Vacuum pump adapting a balloon air pump

Materials

a) a balloon air pump (made in China)

b) a big rubber bung (NO.11)

c) glass tube (outer diameter 6 mm, length 5 cm)

Fabrication

1.  To make an attachment for the balloon air pump, make a hole of 5 mm at the centre of the rubber bung, make a hollow around the hole, and push the glass tube through the hole as shown in Fig.7.

2.    Attach the attachment to the bottom end of the balloon air pump as shown in Fig.7.

Things to do:

1.  Connect an empty plastic bottle to a vacuum pump using the attachment A.Evacuate the plastic bottle and observe what happens.

2. Before evacuating the plastic bottle, measure the total weight of the equipment using an electronic balance. After evacuating the plastic bottle, measure the total weight again. What does the difference between two measurements mean?

3. Put a little inflated balloon in a flask and connect the syringe to the flask using the plastic tube and the rubber bung. Evacuate the flask and observe what happens.

4. Put hot water about 90℃  in the flask and connect the syringe to the flask using the plastic tube and the rubber bung. Evacuate the flask and observe what happens.