Preparation and testing of hydrogen gas
React zinc with dilute hydrochloric acid and identify the gas with a burning splint.
Objectives
- Prepare hydrogen from a metal and a dilute acid.
- Identify hydrogen by its “pop” test.
Theory
Metals above hydrogen in the reactivity series displace hydrogen from dilute acids. Hydrogen is a colourless, odourless gas that is less dense than air and burns explosively with a squeaky pop when mixed with air.
Zn + 2HCl → ZnCl₂ + H₂↑
Procedure
- Put on your safety goggles and lab coat.
- Place a conical flask on the bench.
- Add about 5 g of zinc granules to the flask.
- Add about 40 mL of dilute hydrochloric acid.
- Watch the reaction begin.
- Test the gas with a burning splint.
Precautions
- Keep flames away from the apparatus until you test a small sample.
- Use dilute acid only.
- Subject
- Chemistry
- Grade
- 9–10
- Chapter
- Some Gases (Nepal National Curriculum (CDC), grade 9)
- Difficulty
- Easy
- Duration
- 15 min
- Safety level
- Medium
- Version
- 1.0
Apparatus
- Conical flask (250 mL)
Chemicals
- Zinc granules Zn
- Dilute hydrochloric acid HCl Corrosive
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