Question

Describe briefly the laboratory preparation of hydrogen gas

Answer 1

Hydrogen gas can be prepared in the laboratory through several methods, with one of the most common being the reaction of a metal with an acid. Here’s a brief outline of the process using zinc and hydrochloric acid as an example:

### Materials Needed:
- Zinc granules or zinc powder
- Dilute hydrochloric acid (HCl)
- Test tube or flask
- Delivery tube
- Water trough (for gas collection)
- Bunsen burner (optional for heating)

### Procedure:
1. **Set Up the Apparatus**: Place a small amount of zinc granules in a test tube. Connect a delivery tube to the top of the test tube, leading to an inverted water trough or gas jar to collect the hydrogen gas.

2. **Add Acid**: Carefully pour dilute hydrochloric acid into the test tube containing zinc.

3. **Observe the Reaction**: The reaction between zinc and hydrochloric acid produces hydrogen gas and zinc chloride. The chemical reaction is as follows:
\[
\text{Zn (s)} + 2 \text{HCl (aq)} \rightarrow \text{ZnCl}_2 (aq) + \text{H}_2 (g)
\]
4. **Collect the Gas**: As hydrogen gas is produced, it will rise through the delivery tube and can be collected in the inverted gas jar or water trough.

5. **Testing for Hydrogen**: To confirm the presence of hydrogen gas, you can bring a lit splint near the mouth of the gas jar. If hydrogen is present, it will produce a characteristic "pop" sound.

### Safety Precautions:
- Wear safety goggles and gloves when handling acids.
- Conduct the experiment in a well-ventilated area or under a fume hood, as the reaction can produce fumes.

This method is straightforward and effectively demonstrates the laboratory preparation of hydrogen gas.