Chemistry · Oct / Nov 2023 · Paper 61 · Question 2
0620
As printed in the paper
The question as text
Copper(II) carbonate reacts with dilute acids to make carbon dioxide gas. Malachite is a mineral that contains copper(II) carbonate. A student investigates the rate of reaction between powdered malachite and dilute ethanoic acid at different temperatures. The student does six experiments. Experiment 1 ● Use a measuring cylinder to pour 40 cm3 of dilute ethanoic acid into a conical flask. ● Warm the dilute ethanoic acid by about 5 °C. ● Measure the temperature of the acid using a thermometer. ● Set the apparatus up as shown in Fig. 2.1. trough water clamp inverted 100 cm3 measuring cylinder dilute ethanoic acid conical flask bung rubber delivery tube Fig. 2.1 ● Remove the bung from the conical flask and add 1.0 g of powdered malachite to the conical flask, replace the bung and start a stop-clock. ● Record the time taken for 100 cm3 of gas to be collected in the measuring cylinder. ● Empty the conical flask and rinse it with distilled water. Experiment 2 ● Repeat Experiment 1 but warm the dilute ethanoic acid by about 10 °C. Experiment 3 ● Repeat Experiment 1 but warm the dilute ethanoic acid by about 15 °C. Experiment 4 ● Repeat Experiment 1 but warm the dilute ethanoic acid by about 25 °C. Experiment 5 ● Repeat Experiment 1 but warm the dilute ethanoic acid by about 35 °C. Experiment 6 ● Repeat Experiment 1 but warm the dilute ethanoic acid by about 40 °C.
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2(a)[5]
M1 and M2 all temperatures correct (26.5, 31.0, 36.0, 42.0, 53.0, 59.5)
M3 all six temperatures recorded to 1 dp
M4 all times correct (282, 195, 148, 110, 65, 44)
M5 all six times in seconds only
2(b)[4]
M1 appropriate linear vertical scale so that points take up more half space
M2 and M3 all points plotted correctly
M4 a suitable best-fit curve drawn
2(c)(i)[2]
M1 2.27(272727...)
M2 cm3 / s
2(c)(ii)[1]
6
2(d)[3]
M1 suitable extrapolation to 65 °C (and beyond)
M2 working shown on graph
M3 correct reading from graph
2(e)[1]
circle round 50 cm3
2(f)(i)[1]
displaced / pushed out of flask by carbon dioxide
2(f)(ii)[1]
the volume of air displaced is the same as the volume of carbon dioxide
2(g)[2]
M1 reason: heat lost (to surroundings) / glass / flask is not a good insulator / glass / flask conducts / absorbs heat
M2 change: insulate (the flask)
or
place in water bath (kept at the starting temperature of the acid)
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