Question

State and explain Gay Lussacs law of combining volumes

Answer 1

1️⃣The Gay Lussac law of Gaseous volumes was given by Joseph Gay Lussac in the year 1808.

2️⃣According to this law, in a chemical reaction involving gaseous reactants or products, the volumes of the gases can be expressed in simple whole number ratio provided all the gases are at the same temperature and pressure.

For example,

The reaction between nitrogen and hydrogen is written as N2 (g) + 3 H2 (g) →2 NH3(g)We can see that the volumes of N2, H2 and NH3 are actually involved in simple whole number ratios that is N2: H2: NH3 = 1 : 3 : 2

Another example is 2 H2(g) + O2 (g) →2 H2O (l)

Here 2 volumes of Hydrogen combine with 1 volume of Oxygen to form 2 volumes of water. Again, H2 and O2 combine in simple integer ratio (2: 1) to form 2 volumes of water.

✔️Also note that Gay Lussac’s law of integer ratio in volume relationship of combining gases is actually the law of definite proportion by volume (i.e. gases are combining in fixed whole number ratio).

Answer 2

When gases react they do so in volumes which bears a simple whole number ratio to one another and to the volumes of the products, if gaseous, provided the temperature and pressure of the reacting gases and their products remain constant.