Chemistry » Physical and Chemical Change » Law Of Constant Composition

# Volume Relationships in Gases

## Volume Relationships in Gases

In a chemical reaction between gases, the relative volumes of the gases in the reaction are present in a ratio of small whole numbers if all the gases are at the same temperature and pressure. This relationship is also known as Gay-Lussac’s Law.

For example, in the reaction between hydrogen and oxygen to produce water, two volumes of $$\text{H}_{2}$$ react with 1 volume of $$\text{O}_{2}$$ to produce 2 volumes of $$\text{H}_{2}\text{O}$$.

$2\text{H}_{2}\text{(g)} + \text{O}_{2}\text{(g)} \rightarrow 2\text{H}_{2}\text{O (l)}$

In the reaction to produce ammonia, one volume of nitrogen gas reacts with three volumes of hydrogen gas to produce two volumes of ammonia gas.

$\text{N}_{2}\text{(g)} + 3\text{H}_{2}\text{(g)} \rightarrow 2\text{NH}_{3}\text{(g)}$