Chemistry Paper 1 Practicals

Question 1

Describe the process by which you make soluble salts?

Answer 1

You make soluble salts by heating the acid until it is almost boiling
Then you add the salt into the fixed volume of dilute acid
The acid will change colour
The reaction stops once all the acid is reacted
You then filter to remove any unwanted salt and evaporate the solution to obtain crystals

Question 2

Why is salt added in excess when making soluble salts?

Answer 2

Salts are added in excess as you want to react all the acid as otherwise it will contaminate the salt and become dangerously concentrated

Question 3

Describe the process by which electrolysis is used for separating

Answer 3

1. Add 50 cm cubed of solution into a beaker
2. Add petri dish on the beaker
3. Insert two electrodes (they won’t touch)
4. Attach crocodile leads to rods and connects to the power supply at 40V
5. The cathode will be coated by the metal if the metal is less reactive than hydrogen, making the electrode brown-ish
6. At the anode, bubbles will form. You can place litmus paper in the solution and if it changes colour that means there is chlorine gas present.

Question 4

Describe the practical for temperature changes

Answer 4

1. Measure 30cm cubed of acid
2. Transfer the acid to the polystyrene cup in a beaker
3. Use a thermometer to measure the temperature of acid and record it
4. Use a measuring cylinder to measure 5cm cubed of the solution and transfer to a polystyrene cup
5. Add plastic lid and place thermometer through holes
6. stir solution with the thermometer, and record the highest temperature
7. . carry out the experiment 7 times and find the mean

Question 5

What is the independent variable of the temperature change practical?

Answer 5

The independent variable of the temperature change practical is the volume of the solution

Question 6

What is the dependant variable of the temperature change practical?

Answer 6

The dependant variable of the temperature change practical is the maximum temperature reached

Question 7

What are the control variables of the temperature change practical?

Answer 7

The control variable of the temperature change practical is the volume of acid, and concentrations of acid and solutions