A student investigates the rate of reaction between marble chips and hydrochloric acid - OCR Gateway - GCSE Chemistry Combined Science - Question 11 - 2018 - Paper 1
Question 11
A student investigates the rate of reaction between marble chips and hydrochloric acid.
Both experiments use 50 cm³ of hydrochloric acid and an excess of marble ch... show full transcript
Worked Solution & Example Answer:A student investigates the rate of reaction between marble chips and hydrochloric acid - OCR Gateway - GCSE Chemistry Combined Science - Question 11 - 2018 - Paper 1
Step 1
a) 6 points plotted correctly
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Answer
To correctly plot the data points for the large and small marble chips, we mark the time on the x-axis (from 0 to 24 minutes) and the total mass of carbon dioxide given off on the y-axis (from 0 to 2.0 g). The points for each time interval (0, 4, 8, 12, 16, 20, and 24 minutes) should be accurately plotted based on the provided values. A maximum of 6 points are relevant for each type of marble chip.
Step 2
b) 20 (minutes)
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Answer
The maximum collection time for the data shown is 24 minutes, but the relevant observation for the reaction using large marble chips indicates that significant mass increase reaches a plateau around 20 minutes.
Step 3
c) 1.45 g (or between 1.4 and 1.5 g)
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Answer
The total mass of carbon dioxide produced by the large marble chips at the 16-minute mark approaches 1.5 g; by extrapolating, the mass at 20 minutes can reasonably be inferred to be approximately 1.45 g.
Step 4
d) idea that slope or gradient of line for small chips (is twice as steep)
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Answer
The graph for small marble chips shows a steeper slope compared to large marble chips. The reaction with small chips occurs at a faster rate because they have a larger surface area relative to their volume, thus allowing for greater interaction with hydrochloric acid.
Step 5
e) same quantity (50 cm³) of hydrochloric acid was used in both
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Both experiments used the same initial volume of hydrochloric acid (50 cm³), ensuring consistent conditions for both tests.
Step 6
f) any one from: measuring syringe
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Answer
Apparatus such as a measuring cylinder or a syringe could have been used to accurately measure the volume of hydrochloric acid needed for the experiments.
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