Problem 28 - Chemistry An Atoms First Approach

Question

Commercial cold packs and hot packs are available for treating athletic injuries. Both types contain a pouch of water and a dry chemical. When the pack is struck, the pouch of water breaks, dissolving the chemical, and the solution becomes either hot or cold. Many hot packs use magnesium sulfate, and many cold packs use ammonium nitrate. Write reactions to show how these strong electrolytes break apart when they dissolve in water.

Step-by-Step Solution

Answer

The dissociation reactions of magnesium sulfate (MgSO₄) and ammonium nitrate (NH₄NO₃) in water are as follows: For magnesium sulfate: \[MgSO_4(s) \rightarrow Mg^{2+}(aq) + SO_4^{2-}(aq)\] For ammonium nitrate: \[NH_4NO_3(s) \rightarrow NH_4^+(aq) + NO_3^-(aq)\]

Step 1: Write the chemical formulas for magnesium sulfate and ammonium nitrate

Magnesium sulfate has the chemical formula MgSO₄, while ammonium nitrate has the chemical formula NH₄NO₃.

Step 2: Write the dissociation reaction for magnesium sulfate in water

When magnesium sulfate (MgSO₄) dissolves in water, it separates into magnesium ions (Mg²⁺) and sulfate ions (SO₄²⁻). The balanced dissociation reaction is: \[MgSO_4(s) \rightarrow Mg^{2+}(aq) + SO_4^{2-}(aq)\]

Step 3: Write the dissociation reaction for ammonium nitrate in water

When ammonium nitrate (NH₄NO₃) dissolves in water, it separates into ammonium ions (NH₄⁺) and nitrate ions (NO₃⁻). The balanced dissociation reaction is: \[NH_4NO_3(s) \rightarrow NH_4^+(aq) + NO_3^-(aq)\] This completes the step-by-step solution for the dissociation reactions of magnesium sulfate and ammonium nitrate in water.