Question

explain how hydrogen gas is collected in laboratory​

Answer 1

Hydrogen gas is prepared in laboratory by the action of dilute HCl upon granulated zinc. ... The hydrogen gas thus formed is collected in a gas jar through delivery tube by the downward displacement of water. Purification: The hydrogen gas thus obtained may contain different impurities like H2S, NO2, CO2, moisture etc

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Answer 2

Hydrogen gas is collected in the laboratory​ by performing the experiment between dilute Hydrochloric acid (HCl) and zinc (Zn) pieces. This is demonstrated by the following chemical reaction:

Zn + 2HCL → ZnCl₂ + H₂

Materials Required for the experiment in the laboratory:

• Conical Flask
• Thistle Funnel
• Delivery Tube  
• Water Filled Container
• Test Tube

Steps followed for the experiment in the laboratory:

1. Put some zinc pieces in the conical flask.
2. Now, with the help of a thistle funnel, pour dilute hydrochloric acid into the conical flask.
3. You will observe, that zinc pieces and Hydrochloric acid will start reacting with each other which automatically starts producing hydrogen gas.
4. The Delivery tube, which is connected between the conical flask and water-filled container will help the hydrogen gas to be collected into it.
5. Put the inverted test tube inside the water-filled container and after some time you will observe that the hydrogen gas will be collected inside the inverted test tube, hydrogen being lighter than water.

Thus, hydrogen gas is collected in the test tube after the reaction between zinc and hydrochloric acid, in the laboratory.