Question

Write a balanced chemical equation to describe how magnesium ions are removed in water treatment by the addition of slaked lime, \(\mathrm{Ca}(\mathrm{OH})_{2}\).

Short answer

The balanced chemical equation for the removal of magnesium ions in water treatment by the addition of slaked lime, \(\mathrm{Ca}(\mathrm{OH})_{2}\), is: \[2\mathrm{Mg}^{2+} + \mathrm{Ca}(\mathrm{OH})_2 \rightarrow 2\mathrm{Mg}(\mathrm{OH})_2 + \mathrm{Ca}^{2+}\]

Step-by-step solution

Identify the Reactants

In this reaction, the reactants are magnesium ions in water (suppose as \(\mathrm{Mg}^{2+}\)) and slaked lime, \(\mathrm{Ca}(\mathrm{OH})_{2}\).

Write the Unbalanced Reaction

In this step, we combine the reactants to form the products. Calcium in \(\mathrm{Ca}(\mathrm{OH})_{2}\) will react with magnesium ions to form solid magnesium hydroxide \(\mathrm{Mg}(\mathrm{OH})_{2}\) and aqueous calcium ions \(\mathrm{Ca}^{2+}\). The unbalanced reaction is: \(\mathrm{Mg}^{2+} + \mathrm{Ca}(\mathrm{OH})_2 \rightarrow \mathrm{Mg}(\mathrm{OH})_2 + \mathrm{Ca}^{2+}\)

Balance the Chemical Equation

We will now balance the chemical equation, ensuring the number of atoms of each element is the same on both sides of the equation. There are equal numbers of magnesium, calcium, and oxygen atoms on both sides of the equation, but the number of hydrogen atoms is not equal. We need to balance the hydrogen atoms by multiplying the \(\mathrm{Mg}^{2+}\) ions by 2. Balanced chemical equation: \(2\mathrm{Mg}^{2+} + \mathrm{Ca}(\mathrm{OH})_2 \rightarrow 2\mathrm{Mg}(\mathrm{OH})_2 + \mathrm{Ca}^{2+}\) Now, the number of atoms for each element is the same on both sides. The balanced chemical equation is: \[2\mathrm{Mg}^{2+} + \mathrm{Ca}(\mathrm{OH})_2 \rightarrow 2\mathrm{Mg}(\mathrm{OH})_2 + \mathrm{Ca}^{2+}\]