Chemistry AQA GCSE Paper 2 required practicals

Why should you use pencil instead of ink for the start line in chromatography?

• Pen will dissolve/smudge with the other substances in the solvent

• Pencil is clearer

• Pen will smudge easily

What is the equation for rate of reaction?

• rate of reaction= time / amount of reactant used or formed

• rate of reaction= amount of reactant used or formed x time

• Rate of reaction=amount of reactant used or formed / time

Why must temperature be controlled when investigation effect of concentration on rate of reaction?

• Particles have less energy so they move slower so there are less frequent collisions which decreases rate of reaction

• Particles have more energy so they move faster so there are more frequent collisions which increases rate of reaction

• Particles move faster so the rate of reaction increases

What safety precautions should you take for flame tests?

• No safety precautions needed

• Safety goggles and hair tied back

• Gloves

Identify the control variables of concentration effect on rate of reaction

• Volume of acid and sodium thiosulfate solution

• concentration of acid

• stopwatch time intervals

• Amount of Magnesium ribbon

What is the dependent variable?

• What you will measure

• What you will keep the same

• What you will change

Why could the rate of reaction and concentration experiment be unreliable? (disappearing cross)

• bad judgement

• Dirty goggles

• Results are subjective (based on opinion)

What does reliability mean?

• degree to which results are similar

• degree to which an experiment produces stable and consistent results

• degree to which results are the same

what does accuracy mean?

• the closeness of a measured value to a standard or known value (free from error or defect)

• how similar results are

• if the results are repeatable

Describe the relationship between the variables

• directly proportional

• proportional

• linear

• positive correlation