Rate of Reaction RPA

Question 1

Method for investigating change in concentration on rate of reaction

Answer 1

1) use measuring cylinder to add 10cm cubes of sodium thiosulfate to conical flask
2) place conical flask on white tile with large black cross on it
3) use different measuring cylinder to add 10cm cubed hydrochloric acid to the conical flask
4) swirl solution and start stopwatch
5) look down through top of conical flask and record time taken for black cross to no longer be visible (solution has turned cloudy)
6) repeat steps 1-5, each time using same volume of acid and sodium thiosulfate but lowering concentration of sodium thiosulfate
7) repeat investigation 2 more times to calculate mean time for each concentration
8) plot results on graph with time in x axis and concentration on y axis to compare rate of reaction for each concentration

Question 2

Reproducible meaning

Answer 2

Investigation can be repeated by different person using different equipment/ technique but still get the same result

Question 3

Method for investigating effect of changing concentration on rate of reaction by measuring volume of gas produced

Answer 3

1) use measuring cylinder to add 50cm cubed hydrochloric acid to conical flask
2) attach conical flask to bing and delivery tube
3) place delivery tube into a container full of water and place inverted measuring cylinder full of water over the delivery tube
4) add 3cm cubed strip of magnesium to acid in conical flask and start stopwatch
5) measure volume of gas in measuring cylinder every 10 seconds until no more gas is given off
6) repeat investigation using different concentration of hydrochloric acid
7) plot results on graph with volume of gas produced on y axis and time on x axis, drawing separate curves for each concentration