CHAPTER 21 – RATES OF REACTIONS


Past paper questions 1. Sample Paper 2018, Question 15


Some chemical reactions proceed quickly while some proceed at a slower rate. During your studies, you investigated the effect of a number of variables on the rate of production of a common gas.


a. Name a common gas that could be produced in the laboratory.


b. Draw a labelled diagram of how this gas could be produced. Include labels for any equipment and chemicals used.


c. Explain how you tested this gas to confirm its identity. Include the result of the test. A student carried out an experiment to investigate the effect of temperature on the rate of production of a certain gas. The first reaction happened at 20 °C and the second one at 30 °C. In both cases the gas produced was passed through water as it was collected. This was to ensure that the gas was always at room temperature (a constant) when its volume was measured. The student recorded the following results:


Time (s)


Volume of gas (cm3 reaction at 20 °C


7


120 150


13 17 19 20


) for


Volume of gas (cm3 reaction at 30 °C


00 0 30 60 90


10 16 19 20 20


d. Draw graphs for both sets of results. e. State two conclusions the student could have drawn from the results.


j Go to page 112 of your Assessment Book to answer more exam-style questions. ) for


Elements of Science 211


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