Sharon Endebak

Hydrogen Balloon

Science Concept:

When zinc and hydrochloric acid combine, they form the gas, hydrogen.

Materials:

balloon

250 mL flask with rubber tubing on side arm and rubber stopper

yard stick with string tied to it

20 grams of zinc (mesh, NOT powder)

40 mL of dilute hydrochloric acid (6 M)

lighter

light stick

safety goggles

Directions:

1. Attach balloon to rubber arm of flask.

2. Pour the dilute hydrochloric acid into the flask, being careful not to get it on the hole in the side. Pour down the back side of the flask away from the side arm.

3. Pour in the zinc, and quickly place the rubber stopper in it, holding onto both the top and the balloon as it begins to inflate.

4. After the reaction has ceased, tie the balloon and clip it to the end of the yardstick.

5. Light the candle on the light stick and have a partner hold it for you.

6. Both you and your partner standing far away, hold the flame under the balloon.

Introduction:

Have any of you ever had to blow up balloons for a party? Well, today I am going to show you how we can blow up a balloon without using your own breath at all.

Explanation:

When the zinc and hydrochloric acid are combined, they form hydrogen gas. The gas molecules collide with the walls of the balloon, causing pressure, which causes the balloon to inflate. Hydrogen gas is also extremely flammable, and when the flame is held up to the balloon, it causes that intense explosion from the reaction with oxygen in the air.

Zn + HCl Þ H2 + ZnCl2

H2 + O2 Þ H2O + heat energy

Safety:

Be sure that each partner wears safety goggles because hydrochloric acid may spray from the balloon.

Reference:

Science Demonstrations, Elmhurst College, 2000