This is a **precipitation** reaction: **CaCO3** is the formed precipitate.

This is a **gas evolution** reaction, **CO2** is the formed gas.

### Input interpretation

*Ca(HCO3)2 → CaCO3 + CO2 + H2O*

*Calcium carbonate carbon dioxide water*

### Balanced equation

Balance the chemical equation algebraically:

*Ca(HCO3)2 → CaCO3 + CO2 + H2O*

Add stoichiometric coefficients, c, to the reactants and products:

*c1Ca(HCO3)2 → c2CaCO3 + c3CO2 + c4H2O*

Set the number of atoms in the reactants equal to the number of atoms in the products for ** Ca, H, C **and

*O:**Ca: c1 = c2*

*H: 2c1 = 2c4*

*C: 2c1 = c2 + c3*

*O: 6c1 = 3c2 + 2c3 + c4*

Since the coefficients are relative quantities and underdetermined, choose a coefficient to set arbitrarily. To keep the coefficients small, the arbitrary value is ordinarily one. For instance, set c1 = 1 and solve the system of equations for the remaining coefficients:

*c1 = 1 c2=1*

*c3 = 1 c4=1*

Substitute the coefficients into the chemical reaction to obtain the balanced

equation:

**Answer**:

*Ca(HCO3)2 → CaCO3 + CO2 + H2O*