Chemical Tests

Question 0

Describe the chemical test for carbon dioxide.

Answer 0

Turns limewater cloudy when bubbled through it.

Question 1

Describe chemical tests for ammonia gas.

Answer 1

Antonia will turn moist litmus paper from red to blue as it is a alkaline gas.

Question 2

Describe the chemical test for chlorine.

Answer 2

Chlorine turns moist litmus paper from blue to red (acidic) and then bleaches it (white). It is the only gas which can do this.

Question 3

Describe the chemical test for hydrogen.

Answer 3

Place a lit splint into a test tube of hydrogen and you will hear a pop due to hydrogen being highly flammable.

Question 4

Describe the chemical test for oxygen.

Answer 4

Place a blowing splint into a test-tube of oxygen and it will relight as it supports burning.

Question 5

Describe the chemical tests for aluminium.

Answer 5

1. Add NaOH- white ppt
   Add excess NaOH- ppt dissolves
2. Add NH3(aq)- white ppt
   Add excess NH3(aq)- insoluble ppt

Question 6

Describe the chemical tests for calcium.

Answer 6

1. Add NaOH- white ppt
   Add excess NaOH- insoluble ppt
2. Add NH3(aq)- no change

Question 7

Describe the chemical tests for copper(II).

Answer 7

1. Add NaOH- light blue ppt
   Add excess NaOH- insoluble ppt
2. Add NH3(aq)- light blue ppt
   Add excess NH3(aq)- ppt dissolves (gives dark blue solution)

Question 8

Describe the chemical tests for Iron (II).

Answer 8

1. Add NaOH- green ppt
   Add excess NaOH- insoluble ppt
2. Add NH3(aq)- green ppt
   Add excess NH3(aq)- insoluble ppt

Question 9

Describe the chemical tests for Iron (III).

Answer 9

1. Add NaOH- brown ppt
   Add excess NaOH- insoluble ppt
2. Add NH3(aq)- brown ppt
   Add excess NH3(aq)- insoluble ppt

Question 10

Describe the chemical tests for Zinc.

Answer 10

1. Add NaOH- white ppt
   Add excess NaOH- ppt dissolves
2. Add NH3(aq)- white ppt
   Add excess NH3(aq)- ppt dissolves

Question 11

Describe the test for ammonium ions (NH4+).

Answer 11

1. Heat in a boiling tube to give off ammonia gas (NH3).

2. Ammonia turns damp litmus paper from red to blue (alkaline)

Question 12

Describe the test for carbonates.

Answer 12

1. Add HCl
2. Should give off CO2 gas
3. Bubble gas through limewater (turns cloudy) to test that it’s CO2.

Question 13

Describe the test for chlorides.

Answer 13

1. Add excess nitric acid and then silver nitrate.

2. Gives white ppt

Question 14

Discribe the test for iodides.

Answer 14

1. Add excess nitric acid and then silver nitrate.

2. Pale yellow ppt.

Question 15

Discribe the test for nitrates.

Answer 15

1. Heat with NaOH and a piece of aluminium foil.

2. Ammonia gas given off, so can be tested with damp litmus paper (red to blue)

Question 16

Describe the test for sulphates.

Answer 16

1. Add excess HCl and aqueous Barium Chloride (BaCl2)

2. White ppt forms.

Question 17

Describe the 2 tests for water.

Answer 17

1. Turns Cobalt(II)chloride paper Blue -> Pink

2. Turns anhydrous Copper(II)sulphate white -> blue

Question 18

Describe the test for oxidants.

Answer 18

Oxidants turn aqueous Potassium Iodide (KI) from colourless -> brown

Question 19

Describe the test for reductants.

Answer 19

Reductants turn ACIDIFIED Potassium manganate (KMnO4) from purple -> colourless

Question 20

What substance can be described as having a ‘Vinegary’ smell?

Answer 20

Carboxylic acids eg. Ethanoic acid.