Chem Tests

Question 1

Flame Test

Answer 1

Identify metal ions

Lithium (Li+) - Crimson
Potassium (K+) - Lilac
Calcium (Ca2+) - orange-red
Copper (Cu2+) - Green
Sodium (Na+) - Yellow

Question 2

Flame Test Practical

Answer 2

1. Cleaning a nichrome wire loop by submerging it in dilute hydrochloric acid
2. Dip wire loop into the sample to be tested
3. Wire loop is held in the blue flame of a Bunsen and colour is recorded

Question 3

Hydroxide precipitate tests

Answer 3

Identify metal ions using sodium hydroxide (NaOH)

Iron(II) ions (Fe2+) - Green

Iron(III) ions (Fe3+) - Orange-brown

Copper(II) ions (Cu2+) - blue

Calcium ions (Ca2+) - White precipitate 
of calcium hydroxide

Zinc ions (Zn2+) - White precipitate
of zinc hydroxide

In excess NaOH zinc hydroxide dissolves to form a colourless solution
Calcium hydroxide does not

Question 4

Carbonate ions

Answer 4

Compounds that contain CO3^2-) ions and react with dilute acids to form a salt, CO2 and H20

E.G: Calcium carbonate + NaOH -> Calcium chloride + CO2 + H20

• Add a few drops of dilute HCl
• If carbonate ions are present, bubbles of gas produced. It’s CO2.

You can confirm by using limewater

Question 5

Carbon Dioxide

Answer 5

Bubble the gas through lime water
If CO2 present, limewater turns cloudy

Limewater = calcium hydroxide solution

Calcium hydroxide + CO2 -> H20 and a solid white precipitate of calcium carbonate

The calcium carbonate is what turns it cloudy

Question 6

Halide ions (anions)

Answer 6

Negatively charged ions (anions)

1. Add dilute nitric acid to remove any carbonate ions
2. Silver nitrate then added. If halide ions are present, they will form a precipitate with the silver ins

Question 7

Halide ions

Answer 7

Chlorine - Silver chloride - White
Bromine - Silver bromide - Cream
Iodine - Silver iodide - Yellow

Question 8

Sulfate ions

Answer 8

Compounds that contain SO4^2- ions

1. HCl added to remove carbonate ions
2. Barium chloride is then added

If sulfates present, a white precipitate of barium sulfate will form

Question 9

Chlorine

Answer 9

1. Dampen blue litmus paper
2. Hold paper near a container that holds substance
3. If chlorine present, the paper turns red then white

Chlorine dissolves in water to form an acidic solution
Acidic, hence why it turns red

Chlorine also bleaches dyes
Hence why it turns white, it bleaches is

Question 10

Hydrogen

Answer 10

Lighted splint in container of gas

If hydrogen is present, it should ignite with a squeaky pop

Question 11

Oxygen

Answer 11

Glowing splint in container of gas

If O2 present, splint should relight