Indicator | pKa |
Methyl orange | 3.7 |
Phenolphthalein | 9.6 |
Phenol red | 7.9 |
Bromothymol blue | 7.0 |
The pH range of four different indicators are given in the table. Which indicator would be suitable for a titration involving hydrochloric acid and ammonia?
Methyl orange
Phenolphthalein
Phenol red
Bromothymol blue
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Which type of titration is indicated by the pH curve above?
Strong acid - strong base
Weak acid - weak base
Strong acid - weak base
Weak acid - strong base
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A 0.10 mol dm-3 solution of propanoic acid is titrated with 0.10 mol dm-3 potassium hydroxide.
Which of the following statements accurately describes this titration
The equivalence point occurs at pH 7.
The salt formed hydrolyzes to form an acidic salt.
The salt formed at the equivalence point is CH3COOK.
At the half-equivalence point, [CH3CH2COOH] = [CH3CH2COO-].
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During a titration, 23.70 cm3 of 0.02 mol dm-3 potassium hydroxide (KOH) is used to completely neutralize 0.03 mol dm-3 sulfuric acid (H2SO4).
What is the required volume of H2SO4 solution to reach the equivalence point?
7.90 cm3
31.65 cm3
15.80 cm3
17.78 cm3
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The table below shows the pKa values of four acid-base indicators:
Indicator | pKa |
Methyl orange | 3.7 |
Phenolphthalein | 9.6 |
Phenol red | 7.9 |
Bromothymol blue | 7.0 |
Which indicator would be most appropriate for a titration between hydrochloric acid and ammonia?
Methyl orange
Phenolphthalein
Phenol red
Bromothymol blue
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In a titration, the equivalence point is reached when 23.70 mL of 0.02 M potassium hydroxide reacts with 0.03 M of sulfuric acid. What volume of acid is needed?
7.9 mL
31.65 mL
15.80 mL
17.78 mL
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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(s) is/are 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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The pH curve above represents a weak acid, strong base titration. The pH of the acid at half equivalence point is 4.90.
What is the Ka of the acid?
4.90
8.72
1.26 x 10-5
1.91 x 10-9
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A titration is carried out using 25.00 cm3 of 0.100 mol dm-3 propanoic acid and 0.100 mol dm-3 sodium hydroxide. Phenolphthalein (pH range: 8.3 – 10.0) is used to determine the equivalence point.
If 0.100 mol dm-3 hydrochloric acid is used instead of propanoic acid, which of the following remains unchanged?
The volume of base required to reach the equivalence point.
The pH at the equivalence point.
The y-intercept of the pH curve.
The color of the solution just before equivalence is reached.
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The pKb value of HPO42- is 6.8.
What is its conjugate acid and what is the Ka value?
H2PO4-, 7.2
H3PO4, 7.2
H3PO4, 1.67 x 10-7
H2PO4-, 6.3 x 10-8
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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 table below shows data for the and values for some acids and bases at 298 K.
Acid | Ka | Base | pKb |
C5H6OH | 1.02 x 10-10 | (C2H5)3N | 3.25 |
O2NC6H4OH | 7.08 x 10-8 | C6H5NH2 | 9.13 |
Which two formulas represent the weakest acid and the weakest base in the table?
C5H6OH and C6H5NH2
O2NC6H4OH and C6H5NH2
O2NC6H4OH and (C2H5)3N
C5H6OH and (C2H5)3N
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