Saturday, 5 March 2011


Let us get some basic stuff together and make a hydrogen balloon to demonstrate in the class. The main idea is to collect hydrogen gas from an acid-metal reaction and show the students the safest way to do it.

You need:

2M sulphuric acid
zinc granules
two pieces of rubber balloons
conical flask.

We will use the 2M sulphuric acid because the higher the concentration, the faster the reaction and the more gas we can collect. Just be very careful about the corrosive nature of the acid, it can cause skin irritation or burns. Use rubber hand gloves if available.

  1. Put a spoonful of zinc granules into the conical flask.
  2. Slowly pour 50ml of 2M sulphuric acid in it. The reaction takes place immediately.
  3. Use the rubber balloon to collect the gas as shown in the picture below.
  4. If you have collected enough hydrogen, take the balloon off and tie its end properly.
  5. You can collect more gas as long as the reaction is going on.

To test the hydrogen balloon, you need an iron stand and clamp to hold it. Prepare a stick at least one meter long and attach/tape a wooden splint on one end. Light the splint and put it under the balloon. It would burst out with a considerable bang.

Warning: Please ask the kids to stay away while you pop up the balloon and remind them to cover their ears.

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