GCSE Chemistry: Paper 2 RPA

You can measure rate of reactions via a change in mass and what other method?

What best describes the apparatus for the 'disappearing cross test'?

• Stopwatch, ruler, bung, conical flask, cross

• Data logger, cross, sodium carbonate, conical flask

• Sodium thiosulfate, HCl, stopwatch, conical flask

• Sodium diosulfate, HCl, stopwatch, bung, conical flask

What is the missing piece of equipment from the measuring gas experiment?

Conical flask, magnesium, HCl, stopwatch, bung........

What is the independent variable in both RPA's?

Check each correct control variable for disappearing cross

• Time

• Concentration of HCl

• Mass and concentration of sodium thiosulfate

• Same person viewing the experiment

What piece of equipment makes the results of the experiment more accurate?

Why is a gas syringe used?

• They are cheap

• They have high resolution so usually quite accurate

• They remove chance of human error

• No gas goes to waste

In paper chromatography, what is the mobile phase?

What are the two reasons that different substances have different Rf values?

• They are more or less dilute

• They are more or less soluble

• They are more or less attracted to the paper

• They react better or worse with water

What should be used to draw the baseline?