Q: Which of the following is a correct conversion factor for a 12% (v/v) ethanol solution?

$$\frac{12\ \text{mL ethanol}}{100\ \text{mL solution}}$$

Q: Which of the following is a correct conversion factor for a 10% (m/m) KCl solution?

$$\frac{10\ \text{g KCl}}{100\ \text{g solution}}$$

Q: Which of the following is a correct conversion factor for a 5% (m/v) glucose solution?

$$\frac{5\ \text{g glucose}}{100\ \text{mL solution}}$$

Question 1

A solution is prepared by dissolving 15.0 g of Na2CO3 in 235 g of H2O. What is the mass percent (m/m) of Na2CO3 in the solution?

$$	ext{Mass percent (m/m)} = \frac{	ext{mass of solute (g)}}{	ext{mass of solute (g)} + 	ext{mass of solvent (g)}} 	imes 100\%$$

Accepted Answer

5.99%

Question 2

Which of the following best describes a 5% (m/v) glucose solution?

Accepted Answer

5 g of glucose in 100 mL of solution

Question 3

How many grams of NaOH are needed to prepare 75.0 g of a 14.0% (m/m) NaOH solution?

$$	ext{Mass percent (m/m)} = \frac{	ext{mass of solute}}{	ext{mass of solution}} 	imes 100\%$$

Accepted Answer

10.5 g

Question 4

What is the molarity of a solution prepared by dissolving 34.8 g of KNO3 in enough water to make 0.225 L of solution? (Molar mass of KNO3 = 101.1 g/mol)

$$	ext{Molarity (M)} = \frac{	ext{moles of solute}}{	ext{liters of solution}}$$

Accepted Answer

1.54 M

Question 5

Which of the following is a correct conversion factor for a 12% (v/v) ethanol solution?

Accepted Answer

$$\frac{12\ 	ext{mL ethanol}}{100\ 	ext{mL solution}}$$

Question 6

A nurse needs to prepare 100 mL of a 4.8% (m/v) HCl solution. How many grams of HCl are required?

$$	ext{Mass/volume percent (m/v)} = \frac{	ext{mass of solute (g)}}{	ext{volume of solution (mL)}} 	imes 100\%$$

Accepted Answer

4.8 g

Question 7

Which of the following statements about molarity is correct?

Accepted Answer

Molarity is the number of moles of solute per liter of solution.

Question 8

A laboratory technician has 2.25 mL of ethanol and wants to prepare a 5.75% (v/v) ethanol solution. What is the final volume of solution that can be prepared?

$$	ext{Volume percent (v/v)} = \frac{	ext{volume of solute}}{	ext{volume of solution}} 	imes 100\%$$

Accepted Answer

39.1 mL

Question 9

Which of the following is NOT a correct way to express solution concentration?

Accepted Answer

Grams of solute per 100 mL of solvent

Question 10

A 1.0 M NaCl solution contains:

Accepted Answer

1.0 mole of NaCl in 1 L of solution

Question 11

A solution is made by adding 8.00 g of KCl to enough water to make 50.00 g of solution. What is the mass percent (m/m) of KCl?

$$	ext{Mass percent (m/m)} = \frac{8.00}{50.00} 	imes 100\%$$

Accepted Answer

16.0%

Question 12

Which of the following is a correct conversion factor for a 10% (m/m) KCl solution?

Accepted Answer

$$\frac{10\ 	ext{g KCl}}{100\ 	ext{g solution}}$$

Question 13

A chemist needs to prepare 250 mL of a 2.0% (m/v) NaCl solution. How many grams of NaCl are required?

$$	ext{Mass/volume percent (m/v)} = \frac{	ext{mass of solute (g)}}{	ext{volume of solution (mL)}} 	imes 100\%$$

Accepted Answer

5.0 g

Question 14

Which of the following best describes the difference between mass percent (m/m) and mass/volume percent (m/v)?

Accepted Answer

Mass percent uses grams of solute per 100 g of solution, while mass/volume percent uses grams of solute per 100 mL of solution.

Question 15

A 6.0 M HCl solution contains:

Accepted Answer

6.0 moles of HCl in 1 L of solution

Question 16

Which of the following is a correct conversion factor for a 5% (m/v) glucose solution?

Accepted Answer

$$\frac{5\ 	ext{g glucose}}{100\ 	ext{mL solution}}$$

Calculating Solution Concentration in GOB Chemistry

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