Key Practicals Part 1

Question 1

What is the method for preparing Copper(II) sulfate crystals?

Answer 1

1. Warm sulfuric acid in a beaker (do not boil).
2. Add small amounts of copper(II) oxide to the acid and stir.
3. Continue adding until no more copper(II) oxide dissolves.
4. Filter the mixture to remove unreacted oxide.
5. Heat the filtrate gently to evaporate water, allowing crystals to form.

Question 2

What are the observations when preparing Copper(II) sulfate?

Answer 2

Blue crystals form upon cooling. Unreacted black copper(II) oxide is removed during filtration.

Question 3

What is the conclusion of the Copper(II) sulfate preparation?

Answer 3

Copper(II) sulfate (CuSO₄) forms because the acid reacts with the base in a neutralization reaction:

H₂SO₄ + CuO → CuSO₄ + H₂O

Question 4

What is the method for investigating the rate of reaction using marble chips?

Answer 4

1. Add marble chips (calcium carbonate) to a conical flask containing hydrochloric acid.
2. Use a gas syringe or inverted measuring cylinder to collect the carbon dioxide gas released.
3. Measure the volume of gas produced at regular time intervals.
4. Repeat using different concentrations of hydrochloric acid.

Question 5

What are the observations when investigating the rate of reaction with marble chips?

Answer 5

Reaction occurs faster with higher acid concentration. More vigorous bubbling indicates faster carbon dioxide release.

Question 6

What is the conclusion of the rate of reaction investigation?

Answer 6

Increasing concentration increases the rate of reaction because there are more frequent collisions between reactant particles.

CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

Question 7

What is the test for hydrogen gas?

Answer 7

Insert a lit splint into a test tube containing hydrogen gas.
Positive result: A pop sound is heard.

Question 8

What is the test for oxygen gas?

Answer 8

Insert a glowing splint into a test tube containing oxygen.
Positive result: The splint relights.

Question 9

What is the test for carbon dioxide gas?

Answer 9

Bubble the gas through limewater (calcium hydroxide solution).
Positive result: Limewater turns cloudy.

Question 10

What is the test for chlorine gas?

Answer 10

Hold damp blue litmus paper over the gas.
Positive result: The paper turns red, then bleaches white.