What is the balanced chemical equation between magnesium and
a. hydrochloric acid
b. citric acid
c. ammonium chloride
The correct answer and explanation is:
The reactions between magnesium and the three substances will each yield different products. Let’s break down each case:
a. Magnesium and Hydrochloric Acid (HCl):
The reaction between magnesium and hydrochloric acid produces magnesium chloride (MgCl₂) and hydrogen gas (H₂). The balanced chemical equation is: Mg(s)+2HCl(aq)→MgCl2(aq)+H2(g)\text{Mg} (s) + 2 \text{HCl} (aq) \rightarrow \text{MgCl}_2 (aq) + \text{H}_2 (g)
Explanation:
In this reaction, magnesium reacts with hydrochloric acid to form magnesium chloride and hydrogen gas. The magnesium metal donates electrons to hydrogen ions (H⁺) from hydrochloric acid. This results in the reduction of hydrogen ions to hydrogen gas (H₂) and the oxidation of magnesium to form magnesium ions (Mg²⁺), which combine with chloride ions (Cl⁻) to form magnesium chloride (MgCl₂).
b. Magnesium and Citric Acid (C₆H₈O₇):
When magnesium reacts with citric acid, it forms magnesium citrate (Mg₃(C₆H₅O₇)₂) and hydrogen gas. The balanced equation is: 3Mg(s)+2C6H8O7(aq)→Mg3(C6H5O7)2(aq)+3H2(g)3 \text{Mg} (s) + 2 \text{C}_6\text{H}_8\text{O}_7 (aq) \rightarrow \text{Mg}_3(\text{C}_6\text{H}_5\text{O}_7)_2 (aq) + 3 \text{H}_2 (g)
Explanation:
In this reaction, magnesium metal reacts with citric acid to produce magnesium citrate, which is a salt, and hydrogen gas. Magnesium displaces the hydrogen ions (H⁺) from citric acid, leading to the formation of hydrogen gas and magnesium citrate. The stoichiometry of the reaction involves 3 magnesium atoms for every 2 citric acid molecules, which is required to balance the equation.
c. Magnesium and Ammonium Chloride (NH₄Cl):
The reaction between magnesium and ammonium chloride typically forms magnesium chloride and ammonia gas (NH₃). The balanced equation is: Mg(s)+2NH4Cl(aq)→MgCl2(aq)+2NH3(g)+H2(g)\text{Mg} (s) + 2 \text{NH}_4\text{Cl} (aq) \rightarrow \text{MgCl}_2 (aq) + 2 \text{NH}_3 (g) + \text{H}_2 (g)
Explanation:
Magnesium reacts with ammonium chloride, causing the magnesium to displace hydrogen ions from the ammonium ions (NH₄⁺). This produces ammonia gas (NH₃) and hydrogen gas (H₂), along with magnesium chloride. The hydrogen gas is released as a result of the magnesium being oxidized, while the ammonia gas is produced by the reduction of ammonium ions.
These reactions are typical of magnesium’s reactivity with acids, where it often produces hydrogen gas and a corresponding salt.