Explain with diagram the method for preparation of hydrogen gas in laboratory.

The hydrogen gas can be prepared by the reaction of metal with dilute acid or water.

Preparation of hydrogen gas from zinc metals with dilute acid:

i. In labs, pieces of zinc metals are taken in a flask.

ii. Dilute sulphuric acid or dilute hydrochloric acid is added to the flask.

iii. When the reaction takes place, a solution of zinc sulphate is formed and hydrogen gas is produced. The reaction is:

Zn + H₂SO₄→ ZnSO₄ + H₂

iv. The gas formed is collected in a jar by downward displacement of water.

v. Because H₂ is a gas lighter than air.