Question

Balance chemical equations: 1 Copper reacts with concentrated nitric acid 2 Calcium carbonate is treated with dilute hydrochloric acid

Answer 1

Answer:

3Cu(s) + 8HNO3(aq) → 3Cu(NO3)2(aq) + 2NO(g) + 4H2O(l)

CaCO3(s) + 2HCl (aq) → CaCl2(aq) + CO2(g) + H2O(l)  

Explanation:

3Cu(s) + 8HNO3(aq) → 3Cu(NO3)2(aq) + 2NO(g) + 4H2O(l)

Nitric oxide is a colorless gas and oxidation number of nitrogen is +2. So oxidation number of nitrogen is reduced from +5 to +2 while oxidation number of copper is increased from 0 to +2.

The following reaction takes place:

CaCO3(s) + 2HCl (aq) → CaCl2(aq) + CO2(g) + H2O(l)

The insoluble CaCO3 reacts with the dilute hydrochloric acid to produce an aqueous solution of calcium chloride , carbon dioxide gas that escapes to atmosphere and water

Answer 2

Answer:

1. Cu + 4HNO3 → Cu(NO3)2 + 2NO2 + 2H2O

2. CaCO3 + 2HCl → CaCl2 + CO2 + H2O