Reactions in Aqueous Solutions — Practice Quiz

A Chemistry cheat sheet for Reactions in Aqueous Solutions — every key formula with its symbols defined — plus a medium-level practice quiz to test recall.

Formulas & key concepts

Displacement Reaction: A metal (A) displaces another metal ion (B) from a salt (BX).

$$A + BX \rightarrow AX + B$$

Molarity: The number of moles of solute per liter of solution.

$$M = \frac{\text{moles solute}}{\text{volume of solution in liters}}$$

Dilution Formula: Relates the molarity and volume of concentrated and diluted solutions.

$$M_{\text{conc}} \times V_{\text{conc}} = M_{\text{dil}} \times V_{\text{dil}}$$

<table style="width:100%; border-collapse: collapse; font-size: 0.9em;"> <tr style="border-bottom: 1px solid #ccc;"><th>Metal</th><th>Oxidation Reaction</th></tr> <tr><td>Lithium (Li)</td><td>Li(s) → Li<sup>+</sup>(aq) + e<sup>-</sup></td></tr> <tr><td>Potassium (K)</td><td>K(s) → K<sup>+</sup>(aq) + e<sup>-</sup></td></tr> <tr><td>Barium (Ba)</td><td>Ba(s) → Ba<sup>2+</sup>(aq) + 2e<sup>-</sup></td></tr> <tr><td>Calcium (Ca)</td><td>Ca(s) → Ca<sup>2+</sup>(aq) + 2e<sup>-</sup></td></tr> <tr><td>Sodium (Na)</td><td>Na(s) → Na<sup>+</sup>(aq) + e<sup>-</sup></td></tr> <tr><td>Magnesium (Mg)</td><td>Mg(s) → Mg<sup>2+</sup>(aq) + 2e<sup>-</sup></td></tr> <tr><td>Aluminum (Al)</td><td>Al(s) → Al<sup>3+</sup>(aq) + 3e<sup>-</sup></td></tr> <tr><td>Manganese (Mn)</td><td>Mn(s) → Mn<sup>2+</sup>(aq) + 2e<sup>-</sup></td></tr> <tr><td>Zinc (Zn)</td><td>Zn(s) → Zn<sup>2+</sup>(aq) + 2e<sup>-</sup></td></tr> <tr><td>Chromium (Cr)</td><td>Cr(s) → Cr<sup>3+</sup>(aq) + 3e<sup>-</sup></td></tr> <tr><td>Iron (Fe)</td><td>Fe(s) → Fe<sup>2+</sup>(aq) + 2e<sup>-</sup></td></tr> <tr><td>Cobalt (Co)</td><td>Co(s) → Co<sup>2+</sup>(aq) + 2e<sup>-</sup></td></tr> <tr><td>Nickel (Ni)</td><td>Ni(s) → Ni<sup>2+</sup>(aq) + 2e<sup>-</sup></td></tr> <tr><td>Tin (Sn)</td><td>Sn(s) → Sn<sup>2+</sup>(aq) + 2e<sup>-</sup></td></tr> <tr><td>Lead (Pb)</td><td>Pb(s) → Pb<sup>2+</sup>(aq) + 2e<sup>-</sup></td></tr> <tr style="border-top: 2px solid #000;"><td><strong>Hydrogen (H<sub>2</sub>)</strong></td><td>H<sub>2</sub>(g) → 2H<sup>+</sup>(aq) + 2e<sup>-</sup></td></tr> <tr><td>Copper (Cu)</td><td>Cu(s) → Cu<sup>2+</sup>(aq) + 2e<sup>-</sup></td></tr> <tr><td>Silver (Ag)</td><td>Ag(s) → Ag<sup>+</sup>(aq) + e<sup>-</sup></td></tr> <tr><td>Mercury (Hg)</td><td>Hg(l) → Hg<sup>2+</sup>(aq) + 2e<sup>-</sup></td></tr> <tr><td>Platinum (Pt)</td><td>Pt(s) → Pt<sup>2+</sup>(aq) + 2e<sup>-</sup></td></tr> <tr><td>Gold (Au)</td><td>Au(s) → Au<sup>3+</sup>(aq) + 3e<sup>-</sup></td></tr> </table> <p style="font-size: 0.85em; margin-top: 5px;"><em>Note: Metals above hydrogen can displace H<sub>2</sub> from acids. Any metal can displace metals below it.</em></p>

