Question

What happens carbon dioxide gas is bubbled through lime water:

1. In small amount
2. In excess

Answer 1

Step 1: Carbon dioxide gas is bubbled through lime water in a small amount

• Calcium hydroxide$\left(\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\right)$ is also called lime water.
• When carbon dioxide gas is bubbled through lime water in a small amount, it forms milky calcium carbonate (${\mathrm{CaCO}}_3$).
• Calcium hydroxide + Carbon dioxide = Calcium carbonate + Water

$\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\left(\mathrm{aq}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)\to {\mathrm{CaCO}}_3\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}$

Step 2: Carbon dioxide gas is bubbled through lime water in excess

• When carbon dioxide gas is added in the excess amount it forms colourless calcium bicarbonate $\mathrm{Ca}{\left({\mathrm{HCO}}_3\right)}_2$.
• Calcium carbonate + Carbon dioxide + Water = Calcium bicarbonate

${\mathrm{CaCO}}_3\left(\mathrm{aq}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to \mathrm{Ca}{\left({\mathrm{HCO}}_3\right)}_2\left(\mathrm{s}\right)$