Acid–alkali indicators
2 marks · HardDescribe how you would use universal indicator paper to measure the pH of a solution as accurately as the method allows.
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Dip the universal indicator paper into the solution, then compare the colour it turns to a pH colour chart to estimate the pH as closely as possible.
Also accept: Place a drop of the solution onto the universal indicator paper, then match the resulting colour to a pH chart.; Use a glass rod to put a drop of the solution onto the indicator paper and compare the colour with a chart.
Common mistakes: Describing use of a pH meter instead; Not mentioning comparison to pH chart
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Marking points
M1 · 1 mark · Universal indicator paper is added to/dipped into the solution (or solution added to paper).
M2 · 1 mark · Compare the colour change to a pH colour chart to estimate the pH.
Worked solution
Dip the universal indicator paper into the solution. The paper will change colour. Compare the colour to the pH colour chart to estimate the solution's pH as accurately as possible.