Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Acid–alkali indicators
19 practice questions
Practice questions
1–8 of 8 · Easy
Question 1
1 mark · Easy
Answer and see the solution →State the pH value that classifies a solution as neutral.
Question 2
3 marks · Easy
Answer and see the solution →A student is given a solution and asked to measure its pH using universal indicator.
(a)[2 marks]Describe how the student should use universal indicator solution to estimate the pH of the solution.
(b)[1 mark]Explain how the student can decide on the pH value after adding the indicator.
Question 3
2 marks · Easy
Answer and see the solution →Table 1 shows the colour changes of three common indicators in different solutions.
Table 1: Indicator colours in acid and alkali Indicator Colour in Acid Colour in Alkali Litmus red ? Methyl orange red yellow Phenolphthalein ? pink (a)[2 marks]Complete the table by giving the colour of litmus in alkali and phenolphthalein in acid.
Question 4
2 marks · Easy
Answer and see the solution →Explain why a solution with pH 11 is classified as strongly alkaline rather than weakly alkaline.
Question 5
3 marks · Easy
Answer and see the solution →A student uses universal indicator solution to test three unknown liquids. The results are recorded in Table 2.
Table 2: Universal indicator results Liquid Colour observed A orange B green C purple (a)[1 mark]State the likely pH of liquid B, based on the observed colour.
(b)[1 mark]Suggest the type of solution for liquid C (strong acid, weak acid, neutral, weak alkali, strong alkali).
(c)[1 mark]Describe how the universal indicator is used to obtain this information from the liquids.
Question 6
1 mark · Easy
Answer and see the solution →What colour does methyl orange turn in an alkaline solution?
Question 7
3 marks · Easy
Answer and see the solution →The table shows five solutions and their pH values.
Table 3: Solutions and their pH values Solution pH P 3 Q 6 R 7 S 9 T 13 (a)[1 mark]Identify which solution is neutral.
(b)[1 mark]State which solution is a weak acid.
(c)[1 mark]Which solution is strongly alkaline? Explain your answer.
Question 8
2 marks · Easy
Answer and see the solution →A universal indicator chart is shown below.
Universal Indicator Colours pH Colour 2 red 5 orange 7 green 10 blue 13 purple A student tests a solution and sees that it turns orange with universal indicator.
(a)[1 mark]Estimate the pH of the solution based on the chart.
(b)[1 mark]Classify the solution as strongly acidic, weakly acidic, neutral, weakly alkaline, or strongly alkaline.