Question 1
Which are the Brønsted-Lowry acids in the following equilibrium?
CH3COOH + C2H5COOH ⇌ CH3COO- + C2H5COOH2+
CH3COOH and C2H5COOH
CH3COOH and C2H5COOH2+
C2H5COOH2+ and CH3COO-
CH3COO- and C2H5COOH2+
|
Question 2
A solution of hydrochloric acid has pH = 2.
The solution is diluted to one tenth of its original concentration.
What is the pH of the diluted solution?
0.70
1.0
2.7
3.0
|
Question 3
Which two solutions, both of concentration 0.10 mol dm-3, have been used to produce this titration curve?
HCl(aq) and KOH(aq)
HCOOH(aq) and KOH(aq)
HCl(aq) and NH3(aq)
HCOOH(aq) and NH3(aq)
|
Question 4
When equimolar amounts of the solutions below are mixed, which forms a buffer solution with a pH less than 7?
hydrochloric acid and sodium chloride
ethanoic acid and sodium ethanoate
sodium hydroxide and sodium chloride
ammonia and ammonium chloride
|
Question 5
Ammonia reacts with water in a reversible reaction. Which are the Brønsted-Lowry bases?
H2O and OH-
NH3 and OH-
NH4+ and OH-
NH4+ and NH3
|
Question 6
The indicator methyl orange is a weak acid and may be represented by the formula HA(aq). The equation for its dissociation is shown below.
HA(aq) ⇌. A- + H+(aq)
Colour: Red Yellow
Under certain conditions, at equilibrium, a solution of HA has a yellow colour.
On addition of a small volume of dilute sodium hydroxide, the colour of this solution would
change from yellow to red
change from yellow to orange
change from yellow to orange and then to red
not change
|
Question 7
20 cm3 of 0.10 mol dm-3 hydrochloric acid is added to 10 cm3 of 0.10 mol dm-3 sodium hydroxide.
What is the pH of the resulting mixture?
1.00
1.18
1.30
1.48
|
Question 8
The equation shows the dissociation of the acid H3AsO4 in water.
H3AsO4 + H2O ⇌ H2AsO4- + H3O+
Which pair is a conjugate acid–base pair?
H3AsO4 and H2O
H2AsO4- and H3O+
H3AsO4 and H3O+
H3O+ and H2O
|
Question 9
A buffer solution is prepared by mixing 200 cm3 of 2.00 mol dm-3 propanoic acid, CH3CH2COOH, with 600 cm3 of 1.00 mol dm-3 sodium propanoate, CH3CH2COONa.
Ka for CH3CH2COOH = 1.32 × 10-5 mol dm-3
What is the pH of the buffer solution?
4.58
4.70
5.06
5.18
|
Question 10
2,4,6-Trichlorophenol is a weak monoprotic acid, with Ka = 2.51 × 10-8 mol dm-3 at 298 K.
What is the concentration, in mol dm-3, of hydrogen ions in a 2.00 × 10-3 mol dm-3 solution of 2,4,6-trichlorophenol at 298 K?
5.02 × 10-11
7.09 × 10-6
1.26 × 10-5
3.54 × 10-3
|
Question 11
What is the pH of a 0.46 mol dm-3 solution of potassium hydroxide at 298 K?
Kw = 1.0 × 10-14 mol2 dm-6 at 298 K.
0.34
13.66
13.96
14.34
|
Question 12
The diagram shows a pH curve produced by adding a strong alkali to a weak acid.
Which point on the curve represents a solution that can act as a buffer?
|
Question 13
The acid dissociation constant, Ka, of a weak acid HA has the value 2.56 × 10-4 mol dm-3
What is the pH of a 4.25 × 10-3 mol dm-3 solution of HA?
5.96
3.59
2.98
2.37
|
Question 14
Which statement about pH is correct?
the pH of a weak base is independent of temperature
at temperatures above 298 K, the pH of pure water is less than 7
the pH of 2.0 mol dm-3 nitric acid is approximately 0.30
the pH of 0.10 mol dm-3 sulfuric acid is greater than that of 0.10 mol dm-3 hydrochloric acid.
|
Question 15
A 0.10 mol dm-3 aqueous solution of an acid is added slowly to 25 cm3 of a 0.10 mol dm-3 aqueous solution of a base.
Which acid–base pair has the highest pH at the equivalence point?
CH3COOH and NaOH
CH3COOH and NH3
HCl and NaOH
HCl and NH3
|
Question 16
Which is the concentration of NaOH(aq), in mol dm-3, that has pH = 14.30?
Kw = 1.00 × 10-14 mol2 dm-6 at 25°C
-1.16
5.01 × 10-15
2.00 × 1014
2.00
|
Question 17
What is the pH of 0.015 mol dm-3 sulfuric acid?
-1.82
-1.52
1.52
1.82
|