Question 1

Most volatile liquids can be separated from each other by fractional distillation.

Accepted Answer

Fractional distillation is a process of separating components of a mixture based on their boiling points. As different liquids have different boiling points, they can be separated from each other by fractional distillation. The more volatile liquids will have lower boiling points and will evaporate first, while the less volatile liquids will have higher boiling points and will remain in the distillation column.

Question 2

Which compound is most likely to be soluble in water? A) butyl alcohol (CH₃CH₂CH₂CH₂OH) B) ethylene glycol (HOCH₂CH₂OH) C) hexane (C₆H₁₄) D) benzene (C₆H₁₂) E) iodine (I₂)

Accepted Answer

Ethylene glycol is highly soluble in water due to its two hydroxyl (OH) groups, which can form hydrogen bonds with water molecules.

Question 3

Liquid Q is a polar solvent and liquid R is a nonpolar solvent. On the basis of this information, you would expect: A) both liquids to be miscible with a third liquid T B) liquid Q to be miscible with liquid R C) NaCl to be soluble to both Q and R D) liquid Q and H₂O to be miscible E) liquid R and H₂O to be miscible

Accepted Answer

Polar solvents like liquid Q and water (H₂O) are generally miscible with each other due to their ability to form hydrogen bonds and other polar interactions.

Question 4

A magnesium sulfate heptahydrate solution, which is 18.00% by weight in the anhydrous compound, has a density at 20°C of 1.20 g/mL. What is the molality of the anhydrous compound in the solution? (Atomic weights: H = 1.0, O = 16.0, S = 32.1, Mg = 24.3)
A) 5.54 M
B) 1.79 M
C) 1.82 M
D) 1.25 M
E) 1.49 M

Accepted Answer

First, we need to calculate the molar mass of MgSO4•7H2O:
Mg = 24.3 g/mol
S = 32.1 g/mol
O (4 x 16.0 g/mol) = 64.0 g/mol
H2O (7 x 18.0 g/mol) = 126.0 g/mol
Total molar mass = 246.4 g/mol

Next, we need to calculate the mass of MgSO4 in 100 g (or 100 mL) of solution:
18.00 g MgSO4•7H2O / 100 g solution = x g MgSO4 / 100 g solution
x = 18.00 g MgSO4

Using the density of the solution, we can calculate the volume of 100 g (or 100 mL) of solution:
100 g solution / 1.20 g/mL = 83.3 mL

Next, we convert the mass of MgSO4 to moles:
18.00 g MgSO4 x (1 mol / 246.4 g) = 0.07310 mol MgSO4

Finally, we can calculate the molality of the solution:
molality = moles of solute / mass of solvent (in kg)
mass of solvent = volume x density = 83.3 mL x 1.20 g/mL = 99.96 g = 0.09996 kg

molality = 0.07310 mol / 0.09996 kg = 0.7318 mol/kg = 0.7318 M

However, the question asks for the molality of the anhydrous compound, which has a molar mass of 120.4 g/mol. If we assume that all of the MgSO4•7H2O dissolves and dissociates in water, we can calculate the molality of the anhydrous compound:
moles of MgSO4 = 0.07310 mol MgSO4•7H2O x (1 mol MgSO4 / 1 mol MgSO4•7H2O) = 0.07310 mol MgSO4
mass of MgSO4 = 0.07310 mol MgSO4 x 120.4 g/mol = 8.805 g MgSO4
mass of solvent = 99.96 g - 18.00 g (mass of MgSO4•7H2O) = 81.96 g = 0.08196 kg

molality = 0.07310 mol / 0.08196 kg = 0.8908 mol/kg = 0.8908 M

However, we need to convert this to molality of the anhydrous compound only, which means we need to account for the fact that MgSO4•7H2O has a mass of 246.4 g/mol, while MgSO4 has a mass of 120.4 g/mol:
moles of MgSO4 = 0.07310 mol MgSO4•7H2O = 0.07310 mol x (120.4 g/mol / 246.4 g/mol) = 0.03552 mol MgSO4
mass of solvent = 81.96 g
molality = 0.03552 mol / 0.08196 kg = 0.4334 mol/kg = 0.4334 M

Finally, we need to convert this to molality of the anhydrous compound in percentage:
molality = 0.4334 M x (120.4 g/mol / 246.4 g/mol) = 0.2113 M = 21.13%

Therefore, the molality of the anhydrous compound in the solution is 1.82 M (rounded to two significant figures).

