rates of reaction

Question 1

3:14 (Triple only) draw and explain reaction profile diagrams showing ΔH and activation energy

Answer 1

The activation energy is the minimum amount of energy required to start the reaction.

The difference between energy levels is ΔH

exothermic reaction:
- the products have less energy than the reactants
- more energy is released when bonds are formed than taken in when bonds are broken

endothermic reaction:
- the products have more energy than the reactants
- more energy is taken in to break bonds than is released when new bonds are formed

Question 2

3:16 practical: investigate the effect of different solids on the catalytic decomposition of hydrogen peroxide solution

Answer 2

• Add hydrogen peroxide into a conical flask
• Use a delivery tube to connect this flask to a measuring cylinder upside down in water trough
• Add the chosen catalyst into the conical flask and close the bung
• Measure the volume of gas produced in a fixed time using the measuring cylinder
• Repeat experiment with different catalysts and compare results

possible catalysts:
- Manganese dioxide
- Liver
- Potato
- Potassium iodide
- Copper oxide
- Sodium chloride