Q: A student prepares a solution by dissolving 25.5 g of KBr in enough water to make 1.75 L of solution. What is the molarity of the solution? (Molar mass of KBr = 119.00 g/mol)

$$M = \frac{25.5}{119.00 \times 1.75} = 0.122\ \mathrm{M}$$

Q: What is the correct formula for calculating molarity?

$$M = \frac{\text{amount of solute (in mol)}}{\text{volume of solution (in L)}}$$

Q: A chemist wants to prepare 3.00 L of 0.500 M CaCl$$_2$$ solution from a 10.0 M stock solution. What volume of the stock solution should be used?

$$V_1$$ = \frac{$$M_2$$ $$V_2$$}{$$M_1$$} = \frac{0.500 \times 3.00}{10.0} = 0.150\ \mathrm{L}$$

Q: A student mixes 20.0 mL of 0.50 M NaCl solution. How many moles of NaCl are present?

$$0.0200\ \mathrm{L} \times 0.50\ \mathrm{mol/L} = 0.010\ \mathrm{mol}$$

Question 1

Which of the following statements best describes a solution?

Accepted Answer

A homogeneous mixture in which the solute is evenly distributed within the solvent.

Question 2

A student prepares a solution by dissolving 25.5 g of KBr in enough water to make 1.75 L of solution. What is the molarity of the solution? (Molar mass of KBr = 119.00 g/mol)

Accepted Answer

$$M = \frac{25.5}{119.00 	imes 1.75} = 0.122\ \mathrm{M}$$

Question 3

Which of the following best describes the difference between a dilute and a concentrated solution?

Accepted Answer

A dilute solution has more solvent and less solute, while a concentrated solution has more solute and less solvent.

Question 4

What is the correct formula for calculating molarity?

Accepted Answer

$$M = \frac{	ext{amount of solute (in mol)}}{	ext{volume of solution (in L)}}$$

Question 5

A chemist wants to prepare 3.00 L of 0.500 M CaCl$$_2$$ solution from a 10.0 M stock solution. What volume of the stock solution should be used?

Accepted Answer

$$V_1$$ = \frac{$$M_2$$ $$V_2$$}{$$M_1$$} = \frac{0.500 	imes 3.00}{10.0} = 0.150\ \mathrm{L}$$

Question 6

Which of the following is true about the process of dilution?

Accepted Answer

The amount of solute remains constant, but the volume of solution increases.

Question 7

A solution contains 0.255 mol NaOH in 2.04 L of solution. What is the molarity of NaOH?

Accepted Answer

$$M = \frac{0.255}{2.04} = 0.125\ \mathrm{M}$$

Question 8

Which of the following best explains why NaCl conducts electricity when dissolved in water, but sugar does not?

Accepted Answer

NaCl forms ions in solution, while sugar remains as intact molecules.

Question 9

Which of the following is a strong electrolyte?

Accepted Answer

NaCl (sodium chloride)

Question 10

A student mixes 20.0 mL of 0.50 M NaCl solution. How many moles of NaCl are present?

Accepted Answer

$$0.0200\ \mathrm{L} 	imes 0.50\ \mathrm{mol/L} = 0.010\ \mathrm{mol}$$

Question 11

Which of the following statements about electrolytes is correct?

Accepted Answer

Nonelectrolytes do not form ions when dissolved in water.

Question 12

Which of the following is the correct net ionic equation for the reaction between K$$_2SO$_4(aq) $$and AgNO$$_3(aq) to $$form Ag$$_2SO$_4(s$$)?

Accepted Answer

$$2\mathrm{Ag}^+(aq) + \mathrm{SO}_4$$^{2-}$$(aq) \rightarrow \mathrm{Ag}_2\mathrm{SO}_4(s)$$

Question 13

Which of the following is a correct molecular equation for the precipitation reaction between Pb(NO$$_3$$)$$_2(aq) $$and KI(aq)?

Accepted Answer

$$2\mathrm{KI}(aq) + \mathrm{Pb(NO}_3)_2(aq) \rightarrow 2\mathrm{KNO}_3(aq) + \mathrm{PbI}_2(s)$$

Question 14

Which of the following best describes the role of spectator ions in a chemical reaction?

Accepted Answer

They remain unchanged and do not participate in the reaction.

Question 15

Which of the following is the correct net ionic equation for the neutralization of HCl(aq) with NaOH(aq)?

Accepted Answer

$$\mathrm{H}^+(aq) + \mathrm{OH}^-(aq) \rightarrow \mathrm{H}_2\mathrm{O}(l)$$

Question 16

A student is performing an acid-base titration using 0.100 M NaOH to neutralize 25.0 mL of HCl. If it takes 30.0 mL of NaOH to reach the endpoint, what is the concentration of HCl?

Accepted Answer

$$M_{HCl} = \frac{M_{NaOH} 	imes V_{NaOH}}{V_{HCl}} = \frac{0.100 	imes 0.0300}{0.0250} = 0.120\ \mathrm{M}$$

Question 17

Which of the following reactions is a gas-evolution reaction?

Accepted Answer

$$\mathrm{NaHCO}_3(aq) + \mathrm{HCl}(aq) \rightarrow \mathrm{NaCl}(aq) + \mathrm{H}_2\mathrm{O}(l) + \mathrm{CO}_2(g)$$

Question 18

Which of the following is the correct oxidation state of nitrogen in NO$$_3^-$$?

Accepted Answer

$$+5$$

Question 19

In the reaction $$2\mathrm{Na}(s) + \mathrm{Cl}_2(g) \rightarrow 2\mathrm{NaCl}(s)$$, which element is oxidized and which is reduced?

Accepted Answer

Na is oxidized, Cl is reduced.

Chapter 8: Introduction to Solutions and Aqueous Reactions – Solution Concentration, Stoichiometry, and Electrolytic Properties

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