Question

Explain why two liters of hydrogen gas and one liter of oxygen gas react to form two liters of water, when the pressures and temperatures are held constant.

Answer 1

Answer: In accordance to Avogadro's law, two liters of hydrogen gas and one liter of oxygen gas react to form two liters of water.

Explanation:

The relationship of number of moles and volume at constant temperature and pressure was given by Avogadro's law. This law states that volume is directly proportional to number of moles at constant temperature and pressure.

Mathematically,

$V\propto n$      (at constant pressure and temperature)

The chemical equation for the formation of water molecule follows:

$2H_2+O_2\rightarrow 2H_2O$

The mole ratio of $H_2:O_2:H_2O$ is 2 : 1 : 2

The volume ratio of $H_2:O_2:H_2O$ will also be 2 : 1 : 2

We are given:

Volume of hydrogen gas = 2 L

Volume of oxygen gas = 1 L

Volume of water = 2 L

So, the volume ratio of $H_2:O_2:H_2O$ is 2 : 1 : 2

Hence, in accordance to Avogadro's law, two liters of hydrogen gas and one liter of oxygen gas react to form two liters of water.