Chemical Tests

Question 1

Describe a method for carrying out a flame test

Answer 1

• clean platinum wire by dipping in hydrochloric acid and then into flame
• dip wire into metal salt
• place in flame

Question 2

How would you test for the ammonium ion, NH4+?

Answer 2

• add sodium hydroxide
• test the gas produced(ammonia NH3) with DAMP red litmus paper
• litmus paper will turn blue

Question 3

Flame colour

Answer 3

Li+ red
Ma+ Orange
K+ lilac
Ca2+ brick red

Question 4

Colour of precipitate when sodium hydroxide is added

Answer 4

Cu2+ blue
Fe2+ green
Fe3+ rust brown

Question 5

Colour of precipitate with dilute nitric acid & silver nitrate solution

Answer 5

Cl- white
Br- cream
I- yellow

Question 6

Ionic equations for the reactions

Answer 6

Cl- is Ag(aq) + Cl-(aq) ➡️ AgCl(s)

Br- is Ag+(aq) + Br- (aq) ➡️AgBr(s)

I- is Ag+(aq) + I-(aq)➡️ AgI(s)

Question 7

Describe a test for the sulphate anion (SO4 2-)

Answer 7

Add hydrochloride acid
Add a solution of barium chloride
White precipitate (solid) produced is barium sulphate (BaSo4)

Question 8

Describe a test for the carbonate anion (CO3 2-)

Answer 8

Add hydrochloric acid
Bubble the gas (CO2) produced through limewater
Turns cloudy

Question 9

Give a chemical test for water, H2O

Answer 9

Anhydrous copper (II) sulphate: white to blue 
Anhydrous cobalt (II) chloride: blue to pink

Question 10

Hydrogen, H2

Answer 10

Chemical test
LIGHTED SPLINT
result
SQUEAKY POP

Question 11

Oxygen, O2

Answer 11

Chemical test
GLOWING SPLINT
result
RELIGHTS

Question 12

Carbon dioxide, CO2

Answer 12

chemical test
LIMEWATER
result
TURNS CLOUDY/MILKY

Question 13

Ammonia, NH3

Answer 13

Chemical test
DAMP RED LITMUS PAPER
Result
TURNS BLUE

Question 14

Chlorine, Cl2

Answer 14

chemical test
DAMP LITMUS PAPER
result
BLEACHES/TURNS WHITE