Chemical testing paper 2

Question 1

test for hydrogen gas

Answer 1

Test: use a lit splint
Result: burns with a squeaky pop

Question 2

test for carbon dioxide

Answer 2

Test: bubble through limewater
Result: limewater turns cloud

Question 3

test for oxygen

Answer 3

Use a glowing splint

Glowing splint relights

Question 4

test for ammonia gas

Answer 4

Use red litmus paper

Turns damp red litmus paper blue

Question 5

test for chlorine gas

Answer 5

Use moist litmus paper

Turns moist litmus paper white (bleaches)

Question 6

how to carry out a flame test

Answer 6

A platinum or nichrome wire is dipped into concentrated hydrochloric acid to remove any impurities.
The wire is dipped into the salt being tested so some salt sticks to the end.
The wire and salt are held in a roaring bunsen burner flame.
The colour is observed.

Question 7

lithium flame colour

Answer 7

red

Question 8

sodium flame colour

Answer 8

yellow

Question 9

potassium flame colour

Answer 9

lilac

Question 10

calcium flame colour

Answer 10

Orange- red

Question 11

copper II flame colour

Answer 11

blue - green

Question 12

Tests for NH4 + (ammonium)

Answer 12

add sodium hydroxide solution and warm

damp red litmus paper will turn blue ( ammonia gas)

Question 13

Tests for Cu2+, Fe2+ and Fe3+

Answer 13

Add sodium hydroxide and observe the colour

blue precipitate of copper hydroxide
green precipitate of iron II hydroxide
brown precipitate of iron III hydroxide

Question 14

Tests for anions Cl–, Br– and I–

Answer 14

Add nitric acid to remove impurities
Add silver nitrate solution

Chloride - white precipitate
Bromide - cream precipitate
Iodide - yellow precipitate

Question 15

Tests for sulfate anions SO4 2–

Answer 15

Add hydrochloric acid to remove impurities
Add barium chloride solution
White precipitate should form if sulfate ions are present

Question 16

Tests for carbonate ions CO3 2-

Answer 16

Add hydrochloric acid

If carbonate ions are present, fizzing will occur

Question 17

Test for the presence of water using anhydrous copper(II) sulfate

Answer 17

Add anhydrous copper (II) sulfate (CuSO4) to a sample.

If water is present the anhydrous copper (II) sulfate will change from white to blue.

Question 18

Physical test to show whether a sample of water is pure

Answer 18

If the sample is pure water it will boil at 100oC