Section 2 - Pgs 43

Question 1

Describe a test for chlorine.

Answer 1

Chlorine bleaches damp litmus paper.

It may turn red for a moment because a solution of chlorine is acidic.

Question 2

Describe a test for oxygen.

Answer 2

Relights a glowing splint.

Question 3

Describe a test for carbon dioxide.

Answer 3

Turns limewater cloudy (when it is bubbled through the limewater).

Question 4

Describe a test for hydrogen.

Answer 4

Makes a squeaky pop with a lighted splint.

The noise comes from the hydrogen and oxygen forming H2O.

Question 5

Describe a test for ammonia.

Answer 5

Ammonia turns damp red litmus paper blue.

It also has a strong smell.

Question 6

Describe the test for water.

Answer 6

Water turns anhydrous copper(II) sulphate powder from white to blue (hydrated copper sulphate).

Question 7

Describe IN DETAIL the preparation and test for water.

Answer 7

Preparation:
1) Get some copper(II) sulphate, which forms blue crystals when bound to water.
2) Heat the blue hydrated copper(II) sulphate to remove water.
3) This leaves a white anhydrous copper(II) sulphate powder, with no water bound to it.
Test:
1) Add some of the substance to the White anhydrous powder.
2) If water is present, the white powder turns blue. If it isn’t, there is no change.

Question 8

What does pure mean in terms of a sample?

Answer 8

That the sample only contains one substance.

Question 9

How can you test whether a sample is pure?

Answer 9

It has set defined physical properties, like boiling point and freezing point.
E.g. Pure water always boils at 100C and freezes at 0C.