Question

question 8 of 10
what has a complete ionic equation of
mg(s) + zn²⁺ + 2no₃⁻ → mg²⁺ + 2no₃⁻ + zn(s)?

a. mg(no₃)₂ + zn(s) → zn²⁺ + 2no₃⁻ + mg(s)

b. mg(s) + zn²⁺ → mg²⁺ + zn(s)

c. mg(s) + zn(no₃)₂(aq) → mg(no₃)₂(aq) + zn(s)

d. mg(s) + 2zn(no₃)(aq) → 2mgno₃(aq) + zn(s)

Explanation:

To solve this, we analyze the complete ionic equation and the options:

Step 1: Identify Spectator Ions

In the given complete ionic equation \( \text{Mg}(s) + \text{Zn}^{2+} + 2\text{NO}_3^-
ightarrow \text{Mg}^{2+} + 2\text{NO}_3^- + \text{Zn}(s) \), the \( \text{NO}_3^- \) ions appear on both sides. These are spectator ions (they don't participate in the reaction) and can be removed to get the net ionic equation.

Step 2: Analyze Each Option

• Option A: The reactants and products are reversed, and the reaction direction is wrong. The original equation has Mg reacting to form \( \text{Mg}^{2+} \), but this option has Zn reacting to form \( \text{Zn}^{2+} \) which is incorrect.
• Option B: This is the net ionic equation (removing spectator ions \( \text{NO}_3^- \)), but the question asks for the reaction that has the given complete ionic equation. We need the molecular equation (or the reaction with the correct compounds).
• Option C: The molecular equation here is \( \text{Mg}(s) + \text{Zn(NO}_3\text{)}_2(aq)

ightarrow \text{Mg(NO}_3\text{)}_2(aq) + \text{Zn}(s) \). When we write the complete ionic equation for this, \( \text{Zn(NO}_3\text{)}_2(aq) \) dissociates into \( \text{Zn}^{2+} + 2\text{NO}_3^- \) and \( \text{Mg(NO}_3\text{)}_2(aq) \) dissociates into \( \text{Mg}^{2+} + 2\text{NO}_3^- \). So the complete ionic equation becomes \( \text{Mg}(s) + \text{Zn}^{2+} + 2\text{NO}_3^-
ightarrow \text{Mg}^{2+} + 2\text{NO}_3^- + \text{Zn}(s) \), which matches the given complete ionic equation.

• Option D: The formula for zinc nitrate is \( \text{Zn(NO}_3\text{)}_2 \) (not \( \text{Zn(NO}_3\text{)} \)) and magnesium nitrate is \( \text{Mg(NO}_3\text{)}_2 \) (not \( \text{MgNO}_3 \)). The formulas are incorrect.

Answer:

C. \( \text{Mg}(s) + \text{Zn(NO}_3\text{)}_2(aq)
ightarrow \text{Mg(NO}_3\text{)}_2(aq) + \text{Zn}(s) \)