Practicals (Paper 2)

Question 1

What is the method for investigating rates of reaction?

Answer 1

• Prepare 3 sets of marble chips on folded paper, one for each size of chip, make sure each set has the same mass
• Add the marble chips and a known volume of dilute hydrochloric acid to a conical flask put the flask on the balance and record the weight and also record the mass of the marble chips add these masses together, also remember to plug the flask with cotton wool
• Remove the cotton wool, add the chips to the acid and start the stopwatch
• Record the mass every 30 seconds for a few minutes, calculate the change in mass at each interval and calculate the mean change in mass
• Calculate the mean rate of reaction using the calculation: mean rate of reaction = change in mass / chosen time

Question 2

What is the method for investing combustion?

Answer 2

• Securely clamp the calorimeter
• Add a known volume of cold water to the calorimeter and record its temperature
• Measure and record the mass of a spirit lamp including its fuel and lid
• Place the spirit lamp underneath the calirometer
• Remove the lamps lid and light the wick
• Stir the water as it’s heated when the temperature has increased sufficiently, put out the flame
• Measure and record the water temperature and the spirit lamp with lid
• Empty the calirometer and repeat these steps with different alcohols
• For each alcohol, calculate the increase in temperature and the decrease in mass
• Increase in temperature / decrease in temperature to calculate the temperature increase / gram of alcohol burned