Q: Rank the following solutions in order of increasing electrical conductivity when 0.1 mol of each is dissolved in 1 L of water: Ca(NO$_3$)$_2$, CH$_3$COOH, CaCl$_2$, CH$_3$COONa.

CH$_3$COOH < CH$_3$COONa < CaCl$_2$ < Ca(NO$_3$)$_2$

Q: For the reaction of aqueous potassium hydride with sulfuric acid, write the balanced molecular equation and the net ionic equation, assuming both reactants are strong electrolytes and react completely.

Molecular: $\mathrm{2KH~(aq) + H_2SO_4~(aq) \rightarrow K_2SO_4~(aq) + 2H_2~(g)}$; Net ionic: $\mathrm{2H^-~(aq) + 2H^+~(aq) \rightarrow 2H_2~(g)}$

Q: Write the balanced molecular and net ionic equations for the reaction between magnesium and cobalt(II) sulfate. Which species is oxidized, and which is reduced?

Molecular: $\mathrm{Mg~(s) + CoSO_4~(aq) \rightarrow MgSO_4~(aq) + Co~(s)}$; Net ionic: $\mathrm{Mg~(s) + Co^{2+}~(aq) \rightarrow Mg^{2+}~(aq) + Co~(s)}$; Mg is oxidized, Co$^{2+}$ is reduced.

Q: Order these compounds from minimum to maximum oxidation number for iron: FeO, Fe, FeCl$_3$, Fe$_2$O$_3$.

Fe < FeO < Fe$_2$O$_3$ < FeCl$_3$

Q: Which of the following reactions is a redox reaction?

$\mathrm{Mg~(s) + CoSO_4~(aq) \rightarrow MgSO_4~(aq) + Co~(s)}$

Q: Which of the following best describes the role of a spectator ion in a chemical reaction?

It remains unchanged and does not participate directly in the reaction.

Question 1

If you were to draw diagrams representing aqueous solutions of (a) NiSO$_4$, (b) Ca(NO$_3$)$_2$, (c) Na$_3$PO$_4$, and (d) Al$_2$(SO$_4$)$_3$, how many anions would you show if each diagram contained six cations?

Accepted Answer

For (a) 6, (b) 3, (c) 2, (d) 9

Question 2

What compound precipitates when aqueous solutions of FeSO$_4$ and LiOH are mixed? Write a balanced equation for the reaction.

Accepted Answer

Fe(OH)$_2$; $\mathrm{FeSO_4~(aq) + 2~LiOH~(aq) \rightarrow Fe(OH)_2~(s) + Li_2SO_4~(aq)}$

Question 3

Rank the following solutions in order of increasing electrical conductivity when 0.1 mol of each is dissolved in 1 L of water: Ca(NO$_3$)$_2$, CH$_3$COOH, CaCl$_2$, CH$_3$COONa.

Accepted Answer

CH$_3$COOH < CH$_3$COONa < CaCl$_2$ < Ca(NO$_3$)$_2$

Question 4

For the reaction of aqueous potassium hydride with sulfuric acid, write the balanced molecular equation and the net ionic equation, assuming both reactants are strong electrolytes and react completely.

Accepted Answer

Molecular: $\mathrm{2KH~(aq) + H_2SO_4~(aq) \rightarrow K_2SO_4~(aq) + 2H_2~(g)}$; Net ionic: $\mathrm{2H^-~(aq) + 2H^+~(aq) \rightarrow 2H_2~(g)}$

Question 5

Write the balanced molecular and net ionic equations for the reaction between magnesium and cobalt(II) sulfate. Which species is oxidized, and which is reduced?

Accepted Answer

Molecular: $\mathrm{Mg~(s) + CoSO_4~(aq) \rightarrow MgSO_4~(aq) + Co~(s)}$; Net ionic: $\mathrm{Mg~(s) + Co^{2+}~(aq) \rightarrow Mg^{2+}~(aq) + Co~(s)}$; Mg is oxidized, Co$^{2+}$ is reduced.

Question 6

Order these compounds from minimum to maximum oxidation number for iron: FeO, Fe, FeCl$_3$, Fe$_2$O$_3$.

Accepted Answer

Fe < FeO < Fe$_2$O$_3$ < FeCl$_3$

Question 7

If a compound in which Mn is initially in the +2 oxidation state in aqueous solution is reduced, what might the product contain?

Accepted Answer

Mn(s)

Question 8

How many grams of Na$_2$SO$_3$ are there in 15 mL of 0.50 M Na$_2$SO$_3$?

Accepted Answer

0.53 g

Question 9

What is the molarity of a NaOH solution if 48.0 mL neutralizes 35.0 mL of 0.144 M H$_2$SO$_4$?

Accepted Answer

0.105 M

Question 10

A sample of an iron ore is dissolved in acid and the iron is converted to Fe$^{2+}$. The sample is then titrated with 47.20 mL of 0.02240 M MnO$_4^-$. How many moles of MnO$_4^-$ were added to the solution?

Accepted Answer

$0.00106~\mathrm{mol}$

Question 11

In the titration of Fe$^{2+}$ with MnO$_4^-$, how many moles of Fe$^{2+}$ were in the sample if 47.20 mL of 0.02240 M MnO$_4^-$ were used? (Use the reaction: $\mathrm{MnO_4^- + 5~Fe^{2+} + 8~H^+ \rightarrow Mn^{2+} + 5~Fe^{3+} + 4~H_2O}$)

Accepted Answer

$0.00530~\mathrm{mol}$

Question 12

How many grams of iron were in the sample if 0.00530 mol of Fe$^{2+}$ were present?

Accepted Answer

0.296 g

Question 13

If the sample had a mass of 0.8890 g, what is the percentage of iron in the sample if it contained 0.296 g of iron?

Accepted Answer

33.3%

Question 14

Which of the following is a strong electrolyte in aqueous solution?

Accepted Answer

Ca(NO$_3$)$_2$

Question 15

Which of the following reactions is a redox reaction?

Accepted Answer

$\mathrm{Mg~(s) + CoSO_4~(aq) \rightarrow MgSO_4~(aq) + Co~(s)}$

Question 16

Which of the following ions would you expect to have the highest conductivity in water?

Accepted Answer

Cl$^-$

Question 17

A solution contains 0.1 mol of CaCl$_2$ in 1 L of water. How many total ions are present in the solution?

Accepted Answer

0.3 mol

Question 18

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

Accepted Answer

It remains unchanged and does not participate directly in the reaction.

Exam 2 Chapter 4 Review

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