Tests

Question 1

Test for oxygen

Answer 1

A glowing splint relighting

Question 2

Test for carbon dioxide

Answer 2

Limewater goes milky

Question 3

Why does limewater go milky when you add carbon dioxide?

Answer 3

Carbon dioxide reacts with the calcium hydroxide forming calcium carbonate and water

Question 4

Test for chlorine

Answer 4

Will bleach damp litmus paper,

Question 5

What happens when you test for chlorine with blue litmus paper?

Answer 5

Blue litmus paper will turn red first then white - acidic gas

Question 6

Test for ammonia

Answer 6

Turns damp red litmus paper blue (alkali)

Question 7

Test for water

Answer 7

White anhydrous copper (II) sulphate turns blue

Question 8

What type of reaction is the chemical test for water

Answer 8

Reversible, very exothermic

Question 9

What is the physical test for water?

Answer 9

Boils at 100 degrees Celsius

Question 10

Test for positive ions (cations)

Answer 10

Flame test

Question 11

Describe a flame test

Answer 11

1. Clean a piece of nichrome wire by dipping it in hydrochloride acid
2. When the wire no longer gives a colour when placed in a roaring flame
3. It is then dipped into what you are testing
4. Observe colour

Question 12

What colour do calcium ions go in a flame test

Answer 12

Brick red

Question 13

What colour do potassium ions go in a flame test?

Answer 13

Lilac

Question 14

What colour do sodium ions go in a flame test

Answer 14

Orange-yellow

Question 15

What colour do lithium ions go in a flame test?

Answer 15

Red (Crimson)

Question 16

What is the test for hydroxide ions?

Answer 16

1. Add sodium hydroxide solution

2. Observe colour of precipitate

Question 17

Why does the hydroxide test work?

Answer 17

Because most metal hydroxides are insoluble in water (except group 1 metals)

Question 18

What colour does copper (II) precipitate form

Answer 18

Blue

Question 19

What colour does iron (III) precipitate form

Answer 19

Orange-brown

Question 20

What colour does iron (II) precipitate form

Answer 20

Green

Question 21

Test for carbonate ions (CO32-)

Answer 21

1. Add dilute nitric acid
2. Bubbles of gas will be observed
3. Gas can be tested with limewater (carbon dioxide)

Question 22

Test for sulphate ions (SO42-)

Answer 22

1. Add dilute hydrochloric acid
2. Add barium chloride
3. If sulphate ions are present a white precipitate is formed (barium sulphate)

Question 23

Why does the test for sulphate ions work?

Answer 23

Because barium sulphate is insoluble

Question 24

Formula for barium sulphate

Answer 24

BaSO4 (white precipitate)

Question 25

Test for halides

Answer 25

1. Add dilute nitric acid 2. Add silver nitrate solution 3. Observe colour of precipitate

Question 26

What colour do chloride ions go in the halide test

Answer 26

White

Question 27

What colour do bromide ions go in the halide test

Answer 27

Cream

Question 28

What colour do iodide ions go in the halide test

Answer 28

Yellow

Question 29

Test for hydrogen

Answer 29

Lit splint goes out with squeaky pop