Q: What is the mass percent of ethanol ($\mathrm{C_2H_5OH}$) in a solution containing 8.72 g ethanol dissolved in 76.1 g water?

$\frac{8.72}{8.72 + 76.1} \times 100 = 10.3\%$

Q: A saline solution contains 2.45% NaCl by mass. How many grams of NaCl are present in 6.71 g of this solution?

$6.71 \times 0.0245 = 0.164\ \mathrm{g}$

Q: How many moles of NaI are present in 3.4 L of a 0.101 M NaI solution?

$3.4 \times 0.101 = 0.343\ \mathrm{mol}$

Q: A student takes 25.0 mL of a 5.5 M KBr solution and dilutes it to 100.0 mL. What is the molarity of the diluted solution?

$\frac{25.0 \times 5.5}{100.0} = 1.375\ \mathrm{M}$

Q: How would you prepare 500.0 mL of a 0.200 M NaOH solution from a 1.5 M NaOH stock solution?

Use $V_1 = \frac{0.200 \times 500.0}{1.5} = 66.7\ \mathrm{mL}$ of stock and dilute to 500.0 mL

Q: What is the freezing point depression ($\Delta T_f$) of water when 1.75 molal ($m$) solution is prepared, given $K_f = 1.86\ ^\circ\mathrm{C}\ \mathrm{kg\ solute}^{-1}$?

$\Delta T_f = m \times K_f = 1.75 \times 1.86 = 3.26\ ^\circ\mathrm{C}$

Question 1

Which of the following best describes the solute and solvent in a solution of 8.72 g ethanol ($\mathrm{C_2H_5OH}$) dissolved in 76.1 g water?

Accepted Answer

Solute: ethanol; Solvent: water

Question 2

Which of the following substances will most likely dissolve in a non-polar solvent such as hexane?

Accepted Answer

Lard (fat)

Question 3

Which of the following is NOT a common non-polar solvent?

Accepted Answer

Water

Question 4

What is the mass percent of ethanol ($\mathrm{C_2H_5OH}$) in a solution containing 8.72 g ethanol dissolved in 76.1 g water?

Accepted Answer

$\frac{8.72}{8.72 + 76.1} 	imes 100 = 10.3\%$

Question 5

A saline solution contains 2.45% NaCl by mass. How many grams of NaCl are present in 6.71 g of this solution?

Accepted Answer

$6.71 	imes 0.0245 = 0.164\ \mathrm{g}$

Question 6

A solution contains 12.0 g sucrose and has a concentration of 4.1 % (m/m). What is the total mass of the solution?

Accepted Answer

$\frac{12.0}{0.041} = 293\ \mathrm{g}$

Question 7

How many moles of NaI are present in 3.4 L of a 0.101 M NaI solution?

Accepted Answer

$3.4 	imes 0.101 = 0.343\ \mathrm{mol}$

Question 8

What is the volume in liters of a solution that contains 0.325 moles of NaI and has a concentration of 0.982 M?

Accepted Answer

$\frac{0.325}{0.982} = 0.331\ \mathrm{L}$

Question 9

A student takes 25.0 mL of a 5.5 M KBr solution and dilutes it to 100.0 mL. What is the molarity of the diluted solution?

Accepted Answer

$\frac{25.0 	imes 5.5}{100.0} = 1.375\ \mathrm{M}$

Question 10

How would you prepare 500.0 mL of a 0.200 M NaOH solution from a 1.5 M NaOH stock solution?

Accepted Answer

Use $V_1 = \frac{0.200 	imes 500.0}{1.5} = 66.7\ \mathrm{mL}$ of stock and dilute to 500.0 mL

Question 11

What is the freezing point depression ($\Delta T_f$) of water when 1.75 molal ($m$) solution is prepared, given $K_f = 1.86\ ^\circ\mathrm{C}\ \mathrm{kg\ solute}^{-1}$?

Accepted Answer

$\Delta T_f = m 	imes K_f = 1.75 	imes 1.86 = 3.26\ ^\circ\mathrm{C}$

Question 12

Which of the following is NOT a property of acids?

Accepted Answer

Feel slippery

Question 13

Which of the following is a Bronsted-Lowry base in the reaction $\mathrm{NH_3} + \mathrm{H_2O} \rightarrow \mathrm{NH_4^+} + \mathrm{OH^-}$?

Accepted Answer

$\mathrm{NH_3}$

Question 14

Which of the following is the conjugate base of $\mathrm{HCO_3^-}$?

Accepted Answer

$\mathrm{CO_3^{2-}}$

Question 15

Classify the following acid as strong or weak: $\mathrm{HNO_3}$

Accepted Answer

Strong acid

Question 16

Classify the following base as strong or weak: $\mathrm{NH_3}$

Accepted Answer

Weak base

Question 17

In the reaction $\mathrm{HClO_4} + \mathrm{H_2O} \rightarrow \mathrm{H_3O^+} + \mathrm{ClO_4^-}$, which species is the conjugate base?

Accepted Answer

$\mathrm{ClO_4^-}$

Question 18

Which of the following is a property of bases?

Accepted Answer

Feel slippery

Solutions, Acids, and Bases: Key Concepts and Calculations

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