Question 5

The van't Hoff factor is due to ions being attracted to each other enough that they don't react as individual molecules.

Accepted Answer

The van't Hoff factor is related to the degree of dissociation of a solute in solution, indicating how many particles a solute forms in solution, not the attraction between ions.

Question 6

Osmotic pressure is a colligative property.

Accepted Answer

Osmotic pressure depends on the concentration of solute particles in a solution, and this concentration is a colligative property that depends only on the number of particles present, not on their identity. Therefore, osmotic pressure is a colligative property.

Question 7

Molality is independent of temperature, molarity is dependent on temperature.

Accepted Answer

Molality is based on mass of solvent, which does not change with temperature, whereas molarity is based on volume of solution, which can change with temperature due to thermal expansion.

Question 8

In the solution, a solute is present in the greatest quantity.

Accepted Answer

A solution is a homogeneous mixture consisting of a solute (the substance being dissolved) and a solvent (the substance doing the dissolving). The amount of solute present in a solution can vary and is not necessarily in the greatest quantity. In fact, often the opposite is true, where the solvent is present in the greater amount.

Question 9

A solid solution of zinc in copper is an example of:
A) a solvent
B) a solute
C) the U.S. five-cent nickel
D) a non-uniform solute
E) an alloy

Accepted Answer

A solid solution of zinc in copper is an example of an alloy. An alloy is a mixture of two or more metals, with at least one of them being a metal. In this case, copper is the solvent, and zinc is the solute, creating an alloy. The U.S. five-cent nickel is also an alloy, but it contains copper, nickel, and trace amounts of other elements, whereas the question specifically refers to a solid solution of zinc in copper.

Question 10

An unsaturated solution will have some solid undissolved in the bottom of the container.

Accepted Answer

An unsaturated solution means that the solvent has not yet dissolved as much solute as it can at a given temperature and pressure. Therefore, there should be no solid undissolved in the bottom of the container.

Question 11

A solution prepared by dissolving 4.00 g KCl in 36.0 g H₂O is said to be: A) 11.1% KCl by mass B) 0.100% KCl by mass C) 0.111% KCl by mass D) 10.0% KCl by mass E) 9.00% KCl by mass

Accepted Answer

The answer of A solution prepared by dissolving 4.00 g...

Question 12

A sweetened cup of coffee is an example of a:
A) heterogeneous mixture
B) homogeneous mixture
C) solid solution
D) pure liquid
E) gaseous solute in a liquid solvent

Accepted Answer

A sweetened cup of coffee is a homogeneous mixture because the sugar and coffee are evenly distributed throughout the liquid, meaning it has the same composition and properties throughout.

Question 13

Which definition is INCORRECT?
A) mole fraction = moles of solute/moles of solution
B) molality = moles of solute/kilogram of solvent
C) weight percent = grams of solute/100 grams of solution
D) molarity = moles of solute/liter of solution
E) volume percent=volume of solute/volume of solution

Accepted Answer

The answer of Which definition is INCORRECT?
A) mole fraction =...

Question 14

Adding a solute to a solvent lowers the freezing point of the solution compared to the pure solvent.

Accepted Answer

This is known as the phenomenon of freezing point depression, where adding a solute to a solvent disrupts the orderly arrangement of solvent molecules in the liquid state, making it more difficult for them to form a solid lattice and therefore lowering the freezing point of the solution.

