5. \( \because \mathrm{CaO}+\sum \mathrm{HCl} \rightarrow+\mathrm{CaCl}_{2}+\sum \mathrm{H}_{2} \mathrm{O} \)

To balance the chemical equation given: \[ \mathrm{CaO} + \sum \mathrm{HCl} \rightarrow \mathrm{CaCl}_{2} + \sum \mathrm{H}_{2} \mathrm{O} \] Let's break it down step by step. 1. **Identify the reactants and products:** - Reactants: Calcium oxide (\(\mathrm{CaO}\)) and hydrochloric acid (\(\mathrm{HCl}\)). - Products: Calcium chloride (\(\mathrm{CaCl}_{2}\)) and water (\(\mathrm{H}_{2}\mathrm{O}\)). 2. **Write the unbalanced equation:** \[ \mathrm{CaO} + \mathrm{HCl} \rightarrow \mathrm{CaCl}_{2} + \mathrm{H}_{2}\mathrm{O} \] 3. **Count the number of atoms for each element on both sides:** - Left side: - Ca: 1 (from \(\mathrm{CaO}\)) - O: 1 (from \(\mathrm{CaO}\)) - H: 1 (from \(\mathrm{HCl}\)) - Cl: 1 (from \(\mathrm{HCl}\)) - Right side: - Ca: 1 (from \(\mathrm{CaCl}_{2}\)) - O: 1 (from \(\mathrm{H}_{2}\mathrm{O}\)) - H: 2 (from \(\mathrm{H}_{2}\mathrm{O}\)) - Cl: 2 (from \(\mathrm{CaCl}_{2}\)) 4. **Balance the equation:** - We see that we have 2 chlorine atoms on the right side, so we need 2 \(\mathrm{HCl}\) on the left side. - We also have 2 hydrogen atoms on the right side, which matches with 2 \(\mathrm{HCl}\). 5. **Update the equation:** \[ \mathrm{CaO} + 2 \mathrm{HCl} \rightarrow \mathrm{CaCl}_{2} + \mathrm{H}_{2}\mathrm{O} \] 6. **Final check:** - Left side: - Ca: 1 - O: 1 - H: 2 - Cl: 2 - Right side: - Ca: 1 - O: 1 - H: 2 - Cl: 2 Both sides are balanced. The balanced chemical equation is: \[ \mathrm{CaO} + 2 \mathrm{HCl} \rightarrow \mathrm{CaCl}_{2} + \mathrm{H}_{2}\mathrm{O} \]