Practical questions

You will complete 21 required practical activities if you are studying GCSE combined science: Trilogy. You could be asked questions about the apparatus, methods, safety precautions, results, analysis and evaluation of these experiments.

There will be a number of different types of practical based questions. Some will be on the set required practicals, some will cover the working scientifically terms and some will be on other science practicals which you might have done in class. Use all the information given in the question particularly any diagrams to help you understand what the question is about.

There is one required practical activity in the 'Rate and extent of chemical change' section:

  • Investigate how changes in concentration affect the rates of reactions by a method involving measuring the volume of a gas produced and a method involving a change in colour or turbidity.

Sample question 1 - Foundation

Question

The 'iodine clock' reaction occurs when two colourless solutions are mixed in a conical flask. After a period of time (which varies between several seconds and several minutes) the mixture turns very dark blue. A diagram of this method is shown below.

Conical flask on a cross

Why has the conical flask been placed onto a piece of white paper which has a cross drawn on it? [1 mark]

This question has been written by a Bitesize consultant as a suggestion to the type of question that may appear in an exam paper.

So that the timer can be stopped when the cross can no longer be seen when viewed from above [1]

Sample question 2 - Foundation

Question

When measuring the volume of gas produced in a reaction, one piece of apparatus that can be used is a gas syringe. Describe another way of measuring the volume of gas produced during a reaction. You may use a labelled diagram in your answer.

[2 marks]

This question has been written by a Bitesize consultant as a suggestion to the type of question that may appear in an exam paper.

Inverted (upside down) measuring cylinder [1] filled with water and placed in a water bath [1].

Sample question 3 - Higher

Question

A student investigates the rate of the reaction between sodium carbonate and hydrochloric acid using the apparatus below.

Tube through bung into test tube

Identify the error in the way the student set up the apparatus. Describe what would happen if the student used the apparatus shown. [2 marks]

This question is AQA material which is reproduced by permission of AQA.

The delivery tube has been stuck into the acid [1]

Therefore the acid would be pushed up the tube and into the water bath [1]

Sample question 4 - Higher

Question

The student corrected the error in the previous question and measured the volume of gas produced for different masses of sodium carbonate. One of the results was an anomaly. The volume of gas collected for this result was far too low. Suggest what may have happened to cause this anomaly. [1 mark]

This question is AQA material which is reproduced by permission of AQA.

Any one from:

  • bung not put in firmly
  • gas lost before bung put in
  • leak from tube

[1]