Qualitative Analysis

Question 1

What is the test for H2?

Answer 1

Use a lit splint - a ‘squeaky pop’ is heard

Question 2

What is the test for O2?

Answer 2

Use a glowing lit splint - the splint relights

Question 3

What is the test for CO2?

Answer 3

Bubble through limewater - limewater goes cloudy

Question 4

What is the test for NH3?

Answer 4

Use damp red litmus - litmus paper turns blue

Question 5

What is the test for Cl2?

Answer 5

Use damp blue litmus - litmus goes red then is bleached white

Question 6

How do you test for ammonium cation?

Answer 6

1) Add aqueous sodium hydroxide (NaOH)
2) Ammonia forms which is soluble in water
3) Warm the solution to release the ammonia gas
4) Test the gas using moist litmus paper - this will turn damp red litmus paper blue

Question 7

How do you test for a cation in solution?

Answer 7

1) Add 3 drops of sodium hydroxide (NaOH) to 3cm^3 of the solution with the cation
2) Depending on the precipitate formed, the solution goes different colours

Question 8

What precipitate is formed when you add sodium hydroxide to a solution containing copper(II) cation?

Answer 8

Blue precipitate

Question 9

What colour precipitate is formed when you add sodium hydroxide to a solution containing iron(II) cation?

Answer 9

A green precipitate

Question 10

What colour precipitate is formed when you sodium hydroxide to a solution containing iron(III) cation?

Answer 10

A brown precipitate

Question 11

What precipitate is formed when you add sodium hydroxide to a solution containing aluminium cation?

Answer 11

A white precipitate forms then dissolves

Question 12

What colour precipitate is formed when you add sodium hydroxide to a solution containing calcium cation?

Answer 12

A white precipitate

Question 13

How do you flame test a solid?

Answer 13

1) Dip a nichrome wire into concentrated hydrochloric acid
2) Dip the nichrome wire into the solid compound
3) Place in a blue Bunsen flame
4) Observe colour

Question 14

How do you flame test a liquid?

Answer 14

Put a splint soaked in the liquid and observe the colour

Question 15

What is the flame test colour for a lithium ion?

Answer 15

Red

Question 16

What is the flame test colour for a sodium ion?

Answer 16

Yellow

Question 17

What is the flame test colour for a potasium ion?

Answer 17

Lilac

Question 18

What is the flame test colour for a calcium ion?

Answer 18

Orange-red

Question 19

What is the flame test colour for a copper(II) ion?

Answer 19

Blue-green

Question 20

How do you test for Halide ions?

Answer 20

1) Add dilute nitric acid
2) Add silver nitrate solution
3) Observe colour and formed precipitate

Question 21

What colour precipitate does an iodine ion form?

Answer 21

Yellow

Question 22

What colour precipitate does an bromine ion form?

Answer 22

Cream

Question 23

What colour precipitate does an chlorine ion form?

Answer 23

White

Question 24

How do you test for sulfate ions?

Answer 24

1) Add dilute hydrochloric acid
2) Add barium chloride solution
3) White precipitate forms

Question 25

How do you test for carbonate ions?

Answer 25

1) Add dilute hyrdochloric acid
2) CO2 gas will form in the presence of carbonate ions
3) Bubble through limewater and it will go cloudy if there is CO2

Question 26

What colour does methyl orange go in acids and alkalis?

Answer 26

In alkaline it is yellow, in acids its red, orange in neutral

Question 27

What colours do Phenolphthalein go?

Answer 27

Pink in alkaline, clear in neutral and acid

Question 28

What colours is litmus paper in acid and alkali?

Answer 28

Red in acid, blue in alkali