 g/mL,calculate the molarity. A)0.794 M B)6.78 M C)9.79 M D)12.6 M

Accepted Answer

To calculate the molarity of a solution, we need to know the number of moles of solute (in this case, hydrogen peroxide) per liter of solution.

First, we need to convert the percentage by weight to grams of hydrogen peroxide per 100 grams of solution:

30 g H2O2 / 100 g solution

Next, we need to use the density to convert the volume of the solution to mass:

1 mL solution x 1.11 g/mL = 1.11 g solution

Now we can calculate the number of moles of hydrogen peroxide:

30 g H2O2 / 34.01 g/mol = 0.882 moles H2O2

Finally, we can calculate the molarity:

0.882 moles H2O2 / 0.090 L solution = 9.79 M

Therefore, the correct answer is C (9.79 M).

Question 13

A solution is prepared by dissolving 20.0 g of sucrose,C₁₂H₂₂O₁₁,in 250.g of water at 25°C.What is the vapor pressure of the solution if the vapor pressure of water at 25°C is 23.76 mm Hg? A)0.198 mm Hg B)20.5 mm Hg C)23.7 mm Hg D)24.0 mm Hg

Accepted Answer

The answer of A solution is prepared by dissolving 20.0...

Question 14

A solution of LiCl in water is 9.00 wt% LiCl.What is the mole fraction of LiCl?
A)0.0407
B)0.0466
C)0.212
D)2.28

Accepted Answer

The mole fraction is calculated by dividing the moles of LiCl by the total moles of the solution. For 9.00 wt% LiCl, the moles of LiCl and water are calculated, and the mole fraction of LiCl is approximately 0.0407.

Question 15

Which of the following is not an application of colligative properties?
A)adding silver to mercury to lower the vapor pressure of mercury
B)desalinating sea water by reverse osmosis
C)melting snow by application of salt
D)reduced boiling points of pure liquids at increased altitudes

Accepted Answer

Colligative properties depend on the number of particles in a solution and include phenomena such as boiling point elevation, freezing point depression, vapor pressure lowering, and osmotic pressure. D) Reduced boiling points of pure liquids at increased altitudes is not a result of a solution's colligative properties but rather due to the decreased atmospheric pressure at higher altitudes.

Question 16

Sodium hydroxide is available commercially as a 50.0% by weight aqueous solution.Calculate the molality of this sodium hydroxide solution.
A)0.450 m
B)19.1 m
C)25.0 m
D)125.m

Accepted Answer

The answer of Sodium hydroxide is available commercially as a...

Question 17

At a given temperature the vapor pressures of benzene and toluene are 183 mm Hg and 59.2 mm Hg,respectively.Calculate the total vapor pressure over a solution of benzene and toluene with X_benzene = 0.400. A)110 mm Hg B)133 mm Hg C)109 mm Hg D)242 mm Hg

Accepted Answer

The answer of At a given temperature the vapor pressures...

Question 18

A 2.00 M solution of CaCl₂ in water has a density of 1.17 g/mL.What is the mole fraction of CaCl₂? A)0.0348 B)0.0360 C)0.0366 D)0.0380

Accepted Answer

The mole fraction of a solute in a solution can be calculated using the formula: mole fraction = moles of solute / (moles of solute + moles of solvent). First, calculate the moles of CaCl2 in 1 L of solution: 2.00 mol. Then, find the mass of 1 L of solution: 1.17 g/mL * 1000 mL = 1170 g. Subtract the mass of CaCl2 (2.00 mol * 110.98 g/mol = 221.96 g) from the total mass to find the mass of water: 1170 g - 221.96 g = 948.04 g. Convert the mass of water to moles (948.04 g / 18.015 g/mol = 52.63 mol). Finally, calculate the mole fraction: 2.00 / (2.00 + 52.63) = 0.0366.

Question 19

A KCl solution is prepared by dissolving 60.0 g KCl in 250.0 g of water at 25°C.What is the vapor pressure of the solution if the vapor pressure of water at 25°C is 23.76 mm Hg?
A)20.5 mm Hg
B)21.3 mm Hg
C)22.5 mm Hg
D)25.5 mm Hg

Accepted Answer

The vapor pressure of a solution is given by Raoult's law, which is expressed as P = X_water P_water, where P is the vapor pressure of the solution, X_water is the mole fraction of water, and P_water is the vapor pressure of pure water. To calculate the mole fraction of water, we need to know the moles of KCl and water in the solution.

Moles of KCl = 60.0 g / 74.55 g/mol = 0.804 mol
Moles of water = 250.0 g / 18.015 g/mol = 13.874 mol

Total moles of solute and solvent = 0.804 mol + 13.874 mol = 14.678 mol

Mole fraction of water = 13.874 mol / 14.678 mol = 0.944

Substituting the values in Raoult's law, we get:
P = 0.944 x 23.76 mm Hg = 22.44 mm Hg, which is approximately 21.3 mm Hg.

Therefore, the correct answer is B) 21.3 mm Hg.

