Chemistry 5070/42 — May/June 2018
Cambridge O-Level · Alternative to Practical · worked solutions for every part, with the mark scheme
Topics Experimental Contexts · Analysis, Conclusions and Evaluation · Observations and Measurements · Use of Techniques, Apparatus and Materials · Qualitative Analysis · Planning Experiments and Investigations
A student investigates two fuels: hexane and octane.
The student burns the fuels using the apparatus shown. A fixed volume of water is heated for five minutes in each experiment.
The diagrams show parts of the thermometer stem with the initial and final temperatures.
Read the initial and final temperatures from the thermometer stems and record them in the table.
Complete the table by calculating the temperature changes.
| fuel | initial temperature / | final temperature / | temperature change / |
|---|---|---|---|
| hexane | |||
| octane |
The student compares the temperature changes from the experiment with correct values found in a data book.
The student’s experimental values are lower than the correct values.
Suggest a reason, other than student error, to explain why they are lower.
______
Look at the data in the table in (a).
Which fuel releases more energy in the investigation?
Explain your answer.
fuel = ______
explanation = ______
What conclusion can be made from the temperature changes about the type of reaction that occurs?
______
The rest of this paper
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