1 . Blowing Up Balloons with CO₂

Chemical reactions (化学反应) make for some great experiments. You can make use of the CO₂(carbon dioxide) given off by a baking soda (小苏打) and lemon juice reaction to blow up your balloon!

What you’ll need:

●Balloon        ●About 40ml of water        ●Soft drink bottle

●Juice from a lemon          ●I teaspoon of baking soda

Instructions:

●Before you begin, make sure that you pull the balloon long to make it as easy as possible to blow up.

●Put the 40ml of water into the soft drink bottle.

●Add the baking soda and mix it with water.

●Put the lemon juice in and quickly put the balloon over the mouth of the bottle.

What’s happening?

If all goes well, then your balloon should inflate! Adding the lemon juice to the baking soda creates a chemical reaction and produces CO₂. The gas rises up and escapes (逸出) through the soft drink bottle. It doesn’t, however, escape the balloon, pushing it outwards and blowing it up.

1. Which of the following do you need for the experiment?

A．Two cups.	B．Apple juice.
C．250 ml water.	D．A teaspoon of baking soda.

2. What should you do before the experiment?

A．Heat the water.	B．Drink some juice.
C．Blow up the balloon.	D．Pull the balloon long.

3. What is the purpose of the text?

A．To describe an experiment.	B．To introduce a game.
C．To produce soft drinks.	D．To save some chemicals.