Q: A laboratory technician needs to prepare 500 mL of 0.10 M NaOH from a 2.0 M stock solution. What volume of stock solution should be used?

$$V_1$$ = \frac{0.10 \times 0.500}{2.0} = 0.025$$ L = 25 mL

Q: A student mixes 100 mL of 0.20 M lead(II) nitrate with 100 mL of 0.20 M potassium iodide. What mass of lead(II) iodide ($$PbI_2$$, $$M = 461 g/$$mol) will precipitate? Assume complete reaction.

0.020 mol $$PbI_2$$; mass = $$0.020 \times 461 = 9.22 g$$

Question 1

Which of the following statements best describes the role of water as a solvent in an aqueous solution?

Accepted Answer

Water is the solvent, providing the medium in which the solute dissolves.

Question 2

A solution is prepared by dissolving 5.00 g of NaCl in enough water to make 250 mL of solution. What is the molarity of the solution? ($$M_{NaCl}$$: 58.44 g/mol)

Accepted Answer

$$M = \frac{5.00 \div 58.44}{0.250} = 0.342 M$$

Question 3

Which of the following best explains why ionic compounds conduct electricity when dissolved in water?

Accepted Answer

Ionic compounds dissociate into ions, which move freely and carry charge.

Question 4

A laboratory technician needs to prepare 500 mL of 0.10 M NaOH from a 2.0 M stock solution. What volume of stock solution should be used?

Accepted Answer

$$V_1$$ = \frac{0.10 	imes 0.500}{2.0} = 0.025$$ L = 25 mL

Question 5

Which of the following is a correct net ionic equation for the precipitation reaction between aqueous solutions of silver nitrate and sodium chloride?

Accepted Answer

$$Ag^+(aq) + Cl^-(aq) \rightarrow AgCl(s)$$

Question 6

Which of the following pairs of solutions will produce a precipitate when mixed?

Accepted Answer

Barium chloride(aq) and sodium sulfate(aq)

Question 7

A student mixes 100 mL of 0.20 M lead(II) nitrate with 100 mL of 0.20 M potassium iodide. What mass of lead(II) iodide ($$PbI_2$$, $$M = 461 g/$$mol) will precipitate? Assume complete reaction.

Accepted Answer

0.020 mol $$PbI_2$$; mass = $$0.020 	imes 461 = 9.22 g$$

Question 8

Which of the following is a strong acid?

Accepted Answer

Hydrobromic acid ($$HBr)$$

Question 9

Which statement correctly describes the difference between strong and weak electrolytes?

Accepted Answer

Strong electrolytes dissociate completely into ions in solution.

Question 10

What is the net ionic equation for the reaction between hydrochloric acid and sodium hydroxide?

Accepted Answer

$$H^+(aq) + OH^-(aq) \rightarrow H_2O(l)$$

Question 11

A 25.0 mL sample of 0.200 M $$H_2SO_4 is $$titrated with 0.100 M NaOH. What volume of NaOH is required to reach the equivalence point?

Accepted Answer

50.0 mL

Question 12

Which of the following is the correct oxidation number for sulfur in $$SO_3$$?

Accepted Answer

+6

Question 13

In the reaction $$2Al(s) + 3H_2SO_4(aq) \rightarrow Al_2$(SO_4$)_3(aq) + 3H_2(g)$$, which species is oxidized?

Accepted Answer

$$Al$$

Question 14

Which of the following reactions is a decomposition reaction?

Accepted Answer

$$2H_2O_2(l) \rightarrow 2H_2O(l) + O_2$(g)$$

Question 15

A redox titration is performed using $$KMnO_4 to $$determine the amount of $$Ca^{2+} in $$blood. Which species acts as the oxidizing agent?

Accepted Answer

$$KMnO_4$$

Question 16

Which of the following best describes the equilibrium state in a chemical reaction?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 17

Which of the following is the correct molecular equation for the reaction between magnesium chloride and calcium hydroxide to precipitate magnesium hydroxide?

Accepted Answer

$$MgCl_2(aq) + Ca(OH)_2(aq$$) \rightarrow Mg(OH)_2(s) + $$CaCl_2(aq$$)$$

Question 18

Which of the following is a correct total ionic equation for the reaction between potassium fluoride and strontium nitrate?

Accepted Answer

$$2K^+(aq) + 2F^-(aq) + Sr$$^{2+}$$(aq) + 2NO_3^-(aq) \rightarrow $$SrF_2$$(s) + 2K^+(aq) + 2NO_3^-(aq)$$

Chapter 4: Three Major Classes of Chemical Reactions – Solution Concentration and the Role of Water as a Solvent

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