ALL REQUIRED PRACTICALS

Question 1

Required Practical: How do you investigate the effect of concentration on rate of reaction using sodium thiosulfate and hydrochloric acid?

Answer 1

Mix sodium thiosulfate with HCl in a conical flask over a paper with a cross. Time how long it takes for the cross to disappear. Repeat with different concentrations.

Question 2

Required Practical: How do you measure the volume of gas produced in a reaction using magnesium and HCl?

Answer 2

React Mg with HCl in a conical flask. Collect hydrogen gas using a gas syringe. Measure gas volume at regular time intervals.

Question 3

Required Practical: Describe how to perform a flame test for metal ions.

Answer 3

Clean nichrome wire, dip in compound, place in blue Bunsen flame. Record flame colour: Li+ (crimson), Na+ (yellow), K+ (lilac), Ca2+ (orange-red), Cu2+ (green).

Question 4

Required Practical: How do you identify metal ions using sodium hydroxide?

Answer 4

Add NaOH to metal ion solutions. Observe precipitate colour: Cu2+ (blue), Fe2+ (green), Fe3+ (brown), Al3+/Ca2+/Mg2+ (white; Al3+ dissolves in excess NaOH).

Question 5

Required Practical: How do you test for carbonates, halides and sulfates?

Answer 5

Carbonates: Add HCl – fizzing (CO2). Halides: Add nitric acid + silver nitrate – white (Cl-), cream (Br-), yellow (I-) ppt. Sulfates: Add HCl + BaCl2 – white ppt.

Question 6

Required Practical: How do you separate mixtures using paper chromatography?

Answer 6

Draw a baseline. Add ink spots. Dip in solvent below line. Let solvent rise. Measure Rf = distance spot/distance solvent.

Question 7

Required Practical: How do you produce potable water from salt water?

Answer 7

Distillation: Boil salt water, condense steam. Test distillate’s boiling point (should be 100°C).

Question 8

Required Practical: How do you test and purify water samples?

Answer 8

Test pH and for dissolved solids (mass after evaporation). Filter to remove solids. Distill and re-test.