Question 15

A 1.00 molal solution of NaCl in water contains: A) 1.00 g NaCl per 1000.0 g H₂O B) 1.00 mol NaCl per 1000.0 g H₂O C) 1.00 mol NaCl per 1000.0 kg H₂O D) 1000.0 g NaCl per 1000.0 g H₂O E) 1.00 mol NaCl per 1000.0 mol H₂O

Accepted Answer

The answer of A 1.00 molal solution of NaCl in...

Question 16

For the formation of an ideal solution from two liquid hydrocarbons, ΔHsoln < 0.

Accepted Answer

In an ideal solution, the enthalpy of mixing (ΔHsoln) is zero because the interactions between different molecules are similar to those between like molecules.

Question 17

Gas solubility always increases with temperature.

Accepted Answer

Gas solubility decreases with increasing temperature because as temperature increases, the kinetic energy of the solvent molecules increases which makes it difficult for the gas molecules to remain dissolved in the solvent.

Question 18

Which of the following pairs are more likely to form a solution? A) chloroform (CHCl₃) and acetone (CH₃COCH₃) B) water and octane (C₈H₁₈) C) methanol (CH₃OH) and hexane (C₆H₁₄) D) water and octyl alcohol (C₈H₁₇OH) E) acetone (CH₃COCH₃) and octane (C₈H₁₃)

Accepted Answer

The answer of Which of the following pairs are more...

Question 19

An aqueous solution containing 1.0 g ephedrine in 20.0 mL solution is said to be:
A) 5.0% ephedrine (mass/vol)
B) 1.0% ephedrine (mass/vol)
C) 0.50% ephedrine (mass/vol)
D) 0.050% ephedrine (mass/vol)
E) 20.0% ephedrine (mass/vol)

Accepted Answer

The concentration of ephedrine in the solution is calculated as mass of solute (ephedrine) per volume of solution, expressed as a percentage. Here, it is $\frac{1.0\,g}{20.0\,mL} \times 100\% = 5.0\%$.

Question 20

The stronger the forces between solute and solvent molecules, the more exothermic the solution process.

Accepted Answer

The stronger the forces between solute and solvent molecules, the more energy is released when they come together, making the solution process more exothermic.

Quiz 13: Solutions and Their Physical Properties

Most volatile liquids can be separated from each other by fractional distillation.

Which compound is most likely to be soluble in water?

Liquid Q is a polar solvent and liquid R is a nonpolar solvent. On the basis of this information, you would expect:

A magnesium sulfate heptahydrate solution, which is 18.00% by weight in the anhydrous compound, has a density at 20°C of 1.20 g/mL. What is the molality of the anhydrous compound in the solution? (Atomic weights: H = 1.0, O = 16.0, S = 32.1, Mg = 24.3)

The van't Hoff factor is due to ions being attracted to each other enough that they don't react as individual molecules.

Osmotic pressure is a colligative property.

Molality is independent of temperature, molarity is dependent on temperature.

In the solution, a solute is present in the greatest quantity.

A solid solution of zinc in copper is an example of:

An unsaturated solution will have some solid undissolved in the bottom of the container.

A solution prepared by dissolving 4.00 g KCl in 36.0 g H2O is said to be:

A sweetened cup of coffee is an example of a:

Which definition is INCORRECT?

Adding a solute to a solvent lowers the freezing point of the solution compared to the pure solvent.

A 1.00 molal solution of NaCl in water contains:

For the formation of an ideal solution from two liquid hydrocarbons, ΔHsoln < 0.

Gas solubility always increases with temperature.

Which of the following pairs are more likely to form a solution?

An aqueous solution containing 1.0 g ephedrine in 20.0 mL solution is said to be:

The stronger the forces between solute and solvent molecules, the more exothermic the solution process.

A solution prepared by dissolving 4.00 g KCl in 36.0 g H₂O is said to be: