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2001 - Q6

 

The graph shows the colour ranges of the acid-base indicators methyl orange, bromothymol blue and phenolphtalein.

 

 

 

 

 

 

 

 

 

 

 

A solution is yellow in methyl orange, blue in bromothymol blue and colourless in phenolphtalein.

 

What is the pH range of the solution?

 

(A) 4.5 to 6.0

(B) 6.0 to 7.5

(C) 7.5 to 8.5

(D) 8.5 to 10.0

2001 - Q7

 

A group of students produced a red solution by boiling red cabbage leaves in water. When dilute sodium hydroxide was added to the solution, it turned purple. When dilute hydrochloric acid was added to the red solution, no colour change occurred.

 

Which of these substances, when added, is most likely to cause the red solution to change colour?

 

(A) Cleaning solution containing ammonia

(B) Concentrated hydrochloric acid

(C) Orange juice

(D) Vinegar

2003 - Q1

 

Which of the following is an acid–base indicator?

 

(A) Methanol

(B) Methyl orange

(C) Methanoic acid

(D) Methyl ethanoate

2002 - Q20 (4 marks)

 

(a) Identify ONE common household base. (1 mark)

 

(b) A student used indicators to determine whether three colourless solutions were acidic or basic. The indicators used are shown in the table.

 

 

 

 

 

 

 

 

 

 

 

Samples of each solution were tested with the indicators. The colours of the resulting solutions are shown in the table.

 

 

 

 

 

 

 

 

 

 

The student concluded that each of the three solutions tested was basic. 

Assess the validity of this conclusion. (3 marks)

2004 - Q23 (3 marks)

 

A natural indicator was made by heating yellow flowers with water. The resulting yellow solution was tested with a range of substances. The results are recorded below.

 

    Substance                                 Colour

0.1 M hydrochloric acid                 Red

0.1 M ammonia                           Yellow

Lemon juice                                 Orange                                 

Oven cleaner                               Yellow

Pure water                                   Yellow

 

Assess the usefulness of the yellow solution as an acid–base indicator.

2007 - Q6

 

Which aqueous solution turns phenolphthalein pink?

 

(A) HCl

(B) NaCl

(C) NaOH

(D) CH3OH

2009 - Q3

 

Which of the following groups contains ONLY acidic substances?

 

(A) Antacid tablets, baking soda, laundry detergents

(B) Blood, oven cleaner, seawater

(C) Milk, tea, drain cleaner

(D) Vinegar, wine, aspirin

2010 - Q3

 

Which substance shows the correct indicator colour?

 

             Substance        pH           Indicator           Colour

(A)      Stomach acid      2       Methyl orange       Yellow

(B)        Lemon juice      3      Phenolphthalein       Pink

(C)         Soda water       4      Phenolphthalein      Pink

(D)         Seawater          8        Methyl orange      Yellow

2011 - Q3

 

Which of the following lists contains ONLY basic substances?

 

(A) Oven cleaner, urine, vinegar

(B) Lemonade, drain cleaner, blood

(C) Baking soda, ammonia, sea water

(D) Antacid, dishwashing detergent, lemon juice

2012 - Q7

 

Methyl orange, bromothymol blue and phenolphthalein indicators were mixed together to form a solution.

 

 

 

 

 

 

 

 

 

 

 

 

 

Over what pH range would the solution be yellow?

 

(A) 0 – 14

(B) 3 – 4.5

(C) 3 – 7.5

(D) 4.5 – 6

2013 - Q19

 

A solution was obtained by boiling flowers in water. After various substances were added to separate samples of the solution, the colour of each was noted.

 

                       Substance added                          Colour observed

                        0.1 mol L–1 HCl(aq)                            Bright pink

                      0.01 mol L–1 HCl(aq)                            Bright pink

                      0.001 mol L–1 HCl(aq)                          Pale yellow

                          Distilled water                                   Bright yellow

                   0.001 mol L–1 NaOH(aq)                         Bright yellow

                     0.01 mol L–1 NaOH(aq)                         Bright yellow

 

For which of the following titrations would it be appropriate to use this solution as an indicator?

 

(A) HCl(aq) + NH3(aq)

(B) HCl(aq) + NaOH(aq)

(C) CH3COOH(aq) + NH3(aq)

(D) CH3COOH(aq) + NaOH(aq)

2006 - Q23 (6 marks)

 

Correct swimming pool maintenance requires regular monitoring of the pH level of the water.

 

(a) Select the best indicator from the graph to check that the pH of swimming pool water lies within the correct range of 7.0 – 7.6. 

Justify your choice. (3 marks)

 

 

 

 

 

 

 

 

 

(b) Another part of swimming pool maintenance is adjusting chlorine levels in the pool. ‘Liquid chlorine’ is a solution of sodium hypochlorite (NaOCl) which can be used to do this. Upon addition of sodium hypochlorite to the pool, the following equilibrium reaction occurs:

 

OCl– (aq) + H2O(l) <--->  HOCl(aq) + OH– (aq)

 

(i) State a reason for the regular chlorination of swimming pool water. (1 mark)

 

(ii) Explain how the addition of sodium hypochlorite will affect the pH of the water in the pool. (2 marks)

2011 - Q32 (5 marks)

 

To determine the pH of garden soil, a sample was first saturated with distilled water in a petri dish. Barium sulfate powder was added to the surface of the sample, and drops of the three indicators listed below were added to separate parts of the sample. The colours observed are shown in the table.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(a) Why is barium sulfate powder added when testing soil pH? (1 mark)

 

(b) Using the information given, select the plant that will grow well at the current soil pH, and justify your selection. (2 marks)

 

(c) Outline the method you would use to test a natural indicator that has been prepared in the school laboratory. (2 marks)

2013 - Q25 (4 marks)

 

An indicator is placed in water. The resulting solution contains the green ion, Ind- , and the red molecule, HInd.

 

Explain why this solution can be used as an indicator. In your response, include a suitable chemical equation that uses Ind- and HInd.

2015 - Q21 (4 marks)

 

(a) Outline a suitable method to prepare a natural indicator. (2 marks)

 

(b) How could a natural indicator be tested? (2 marks)

2014 - Q7

 

This table contains information on three indicators.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Which of the following substances will produce these results?

 

(A) Lemonade      pH 2.9

(B) White wine    pH 4.2

(C) Tap water      pH 7.2

(D) Ammonia      pH 11.2

 

2016 - Q7

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Which indicator in the table would be best for distinguishing between lemon juice (pH = 2.3) and potato juice (pH = 5.8)?

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