Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Acid–alkali indicators
19 practice questions
Practice questions
11–19 of 19
Question 11
3 marks · Normal
Answer and see the solution →A solution has a pH of 2.5. State whether this solution is strongly acidic, weakly acidic, neutral, weakly alkaline, or strongly alkaline. Explain your answer using the pH range classifications.
Question 12
3 marks · Normal
Answer and see the solution →Explain why universal indicator is preferred over litmus paper when measuring the pH of a solution.
Question 13
4 marks · Normal
Answer and see the solution →A student tests four solutions using different indicators. Their observations are shown below.
Observations with indicators Solution Litmus Methyl Orange Universal Indicator A blue yellow blue B red red red C purple orange green D blue yellow green Complete the table below by identifying the likely pH or classification (acidic, neutral, or alkaline) for each solution.
Solution pH/classification A B C D Question 14
1 mark · Normal
Answer and check →Which pH value below would be classified as weakly alkaline?
- A.pH 12
- B.pH 9
- C.pH 7
- D.pH 3
Question 15
2 marks · Normal
Answer and see the solution →You are given a colourless solution that could be either hydrochloric acid or sodium hydroxide solution. Describe how you would use universal indicator to help identify which solution is which.
Question 16
4 marks · Normal
Answer and see the solution →(a)[2 marks]Complete the table to show the colour each indicator would turn in a neutral solution (pH 7).
Indicator Colour in Neutral Solution Litmus Methyl orange Phenolphthalein Universal indicator (b)[2 marks]Suggest why universal indicator is more useful than phenolphthalein for measuring the pH of a weakly acidic solution.
Question 17
2 marks · Hard
Answer and see the solution →State the colours shown by phenolphthalein in (i) a strongly acidic solution, and (ii) a strongly alkaline solution.
Question 18
5 marks · Hard
Answer and see the solution →For each pH value below, state whether the solution is strongly acidic, weakly acidic, neutral, weakly alkaline, or strongly alkaline.
(a)[1 mark]pH = 2
(b)[1 mark]pH = 5
(c)[1 mark]pH = 7
(d)[1 mark]pH = 9
(e)[1 mark]pH = 12
Question 19
2 marks · Hard
Answer and see the solution →Describe how you would use universal indicator paper to measure the pH of a solution as accurately as the method allows.