Rate of Reaction Experiments

Question 1

experiment to measure how surface area affects rate of reaction

Answer 1

1. set up the apparatus using marble chips and hydrochloric acid
2. measure the volume of gas produced using a gas syringe - take readings at regular time intervals and record the results in a table
3. plot a graph of results - time on the x-axis and volume on the y-axis
4. repeat the experiment with exactly the same volume and concentration of acid, and exactly the same mass of marble chips but with the marble in smaller pieces
5. then repeat with the same mass of powdered chalk

Question 2

experiment to measure how reaction rate is affected by temperature

Answer 2

1. sodium thiosulfate and hydrochloric acid are both clear solutions - they react together to form a yellow precipitate of sulfur
2. you can measure the rate by watching a black mark disappear through the cloudy sulfur and timing how long it takes to go
3. the reaction can be repeated for solutions at different temperatures - the best way to do this is to use a water bath to heat both solutions to the right temperature before you mix them
4. the depth of liquid must be kept the same each time
5. the results will show the higher the temperature the quicker the reaction and therefore the less time it takes for the mark to disappear
   NOTE: this reaction can also be used to test the effects of concentration

Question 3

experiment to measure how using catalysts affects rate

Answer 3

the decomposition of hydrogen peroxide:
2H2O2 (aq) -> 2H2O (l) + O2 (g)

1. this reaction is normally quite slow but manganese(IV) oxide (MnO2) catalyst speeds it up
2. oxygen gas is given off, which provides an ideal way to measure the rate of reaction using the gas syringe method
3. set up the apparatus and add some manganese(IV) oxide to the hydrogen peroxide
4. measure the volume of gas produced at regular time intervals - record the results in a table
5. repeat the experiment with exactly the same volume and concentration of hydrogen peroxide, but using a different catalyst (the amount of catalyst must be kept the same though)
6. you can then draw a graph with time on the x-axis and volume on the y-axis
   NOTE: this reaction can be used to measure the effects of temperature or concentration on the hydrogen peroxide solution