Balance the following chemical reactions: Sodium + water, Calcium + water, Potassium + water.

To balance the hydrogen atoms, place a coefficient of 2 in front of H$_2$O and NaOH. Then balance sodium.

$$\boxed{\text{2Na(s)} + \text{2H}_{2}\text{O(l)} \rightarrow \text{2NaOH(aq)} + \text{H}_{2}\text{(g)}}$$

29) Calcium + water $\rightarrow$ calcium hydroxide + hydrogen gas

To balance the oxygen and hydrogen atoms, place a coefficient of 2 in front of H$_2$O.

$$\boxed{\text{Ca(s)} + \text{2H}_{2}\text{O(l)} \rightarrow \text{Ca(OH)}_{2}\text{(aq)} + \text{H}_{2}\text{(g)}}$$

30) Potassium + water $\rightarrow$ potassium hydroxide + hydrogen gas

To balance the hydrogen atoms, place a coefficient of 2 in front of H$_2$O and KOH. Then balance potassium.

$$\boxed{\text{2K(s)} + \text{2H}_{2}\text{O(l)} \rightarrow \text{2KOH(aq)} + \text{H}_{2}\text{(g)}}$$