Which definition of a Lewis acid is correct?
Electron pair donor
Electron pair acceptor
Proton donor
Proton acceptor
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Syllabus Edition
First teaching 2014
Last exams 2024
Which definition of a Lewis acid is correct?
Electron pair donor
Electron pair acceptor
Proton donor
Proton acceptor
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Which type of titration is indicated by the following pH curve?
Strong acid - strong base
Weak acid - weak base
Strong acid - weak base
Weak acid - strong base
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Which of the following best describes ammonia, NH3 , in the following equation?
BF3 + NH3 → BF3NH3
Lewis acid
Lewis base
Coordinate bond
Brønsted-Lowry acid
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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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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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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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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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Which of the following statements about indicators are correct?
I and II only
I and III only
II and III only
I, II and III
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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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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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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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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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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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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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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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