Chemistry · May / June 2022 · Paper 61 · Question 2
0620
As printed in the paper
The question as text
A student investigated the rate at which hydrogen gas is made when magnesium reacts with two different solutions of dilute hydrochloric acid, C and D, with different concentrations. The dilute hydrochloric acid was in excess in both experiments. Two experiments were done using the apparatus shown. bung conical flask dilute hydrochloric acid clamp trough water inverted 100 cm3 measuring cylinder rubber delivery tube Experiment 1 ● A measuring cylinder was used to pour 50 cm3 of dilute hydrochloric acid C into a conical flask. ● The initial temperature of the dilute hydrochloric acid was measured using a thermometer. ● The apparatus was set up as shown in the diagram. ● The bung was removed from the conical flask and a coiled 5 cm length of magnesium ribbon was added to the flask. The bung was replaced immediately and a timer started. ● The volume of gas collected in the inverted measuring cylinder was recorded every 20 seconds fo ● The final temperature of the dilute hydrochloric acid in the flask was measured using a thermometer.
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2(a)[2]
both temperatures recorded correctly (25.0, 34.0)
all eight measuring cylinder volumes correct (27, 48, 65, 78, 86, 89, 90, 90)
2(b)[3]
both temperatures recorded correctly (25.5, 31.0)
both temperatures recorded 1 dp in (b)
all eight measuring cylinder volumes correct (12, 23, 33, 42, 50, 57, 62, 65)
2(c)[5]
y-axis scale in linear and points extend over halfway up scale
all points for Experiment 1 and 2 plotted correctly
two best fit curves
lines both extended to (0,0) and are labelled
2(d)[3]
correct working shown on graph
correct reading from their working shown on graph.
cm3
2(e)[2]
solution C is more concentrated than solution D
as reaction is faster
2(f)(i)[1]
increases
2(f)(ii)[1]
none / stays the same
2(f)(iii)[1]
use a water bath
2(g)[1]
minimise gas loss / escape
2(h)[1]
(more points / data so) better / smoother graph / curve / line
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