10 - Chemical Analysis

Question 1

How would you test for oxygen?

Answer 1

Relights a glowing splint

Question 2

How would you test for carbon dioxide?

Answer 2

Turns lime water cloudy

Question 3

How would you test for ammonia?

Answer 3

Damp red litmus paper will turn blue (heat the test solution to get ammonia gas)

Question 4

How would you test for hydrogen?

Answer 4

Squeaky pop when a lighted splint is placed into a test tube with hydrogen

Question 5

How would you test for chlorine?

Answer 5

If you put a damp blue litmus paper into a test tube with chlorine, it will bleach the damp blue litmus paper.

Question 6

How would you carry out a flame test?

Answer 6

1. Heat up a nichrome wire on the edge of a roaring blue flame.
2. Let it cool down slightly.
3. Dip it into HCl and then into the salt to be tested.
4. Put this back on the edge of the roaring blue flame and observe the colour.

Question 7

What is the colour of flame of Lithium?

Answer 7

red

Question 8

What is the colour of flame of sodium?

Answer 8

yellow

Question 9

What is the colour of flame of potassium?

Answer 9

lilac

Question 10

What is the colour of flame of calcium?

Answer 10

orange-red

Question 11

What is the colour of flame of copper?

Answer 11

blue-green

Question 12

How would you test for cations?

Answer 12

1. Dissolve salt into distilled water
2. Add a few drops of sodium hydroxide
3. Observe the colour of the precipitate

Question 13

What is the colour of precipitate of copper?

Answer 13

blue

Question 14

What is the colour of precipitate of calcium?

Answer 14

white, no change in excess sodium hydroxide

Question 15

What is the colour of precipitate of aluminium?

Answer 15

white, redissolves in excess sodium hydroxide

Question 16

What is the colour of precipitate of ammonium?

Answer 16

no precipitate

Question 17

What is the colour of precipitate of iron(II)?

Answer 17

green

Question 18

What is the colour of precipitate of iron(III)?

Answer 18

brown

Question 19

What are cations?

Answer 19

• positive

- metals

Question 20

What are anions?

Answer 20

• negative

- non metal

Question 21

How would you test for halides?

Answer 21

1. place a 1cm depth of potassium chloride, potassium bromide and potassium iodide in seperate test tubes
2. add 1cm depth of nitric acid to each test tube
3. add a few drops of cm depth of silver nitrate
4. note the colour change

Question 22

Why would you not want to use a lot of silver nitrate?

Answer 22

This solution contains silver, silver is expensive, not waste money

Question 23

What is the colour of precipitate of chloride?

Answer 23

white

Question 24

What is the colour of precipitate of bromide?

Answer 24

cream

Question 25

What is the colour of precipitate of iodide?

Answer 25

yellow