Syllabus Edition

First teaching 2014

Last exams 2024

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Further Aspects of Acids & Bases (DP IB Chemistry: HL)

Exam Questions

3 hours29 questions
1
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1 mark

Which definition of a Lewis acid is correct?

  • Electron pair donor

  • Electron pair acceptor

  • Proton donor

  • Proton acceptor

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2
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1 mark

Which type of titration is indicated by the following pH curve?

PH curve

  • Strong acid - strong base

  • Weak acid - weak base

  • Strong acid - weak base

  • Weak acid - strong base

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3
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1 mark

Which of the following best describes ammonia, NH3 , in the following equation?

BF+ NH3 → BF3NH3

  • Lewis acid 

  • Lewis base

  • Coordinate bond

  • Brønsted-Lowry acid 

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4
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1 mark

Which mixture cannot act as a buffer?

  • CH3COOH (aq) and CH3COONa (aq) 

  • CH3CH2COOH (aq) and CH3CH2COONa (aq) 

  • HNO3 (aq) and NaOH (aq)

  • NH3 (aq) and NH4Cl (aq) 

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5
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1 mark

The hydrolysis of ammonium chloride takes place via the following reaction.

NH4+ + H2O → H3O+ + NH3

Which of the following is correct? 

  • The resultant pH is above 7

  • The resultant pH is 7

  • The resultant pH is below 7

  • Ammonium chloride is insoluble

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11 mark

Which of the following statements is not correct?

  • A Brønsted-Lowry base is a proton acceptor

  • Ammonia can act as a Brønsted-Lowry base and Lewis base

  • A Lewis acid is an electron pair acceptor 

  • A hydroxide ion can only act as a Lewis base

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21 mark

Which of the following statements are correct for a titration between 0.10 mol dm-3 propanoic acid and 0.10 mol dm-3 potassium hydroxide? 

  • The equivalence point will be at pH 7

  • The salt formed will hydrolyse to form an acidic salt 

  • The salt formed will be CH3COOK

  • At half equivalence point [CH3CH2COOH (aq)] = [CH3CH2COO- (aq)]

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31 mark

Which of the following statements about indicators are correct? 

  1.  The pKa of the indicator is the midpoint of the pH range
  2.  The colour of the indicator depends upon the pH of the solution
  3.  At the end point of a titration [HIn] = [In-]
  • I and II only

  • I and III only 

  • II and III only

  • I, II and III

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41 mark

Which statement about buffer solutions is not correct?

  • A buffer resists small changes in pH

  • A buffer can be formed from sodium hydroxide and an excess of ethanoic acid

  • The pH during a titration between a strong acid and weak base changes slowly in the buffer region 

  • When a strong acid is added to a buffer, hydrogen ions react with salt ions 

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51 mark

The pH range of four different indicators are:

Indicator

pKa

Methyl orange

3.7

Phenolphthalein

9.6

Phenol red

7.9

Bromothymol blue

7.0

Which indicator would be suitable for a titration involving hydrochloric acid and ammonia?

  • Methyl orange

  • Phenolphthalein

  • Phenol red

  • Bromothymol blue

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1
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1 mark

Using appropriate molar ratios which mixtures could act as buffers?

I. NaOH and CH3COOH

II. CH3NH2 and CH3NH3Cl

III. NH3 and HCl

  • I and II only

  • I and III only

  • II and III only

  • I, II and III

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2
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1 mark

Consider the following equation

AgCl + 2NH3→ [Ag(NH3)2]+ + Cl-

Which of the following statements is correct?

  • Silver is acting as a Lewis base

  • AgCl is acting a Lewis base

  • NH3 is acting as a Brønsted-Lowry base

  • Silver ions are acting as a Lewis acid

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3
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1 mark

Which of the following salts would produce a solution with the highest pH if dissolved in water?

  • RbCl

  • CuSO4

  • KCl

  • Na2CO3

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4
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1 mark

The acid–base indicator bromophenol blue changes colour from yellow to blue over a pH range of 3.0–4.6. Which statement is correct?

I. The pKa is between 3.0 and 4.6

II. In a neutral solution [HIn] > [In-]

III. It is a suitable indicator for a strong acid, weak base titration

  • I and II only

  • I and III only

  • II and III only

  • I, II and III

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5
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1 mark

A titration was carried out using 25.00 cm3 of 0.100 mol dm-3 propanoic acid with 0.100 mol dm-3 sodium hydroxide. The indicator phenolphthalein was used to determine the equivalence point. Phenolphthalein has a pH range of 8.3 to 10.0.  

If hydrochloric acid was used instead of propanoic acid of the same concentration, which of the following would remain the same? 

  • The volume of base needed to reach the equivalence point

  • The pH at the equivalence point 

  • The y intercept on the pH curve

  • The colour of the solution just before equivalence had been reached 

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