Question 20

The Henry's Law constant of methyl bromide,CH₃Br,is k = 0.159 mol/(L ∙ atm)at 25°C.What is the solubility of methyl bromide in water at 25°C and at a partial pressure of 250.mm Hg? A)0.0523 mol/L B)0.329 mol/L C)0.483 mol/L D)39.8 mol/L

Accepted Answer

Henry's Law states that the solubility of a gas in a liquid is directly proportional to the pressure of that gas above the liquid. The formula for Henry's Law is S = kP, where S is the solubility of the gas (in mol/L), k is the Henry's Law constant (in mol/(L·atm)), and P is the partial pressure of the gas (in atm). Given that the Henry's Law constant, k, for methyl bromide is 0.159 mol/(L·atm) and the partial pressure is 250 mm Hg, which is equivalent to 250 mm Hg * (1 atm / 760 mm Hg) = 0.3289 atm, the solubility, S, can be calculated as follows: S = 0.159 mol/(L·atm) * 0.3289 atm = 0.0523 mol/L.

Quiz 12: Solutions and Their Properties

Sodium hydroxide is available commercially as a 50.0% by weight aqueous solution.The density of the solution is 1.53 g/mL.Calculate the molarity of this sodium hydroxide solution.

Which of the following statements is true for a supersaturated solution?

A solution of LiCl in water has X_LiCl = 0.0400.What is the molality?

The solubility of argon in water at 25°C is 0.0150 mol/L.What is the Henry's Law constant for argon if the partial pressure of argon in air is 0.00934 atm?

The solubility of gaseous solutes in liquid solvents is greater when the

At a given temperature the vapor pressures of benzene and toluene are 183 mm Hg and 59.2 mm Hg,respectively.Calculate the mole fraction of benzene in the vapor phase over a solution of benzene and toluene with X_benzene = 0.600.

Aqueous solutions of 30.0% (by weight) hydrogen peroxide,H₂O₂,are used to oxidize metals or organic molecules in chemical reactions.Calculate the molality of this solution.

At 25.0°C,a solution has a concentration of 3.179 M and a density of 1.260 g/mL.The density of the solution at 50.0°C is 1.249 g/mL.What is the molarity of the solution at 50.0°C?

In general,as the temperature increases,the solubility of gases in water and the solubility of most solids in water .

Which of the following aqueous salt (NaCl) solutions has the greater concentration?

A 3.17 m solution of CaCl₂ in water has a density of 1.24 g/mL.What is the molarity?

Aqueous solutions of 30% (by weight) hydrogen peroxide,H₂O₂,are used to oxidize metals or organic molecules in chemical reactions.Given that the density of the solution is 1.11 g/mL,calculate the molarity.

A solution is prepared by dissolving 20.0 g of sucrose,C₁₂H₂₂O₁₁,in 250.g of water at 25°C.What is the vapor pressure of the solution if the vapor pressure of water at 25°C is 23.76 mm Hg?

A solution of LiCl in water is 9.00 wt% LiCl.What is the mole fraction of LiCl?

Which of the following is not an application of colligative properties?

Sodium hydroxide is available commercially as a 50.0% by weight aqueous solution.Calculate the molality of this sodium hydroxide solution.

At a given temperature the vapor pressures of benzene and toluene are 183 mm Hg and 59.2 mm Hg,respectively.Calculate the total vapor pressure over a solution of benzene and toluene with X_benzene = 0.400.

A 2.00 M solution of CaCl₂ in water has a density of 1.17 g/mL.What is the mole fraction of CaCl₂?

A KCl solution is prepared by dissolving 60.0 g KCl in 250.0 g of water at 25°C.What is the vapor pressure of the solution if the vapor pressure of water at 25°C is 23.76 mm Hg?

The Henry's Law constant of methyl bromide,CH₃Br,is k = 0.159 mol/(L ∙ atm) at 25°C.What is the solubility of methyl bromide in water at 25°C and at a partial pressure of 250.mm Hg?

Quiz 12: Solutions and Their Properties

Sodium hydroxide is available commercially as a 50.0% by weight aqueous solution.The density of the solution is 1.53 g/mL.Calculate the molarity of this sodium hydroxide solution.

Which of the following statements is true for a supersaturated solution?

A solution of LiCl in water has XLiCl = 0.0400.What is the molality?

The solubility of argon in water at 25°C is 0.0150 mol/L.What is the Henry's Law constant for argon if the partial pressure of argon in air is 0.00934 atm?

The solubility of gaseous solutes in liquid solvents is greater when the

At a given temperature the vapor pressures of benzene and toluene are 183 mm Hg and 59.2 mm Hg,respectively.Calculate the mole fraction of benzene in the vapor phase over a solution of benzene and toluene with Xbenzene = 0.600.

Aqueous solutions of 30.0% (by weight) hydrogen peroxide,H2O2,are used to oxidize metals or organic molecules in chemical reactions.Calculate the molality of this solution.

At 25.0°C,a solution has a concentration of 3.179 M and a density of 1.260 g/mL.The density of the solution at 50.0°C is 1.249 g/mL.What is the molarity of the solution at 50.0°C?

In general,as the temperature increases,the solubility of gases in water ________ and the solubility of most solids in water ________.