Q: A solution is prepared 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)

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

Q: A student wants to prepare 250 mL of a 1.50 M KBr solution. What mass of KBr is required? (Molar mass of KBr = 119.00 g/mol)

$$\text{mass} = 1.50\ \mathrm{mol/L} \times 0.250\ \mathrm{L} \times 119.00\ \mathrm{g/mol} = 44.6\ \mathrm{g}$$

Q: A titration of 10.00 mL of HCl solution of unknown concentration requires 12.54 mL of a 0.100 M NaOH solution to reach the equivalence point. What is the concentration of the HCl solution?

$$M_{\mathrm{HCl}} = \dfrac{0.100\ \mathrm{mol/L} \times 0.01254\ \mathrm{L}}{0.01000\ \mathrm{L}} = 0.125\ \mathrm{M}$$

Question 1

A solution is prepared 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

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

Question 2

Which of the following statements about molarity is correct?

Accepted Answer

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

Question 3

How many liters of a 0.125 M NaOH solution are required to contain 0.255 mol of NaOH?

Accepted Answer

$$V = \dfrac{0.255\ \mathrm{mol}}{0.125\ \mathrm{mol/L}} = 2.04\ \mathrm{L}$$

Question 4

A student wants to prepare 250 mL of a 1.50 M KBr solution. What mass of KBr is required? (Molar mass of KBr = 119.00 g/mol)

Accepted Answer

$$	ext{mass} = 1.50\ \mathrm{mol/L} 	imes 0.250\ \mathrm{L} 	imes 119.00\ \mathrm{g/mol} = 44.6\ \mathrm{g}$$

Question 5

What volume should you dilute 0.200 L of a 15.0 M NaOH solution to in order to obtain a 3.00 M NaOH solution?

Accepted Answer

$$V_2$$ = \dfrac{$$M_1$$ $$V_1$$}{$$M_2$$} = \dfrac{15.0\ \mathrm{M} 	imes 0.200\ \mathrm{L}}{3.00\ \mathrm{M}} = 1.00\ \mathrm{L}$$

Question 6

Which compound is insoluble in water according to the solubility rules?

Accepted Answer

BaSO$$_4$$

Question 7

What is the net ionic equation for the reaction between aqueous HCl and aqueous NaOH?

Accepted Answer

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

Question 8

A titration of 10.00 mL of HCl solution of unknown concentration requires 12.54 mL of a 0.100 M NaOH solution to reach the equivalence point. What is the concentration of the HCl solution?

Accepted Answer

$$M_{\mathrm{HCl}} = \dfrac{0.100\ \mathrm{mol/L} 	imes 0.01254\ \mathrm{L}}{0.01000\ \mathrm{L}} = 0.125\ \mathrm{M}$$

Question 9

Which of the following reactions will result in a precipitate when aqueous solutions are mixed?

Accepted Answer

$$\mathrm{K}_2\mathrm{CO}_3(aq) + \mathrm{NiCl}_2(aq) \rightarrow \mathrm{NiCO}_3(s) + 2\mathrm{KCl}(aq)$$

Question 10

Assign the oxidation state to sulfur in SO$$_4$$^{2-}$$.

Accepted Answer

$$+6$$

Question 11

In the reaction $$\mathrm{Mg}(s) + 2\mathrm{H}_2\mathrm{O}(l) \rightarrow \mathrm{Mg(OH)}_2(aq) + \mathrm{H}_2(g)$$, which element is oxidized and which is reduced?

Accepted Answer

Mg is oxidized, H is reduced.

Question 12

Which of the following is a redox reaction?

Accepted Answer

$$\mathrm{Zn}(s) + \mathrm{Fe}^{2+}(aq) \rightarrow \mathrm{Zn}^{2+}(aq) + \mathrm{Fe}(s)$$

Question 13

Which compound is always soluble in water?

Accepted Answer

NaNO$$_3$$

Question 14

What is the net ionic equation for the reaction between acetic acid (HC$$_2H$_3O$_2) $$and potassium hydroxide (KOH)?

Accepted Answer

$$\mathrm{HC}_2\mathrm{H}_3\mathrm{O}_2(aq) + \mathrm{OH}^-(aq) \rightarrow \mathrm{H}_2\mathrm{O}(l) + \mathrm{C}_2\mathrm{H}_3\mathrm{O}_2^-(aq)$$

Question 15

A gas-evolution reaction occurs when aqueous nitric acid reacts with sodium carbonate. What is the balanced molecular equation for this reaction?

Accepted Answer

$$2\mathrm{HNO}_3(aq) + \mathrm{Na}_2\mathrm{CO}_3(aq) \rightarrow \mathrm{H}_2\mathrm{O}(l) + \mathrm{CO}_2(g) + 2\mathrm{NaNO}_3(aq)$$

Question 16

Which of the following reactions is spontaneous based on the activity series?

Accepted Answer

$$\mathrm{Fe}(s) + \mathrm{Pb}^{2+}(aq) \rightarrow \mathrm{Fe}^{2+}(aq) + \mathrm{Pb}(s)$$

Chapter 5: Introduction to Solutions and Aqueous Reactions – Solution Concentration and Molarity Calculations

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