Question 1

What is the molarity of a solution prepared by dissolving 10.19 g of ethanol ($$\mathrm{CH_3CH_2OH}$$, molar mass = 46.07 g/mol) in enough water to produce 250.0 mL of solution?

Accepted Answer

$$0.885\ \mathrm{M}$$

Question 2

A 375 mL sample of $$0.250\ \mathrm{M}$$ magnesium chloride ($$\mathrm{$$MgCl_2$$}) is $$prepared. What is the mass of chloride ions present in the solution? (Molar mass of Cl = 35.45 g/mol)

Accepted Answer

$$6.66\ \mathrm{g}$$

Question 3

What volume of a $$2.00\ \mathrm{M}$$ stock solution of NaOH is required to prepare $$50.0\ \mathrm{mL} of a$$ $$0.400\ \mathrm{M}$$ solution?

Accepted Answer

$$10.0\ \mathrm{mL}$$

Question 4

What volume of $$0.250\ \mathrm{M}$$ HCl is needed to react completely with $$25.00\ \mathrm{mL} of$$ $$0.375\ \mathrm{M}$$ $$\mathrm{Na_2CO_3}$$? (Reaction: $$2\mathrm{HCl} + \mathrm{Na_2CO_3} \rightarrow 2\mathrm{NaCl} + \mathrm{CO_2$} + \mathrm{H_2O})$$

Accepted Answer

$$75.0\ \mathrm{mL}$$

Question 5

In a titration, $$22.35\ \mathrm{mL} of$$ $$\mathrm{$$KMnO_4$$}$$ solution reacts with $$0.5170\ \mathrm{g} of $$oxalic acid ($$\mathrm{H_2C_2O_4}$$, molar mass = 90.03 g/mol) according to the equation:

$$5\mathrm{H_2C_2O_4} + 2\mathrm{$$KMnO_4$$} + 3\mathrm{H_2SO_4} \rightarrow 10\mathrm{CO_2$} + 2\mathrm{$$MnSO_4$$} + \mathrm{K_2SO_4} + 8\mathrm{H_2O}$$

What is the concentration of the $$\mathrm{$$KMnO_4$$}$$ solution?

Accepted Answer

$$0.0520\ \mathrm{M}$$

Question 6

Which of the following is the correctly balanced redox reaction for the oxidation of copper by nitrate ion under acidic conditions?

$$\mathrm{Cu} (s) + \mathrm{NO_3$^-} (aq) \rightarrow \mathrm{NO} (g) + \mathrm{Cu$$^{2+}$$} (aq)$$

Accepted Answer

$$3\mathrm{Cu} (s) + 2\mathrm{NO_3$^-} (aq) + 8\mathrm{H^+} (aq) \rightarrow 3\mathrm{Cu$$^{2+}$$} (aq) + 2\mathrm{NO} (g) + 4\mathrm{H_2O} (l)$$

Question 7

Which of the following is the correct net ionic equation for the reaction between $$\mathrm{Na_2CO_3}$$ and $$\mathrm{HCl}$$?

Accepted Answer

$$\mathrm{CO_3$^{2-}} (aq) + 2\mathrm{H^+} (aq) \rightarrow \mathrm{CO_2$} (g) + \mathrm{H_2O} (l)$$

Question 8

A solution is prepared by diluting $$10.0\ \mathrm{mL} of$$ $$6.00\ \mathrm{M}$$ HCl to a final volume of $$250.0\ \mathrm{mL}. $$What is the final concentration of HCl?

Accepted Answer

$$0.240\ \mathrm{M}$$

Question 9

Which of the following best describes the role of $$\mathrm{H_2SO_4} in $$the titration reaction between $$\mathrm{$$KMnO_4$$}$$ and $$\mathrm{H_2C_2O_4}$$?

Accepted Answer

It provides an acidic environment necessary for the redox reaction to proceed.

Question 10

Which of the following is the correctly balanced redox reaction for the reaction of $$\mathrm{Cr_2O_7$$^{2-}$$}$$ with $$\mathrm{Fe$$^{2+}$$}$$ under acidic conditions?

Accepted Answer

$$\mathrm{Cr_2O_7$$^{2-}$$} (aq) + 6\mathrm{Fe$$^{2+}$$} (aq) + 14\mathrm{H^+} (aq) \rightarrow 2\mathrm{Cr$$^{3+}$$} (aq) + 6\mathrm{Fe$$^{3+}$$} (aq) + 7\mathrm{H_2O} (l)$$

Question 11

Which of the following is the correct balanced equation for the reaction of $$\mathrm{$$ClO_2$$^-}$$ with $$\mathrm{OH^-} in $$basic solution?

Accepted Answer

$$2\mathrm{$$ClO_2$$^-} (aq) + 2\mathrm{OH^-} (aq) \rightarrow \mathrm{$$ClO_3$$^-} (aq) + \mathrm{Cl^-} (aq) + \mathrm{H_2O} (l)$$

Question 12

A laboratory technician needs to prepare $$100.0\ \mathrm{mL} of$$ $$0.500\ \mathrm{M}$$ $$\mathrm{Na_2SO_4}$$ solution. What mass of $$\mathrm{Na_2SO_4} ($$molar mass = 142.04 g/mol) is required?

Accepted Answer

$$7.10\ \mathrm{g}$$

Question 13

A $$25.00\ \mathrm{mL}$$ sample of $$0.200\ \mathrm{M}$$ $$\mathrm{H_2SO_4} is $$titrated with $$0.100\ \mathrm{M}$$ NaOH. What volume of NaOH is required to reach the equivalence point? (Reaction: $$\mathrm{H_2SO_4} + 2\mathrm{NaOH} \rightarrow \mathrm{Na_2SO_4} + 2\mathrm{H_2O})$$

Accepted Answer

$$100.0\ \mathrm{mL}$$

Question 14

Which of the following statements best explains why $$\mathrm{$$KMnO_4$$} is a $$good oxidizing agent in acidic solution?

Accepted Answer

Manganese in $$\mathrm{$$KMnO_4$$}$$ has a high oxidation state and readily accepts electrons, being reduced from $$\mathrm{Mn$$^{7+}$$} to$$ $$\mathrm{Mn$$^{2+}$$}.$$

Question 15

A student accidentally adds excess $$\mathrm{HCl} to a $$solution containing $$\mathrm{Na_2CO_3}. $$What gas is evolved, and what is the balanced equation for its formation?

Accepted Answer

Carbon dioxide; $$\mathrm{CO_3$^{2-}} (aq) + 2\mathrm{H^+} (aq) \rightarrow \mathrm{CO_2$} (g) + \mathrm{H_2O} (l)$$

Question 16

Which of the following best describes the function of a titration in analytical chemistry?

Accepted Answer

To determine the concentration of an unknown solution by reacting it with a solution of known concentration.

General Chemistry Chapter 4 Worksheet Guidance: Solutions, Molarity, and Redox Balancing

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