Grade 12 : Chemistry - Solutions (Set 5)

Question 1

A solution is prepared by dissolving 29.25 g of NaCl (Molar mass = 58.5 g/mol) in enough water to make 500 mL of solution. What is the molarity of the solution?

Accepted Answer

B) 1.0 M

Answer

A) 0.5 M

Answer

C) 2.0 M

Answer

D) 0.25 M

Answer

E) 1.5 M

Question 2

Calculate the molality of a solution containing 18 g of glucose ($C_6H_{12}O_6$, Molar mass = 180 g/mol) dissolved in 200 g of water.

Accepted Answer

B) 0.50 m

Answer

A) 0.25 m

Answer

C) 0.75 m

Answer

D) 1.00 m

Answer

E) 0.10 m

Question 3

A solution contains 23 g of ethanol ($C_2H_5OH$, Molar mass = 46 g/mol) and 81 g of water ($H_2O$, Molar mass = 18 g/mol). What is the mole fraction of ethanol in the solution?

Accepted Answer

A) 0.1

Answer

B) 0.2

Answer

C) 0.3

Answer

D) 0.4

Answer

E) 0.5

Question 4

Substance	Molar Mass (g/mol)
Non-volatile solute (Y)	100
Solvent (Water)	18

The vapor pressure of pure water at 25°C is 23.8 mmHg. If 10 g of a non-volatile solute (Y) is dissolved in 180 g of water, what is the vapor pressure of the solution at 25°C?

Accepted Answer

D) 23.6 mmHg

Answer

A) 23.0 mmHg

Answer

B) 23.2 mmHg

Answer

C) 23.4 mmHg

Answer

E) 23.8 mmHg

Question 5

A solution contains 15 g of urea ($CO(NH_2)_2$, Molar mass = 60 g/mol) dissolved in 500 g of water. Given that the molal boiling point elevation constant ($K_b$) for water is 0.52 °C kg/mol, what is the boiling point of the solution? (Assume normal boiling point of water is 100°C).

Accepted Answer

B) 100.26 °C

Answer

A) 100.52 °C

Answer

C) 100.13 °C

Answer

D) 99.87 °C

Answer

E) 100.00 °C

Question 6

Calculate the freezing point of a solution prepared by dissolving 3.42 g of sucrose ($C_{12}H_{22}O_{11}$, Molar mass = 342 g/mol) in 100 g of water. The molal freezing point depression constant ($K_f$) for water is 1.86 °C kg/mol.

Accepted Answer

A) -0.186 °C

Answer

B) -0.372 °C

Answer

C) 0 °C

Answer

D) -1.86 °C

Answer

E) -0.093 °C

Question 7

What is the osmotic pressure (in atm) of a solution containing 10 g of glucose ($C_6H_{12}O_6$, Molar mass = 180 g/mol) in 500 mL of solution at 27°C? (R = 0.0821 L atm mol$^{-1}$ K$^{-1}$)

Accepted Answer

B) 2.72 atm

Answer

A) 1.36 atm

Answer

C) 0.68 atm

Answer

D) 5.44 atm

Answer

E) 1.00 atm

Question 8

A student is provided with a solubility curve for compound A in water, which shows that as temperature increases from 20°C to 80°C, the solubility of A increases from 30 g/100g water to 90 g/100g water, linearly. At 50°C, the solubility is 60 g/100g water.

Based on this information, which statement about compound A's solubility is correct?

Accepted Answer

E) Cooling a saturated solution of A from 80°C to 20°C would cause 60 g of A to precipitate from 100 g of water.

Answer

A) Compound A is likely a gas.

Answer

B) Solubility of A decreases by 1 g per degree Celsius increase.

Answer

C) At 50°C, 100 g of A can dissolve in 100 g of water to form a saturated solution.

Answer

D) Increasing pressure would significantly increase its solubility.

Question 9

A 0.1 M solution of $MgCl_2$ is prepared. Assuming complete dissociation, what would be the expected osmotic pressure of this solution at 27°C compared to a 0.1 M glucose solution at the same temperature? (R = 0.0821 L atm mol$^{-1}$ K$^{-1}$)

Accepted Answer

D) Three times that of glucose solution.

Answer

A) Same as glucose solution.

Answer

B) Half of glucose solution.

Answer

C) Twice that of glucose solution.

Answer

E) One-third of glucose solution.

Question 10

A 250 mL solution of 0.8 M HCl is diluted by adding water until its final volume is 1.0 L. What is the new molarity of the HCl solution?

Accepted Answer

A) 0.2 M

Answer

B) 0.4 M

Answer

C) 0.8 M

Answer

D) 0.1 M

Answer

E) 1.6 M

Question 11

The Henry's Law constant for oxygen dissolved in water at 25°C is $1.3 imes 10^{-3} ext{ mol L}^{-1} ext{ atm}^{-1}$. If the partial pressure of oxygen in the air above a water body is 0.21 atm, what is the concentration of dissolved oxygen in the water?

Accepted Answer

A) $2.73 	imes 10^{-4} m$

Answer

B) $1.3 	imes 10^{-3} m$

Answer

C) $6.19 	imes 10^{-3} m$

Answer

D) $2.73 	imes 10^{-3} m$

Answer

E) $1.3 	imes 10^{-4} m$

Question 12

Which of the following statements is true regarding a solution that shows positive deviation from Raoult's Law?

Accepted Answer

D) The solution forms a minimum boiling azeotrope.

Answer

A) The vapor pressure of the solution is lower than predicted by Raoult's Law.

Answer

B) The forces of attraction between solute-solvent molecules are stronger than solute-solute and solvent-solvent forces.

Answer

C) The enthalpy of mixing ($\Delta H_{mix}$) for such a solution is negative.

Answer

E) The solution forms a maximum boiling azeotrope.