Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Acids, Alkalis and Titrations
83 practice questions
Topics covered
Practice questions
31–40 of 83
Question 31
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 32
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 33
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 34
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 35
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 36
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 37
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 38
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.
Question 39
1 mark · Easy
Answer and see the solution →State the ion responsible for the alkalinity of sodium hydroxide solution.
Question 40
3 marks · Easy
Answer and see the solution →Potassium carbonate ([32mK_2CO_3[0m) can make water alkaline without containing hydroxide ions in its formula.
(a)[1 mark]Write the formula of the ion that makes a solution alkaline.
(b)[2 marks]Explain, using a chemical equation, how potassium carbonate forms an alkaline solution in water.