Edexcel IGCSE Chemistry Analysis Communication and Evaluation Questions

Practise Edexcel IGCSE Chemistry data analysis, communication and evaluation by spotting anomalies, drawing curves and judging method accuracy.

Exam points

Identify anomalous results and draw conclusions from observations or plotted data.
Draw a curve of best fit through plotted practical results, including curves that level off.
Explain accuracy or validity issues such as gas loss, timing errors or uneven temperature.

Covered syllabus points

Analyse data and draw conclusions Communicate experimental findings Assess experimental reliability Evaluate accuracy and validity

[Maximum number: 2]

A student investigates the effect of temperature on the rate of reaction between two solutions, A and B . When the reaction occurs, the mixture turns from colourless to blue.

This is the student's method.
- pour $25 \mathrm{~cm}^{3}$ of solution A into a conical flask
- add solution B and measure the temperature of the mixture
- record the time taken for the mixture to turn blue

The student repeats this method at different temperatures.

(a)

The table shows the student's results.

Table for Question (a) — Edexcel IGCSE Chemistry

[ 2 ]

(i)

Draw a circle around the anomalous result.

[ 1 ]

anomalous point at $25^{\circ} \mathrm{C}$ circled

ALLOW ecf from
incorrect plotting

(ii)

Give a reason for the anomalous result.

[ 1 ]

Any one from

M1 temperature was higher than $25^{\circ} \mathrm{C}$

M2 started the timer too late / stopped the timer too early/took reading too early

ALLOW ecf from
incorrect anomalous
result circled so

[Maximum number: 1]

A student uses this apparatus to investigate the decomposition of hydrogen peroxide solution.

Figure for Question 2 — Edexcel IGCSE Chemistry

This is the equation for the reaction.

2 \mathrm{H}_{2} \mathrm{O}_{2} \rightarrow 2 \mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{2}

The student measures the volume of oxygen collected at regular intervals until the reaction stops.

The table shows the student's results.

Table for Question 2 — Edexcel IGCSE Chemistry

Draw a curve of best fit.

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Covered syllabus points

Question 1

Question (a)

Question (i)

Question (ii)

Question 2