$$\text{Activity Series of Metals}$$

Practice quiz

  1. Which of the following metals can displace copper from a solution of copper(II) nitrate, $Cu(NO_3)_2$?

    • A) Silver ($Ag$)
    • B) Gold ($Au$)
    • C) Zinc ($Zn$)
    • D) Platinum ($Pt$)

    Answer: C) Zinc ($Zn$)

  2. What is the molarity of a solution prepared by dissolving $0.50 \text{ moles}$ of $NaCl$ in enough water to make $0.25 \text{ liters}$ of solution?

    • A) $0.125 \text{ M}$
    • B) $0.50 \text{ M}$
    • C) $2.0 \text{ M}$
    • D) $0.25 \text{ M}$

    Answer: C) $2.0 \text{ M}$

  3. A $3.0 \text{ M}$ stock solution of $HCl$ is used to prepare $500 \text{ mL}$ of a $0.75 \text{ M}$ $HCl$ solution. What volume of the stock solution is required?

    • A) $125 \text{ mL}$
    • B) $250 \text{ mL}$
    • C) $375 \text{ mL}$
    • D) $500 \text{ mL}$

    Answer: A) $125 \text{ mL}$

  4. Which of the following reactions will NOT occur spontaneously based on the activity series?

    • A) $Mg(s) + Zn(NO_3)_2(aq) \rightarrow$
    • B) $Fe(s) + CuSO_4(aq) \rightarrow$
    • C) $Ag(s) + HCl(aq) \rightarrow$
    • D) $Al(s) + Fe_2(SO_4)_3(aq) \rightarrow$

    Answer: C) $Ag(s) + HCl(aq) \rightarrow$

  5. How many moles of $NaOH$ are present in $2.0 \text{ L}$ of a $0.50 \text{ M}$ $NaOH$ solution?

    • A) $0.25 \text{ mol}$
    • B) $0.50 \text{ mol}$
    • C) $1.0 \text{ mol}$
    • D) $2.0 \text{ mol}$

    Answer: C) $1.0 \text{ mol}$

  6. If $100 \text{ mL}$ of a $2.5 \text{ M}$ solution is diluted to a final volume of $500 \text{ mL}$, what is the new molarity?

    • A) $0.25 \text{ M}$
    • B) $0.50 \text{ M}$
    • C) $1.0 \text{ M}$
    • D) $12.5 \text{ M}$

    Answer: B) $0.50 \text{ M}$

  7. Based on the activity series, which of the following metals is the most reactive?

    • A) $Fe$
    • B) $Zn$
    • C) $Mg$
    • D) $Pb$

    Answer: C) $Mg$

  8. What volume (in liters) of a $0.10 \text{ M}$ $KNO_3$ solution contains $0.025 \text{ moles}$ of $KNO_3$?

    • A) $0.0025 \text{ L}$
    • B) $0.25 \text{ L}$
    • C) $2.5 \text{ L}$
    • D) $25 \text{ L}$

    Answer: B) $0.25 \text{ L}$

  9. Which of the following metals can displace hydrogen from an acid?

    • A) Copper ($Cu$)
    • B) Silver ($Ag$)
    • C) Gold ($Au$)
    • D) Iron ($Fe$)

    Answer: D) Iron ($Fe$)

  10. When a solution is diluted, which of the following statements is true?

    • A) The number of moles of solute increases.
    • B) The volume of the solution decreases.
    • C) The molarity of the solution decreases.
    • D) The number of moles of solvent decreases.

    Answer: C) The molarity of the solution decreases.

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