Chemical Tests

Question 1

Define Cation

Answer 1

Positive

Question 2

Define anion

Answer 2

Negatives

Question 3

What colour flame does Li+ create

Answer 3

Red

Question 4

What colour flame does Ca+2 create

Answer 4

Orange

Question 5

What colour flame does Na+ create

Answer 5

Yellow

Question 6

What colour flame does Cu+2 create

Answer 6

Green

Question 7

What colour flame does K+ create

Answer 7

Lilac

Question 8

Describe a flame test

Answer 8

• dip nichrome wire into hydrochloric acid (to clean it so we can only see the colour of the sample and so the sample sticks to it)
• dip wire into sample
• place wire into blue Bunsen burner flame

Question 9

Test for hydrogen

Answer 9

Lit splint in gas goes out with a squeaky pop
Because hydrogen and oxygen react to create water, and it creates a squeaky pop as the gas is forced out of the containter

Question 10

Test for oxygen

Answer 10

Glowing splint in gas relights
Because the oxygen, splint and heat create fire

Question 11

Chemical test for water

Answer 11

Add to white anhydrous copper sulphate turns blue (hydrated copper sulphate)

Question 12

Test for water (purity test)

Answer 12

Boil - it should boil at 100 degrees not over a range of temperatures

Question 13

Test for carbon dioxide

Answer 13

Bubbled through limewater turns cloudy

Question 14

Test for chlorine

Answer 14

Damp (chlorine can diffuse into it) litmus paper in gas is bleached white

Question 15

Test for ammonia

Answer 15

Damp red litmus paper turns blue
Because OH- is produced (alkaline/base)

Question 16

Describe a hydroxide test

Answer 16

Dissolve sample in distilled water
Add sample to test tube
Add NaOH to tube

Question 17

Hydroxide tests
What colour precipitate does Cu +2 form

Answer 17

Blue

Question 18

Hydroxide tests
What colour precipitate does Fe +2 form

Answer 18

Green

Question 19

Hydroxide tests
What colour precipitate does Fe +3 form

Answer 19

Brown

Question 20

Describe a halide test

Answer 20

• dissolve sample into distilled water if solid
• add few drops of sample to test tube
• add nitric acid (HNO3)
• add few drops of silver nitrate

Question 21

Halide tests
What precipitate is formed from Chloride

Answer 21

White

Question 22

Halide tests
What precipitate is formed from bromide

Answer 22

Cream

Question 23

Halide tests
What precipitate is formed from iodide

Answer 23

Yellow

Question 24

Test for carbonate (CO3 -2)

Answer 24

Add hydrochloric acid
Fizzing = bubble gas through limewater which should turn cloudy if carbonate is present

Question 25

Test for Sulphate (SO4 -2)

Answer 25

Add hydrochloric acid No fizzing = add Barium Chloride (BaCl2) = white precipitate formed

Question 26

Which anion test is used to test for I2, Cl2, Br2

Answer 26

Halide tests Dissolve sample in distilled water if solid Add sample and nitric acid to test tube Add silver nitrate Observe colour of precipitate formed

Question 27

What cation test is used to test for Cu +2, Fe +2, Fe +3?

Answer 27

Hydroxide test Dissolve sample in distilled water if it’s a solid Add sample to test tube Add NaOH and observe

Question 28

What cation test is used to test for: Li +1 Na +1 K +1 Ca +2 Cu +2

Answer 28

Flame tests Dip nichrome wire in hydrochloric acid Dip wire into solid Place wire into blue Bunsen burner flame and observe colour