Question

2 L of $H_2$ and 2L of $O_2$ are mixed at ${10}^{o}C$ and L-atm. An electric spark is passed through the mixture, upon which there is a 'pop'. On bringing back the temperature and pressure to the original values, will there be any gas(es) left? If the answer is yes, what will be their volumes?

• A. 2 : 1 : 2, 1 litre of oxygen is left
• B. 1 : 1 : 2, no gas is left
• C. 2 : 1 : 3, 1 litre of oxygen is left
• D. 2 : 1 : 2, no gas is left

Answer 1

Answer: (A)

2 : 1 : 2, 1 litre of oxygen is left

${2H}_2+O_2\stackrel{electric}{\underset{spark}{⟶}}2H_{2}O$

Volume ratio $=2:1:2$

$\Rightarrow 2l$ of $H_2$ reacts with $1l$ of $O_2$ to form $2l$ of $H_{2}O$

$\therefore$ $1l$ of $O_2$ is consumed and $O_2$ left $=1l$.