RP3-Investigation of how the rate of reaction changes with temperature

Question 1

What is this method also known as?

Answer 1

How long it takes for the cross to disappear or measuring the effect of increasing temperature on the rate of reaction

Question 2

Describe how you would investigate the rate of reaction

Answer 2

1. Add about 10 cm of 1 moldm-3 hydrochloric acid to the ‘acid’ tube. Place this tube into a plastic container (without the cross under it).
2. Use a measuring cylinder to add 10.0 cm of 0.05 moldm-3 sodium thiosulfate solution to the second tube. Place this tube into the plastic container with the cross under it and carefully place a thermometer in this tube.
3. Record the start temperature and then add 1 cm of the acid to the thiosulfate solution and start timing.
4. Look down through the tube from above and record the time for the cross to disappear from view.
5. Record the final temperature of the reaction mixture, then pour the cloudy contents of the tube into the sodium carbonate solution.
6. Now add water from a very hot water tap (or kettle) to the plastic container. The water should be no hotter than 55 °C. Add cold water if necessary.
7. Measure another 10.0 cm of 0.05 mol dm sodium thiosulfate solution into a clean tube. Insert this tube into the correct hole in the plastic container (ie the one with the cross under it).
8. Leave the tube to warm up for about 3 minutes.
9. Repeat steps (3) to (6) in order to obtain results for at least 5 different temperatures in total.

Question 3

What are the control volumes?

Answer 3

• same volume of sodium thiosulphate, every time
• Same volume of acid each time
• same cross
• Same thermometer
• same stopwatch
• same concentration of acid and thiosulphate

Question 4

What is the independent variables and the dependent variable?

Answer 4

Independent variable - temperature of sodium thiosulphate
dependent variable - time taken for the cross to disappear

Question 5

What does this reaction tell us?

Answer 5

The higher the temperature the higher the rate

Question 6

What are some safety tips we must be aware of?

Answer 6

• to minimise the escape of toxic sulphur dioxide gas, lid is advised
• Or perform in a fume cupboard
• once colour of the solution has changed, the sodium carbonate has been used up and the stop bath will need to be replenished

Question 7

further analysis of the results?

Answer 7

• at different temperatures the concentration of all reactants remain the same
  -the time taken to produce the same amount of sulphur at different temperatures is an indication of the rate of reaction

Question 8

Describe how a graph can be plotted?

Answer 8

• A graph can be plotted with the arrhenius equation
• Look on physics and maths tutor for the analysis

Question 9

Finished