Q: Which of the following is the correct formula for calculating molarity?

$\mathrm{M} = \frac{\text{moles of solute}}{\text{liters of solution}}$

Question 1

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

$\mathrm{CH}_2\mathrm{O}$

Question 2

A compound has an empirical formula of $\mathrm{CH}_2\mathrm{O}$ and a molar mass of 180 g/mol. What is its molecular formula?

Accepted Answer

$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6$

Question 3

A hydrate of magnesium sulfate has a mass of 5.00 g before heating and 2.44 g after heating. What is the empirical formula of the hydrate?

Accepted Answer

$\mathrm{MgSO}_4 \cdot 2\mathrm{H}_2\mathrm{O}$

Question 4

What is the percent composition by mass of nitrogen in ammonium nitrate ($\mathrm{NH}_4\mathrm{NO}_3$)?

Accepted Answer

35.0%

Question 5

How many moles of sodium ions are present in 250 mL of 0.20 M $\mathrm{Na}_2\mathrm{SO}_4$ solution?

Accepted Answer

0.10 mol

Question 6

A solution is prepared by dissolving 0.50 g of $\mathrm{KMnO}_4$ in enough water to make 250 mL of solution. What is the molarity of the solution? ($\mathrm{M_{KMnO_4}} = 158.04$ g/mol)

Accepted Answer

$0.013$ M

Question 7

If 25.0 mL of 0.100 M $\mathrm{HCl}$ is diluted to a final volume of 100.0 mL, what is the final concentration?

Accepted Answer

$0.025$ M

Question 8

Which of the following solutions will have the highest boiling point elevation?

Accepted Answer

0.10 M $\mathrm{CaCl}_2$

Question 9

A student uses Beer’s Law to determine the concentration of a solution. If the absorbance is 0.400 and the molar absorptivity is $2.00 	imes 10^3$ L/(mol·cm) with a path length of 1.00 cm, what is the concentration?

Accepted Answer

$2.00 	imes 10^{-4}$ M

Question 10

Which of the following is a strong electrolyte?

Accepted Answer

$\mathrm{NaCl}$

Question 11

Which of the following statements best describes a saturated solution?

Accepted Answer

A solution that contains the maximum amount of solute that can dissolve at a given temperature.

Question 12

What is the pH of a 0.0010 M $\mathrm{HCl}$ solution?

Accepted Answer

3.0

Question 13

Which of the following is NOT a colligative property?

Accepted Answer

Density

Question 14

A solution is made by dissolving 10.0 g of $\mathrm{NaCl}$ in 500.0 g of water. What is the mass percent of $\mathrm{NaCl}$ in the solution?

Accepted Answer

2.0%

Question 15

Which of the following best describes the process of dissociation?

Accepted Answer

The separation of ions when an ionic compound dissolves in water.

Question 16

Which of the following acids is considered strong?

Accepted Answer

$\mathrm{HNO_3}$

Question 17

A solution contains 0.20 mol of $\mathrm{KCl}$ in 1.0 L of water. What is the molarity of chloride ions?

Accepted Answer

0.20 M

Question 18

Which of the following is the correct formula for calculating molarity?

Accepted Answer

$\mathrm{M} = \frac{	ext{moles of solute}}{	ext{liters of solution}}$

Question 19

A solution of $\mathrm{NaOH}$ has a pH of 13. What is the concentration of $\mathrm{OH^-}$ ions?

Accepted Answer

$1 	imes 10^{-1}$ M

General Chemistry Unit 2: Key Concepts and Calculations

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