1.1 Solved examples

  Balancing Reaction

Question: Balance the following equation:
$$N{a_{(s)}} + {H_2}{O_{(l)}} \to NaO{H_{(aq)}} + {H_{2(g)}}$$
Solution: First balance hydrogen on both side of the reaction as below,
$$N{a_{(s)}} + 2{H_2}{O_{(l)}} \to 2NaO{H_{(aq)}} + {H_{2(g)}}$$
While balacing hydrogen, oxygen is automatically balanced.

So, now we have to only balance sodium.
$$2N{a_{(s)}} + 2{H_2}{O_{(l)}} \to 2NaO{H_{(aq)}} + {H_{2(g)}}$$
Now, the above equation is balanced.

Question: Balance the following equation:
$${P_2}{O_5}_{(s)} + {H_2}{O_{(l)}} \to {H_3}P{O_4}_{(aq)}$$

Solution: First balance the hydrogen.
$${P_2}{O_5}_{(s)} + 3{H_2}{O_{(l)}} \to 2{H_3}P{O_4}_{(aq)}$$
In the above equation we notice that oxygen, phosphorous is also balanced.