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15 questions
Which one of the following is the change in units of pH which occurs when 10.0 cm3 of a 1.0 M solution of a strong monoprotic acid are made up to 1.0 dm3 with water?
1
2
3
5
Addition of which one of the following to 10 cm3 of 1.0 M NaOH would result in the pH being halved?
10 cm3 of water
100 cm3 of water
5 cm3 of 1.0 M HCl
10 cm3 of 1.0 M HCl
The pH of 0.001 M NaOH at 25°C is
13
11
9
3
An aqueous solution contains 4.0 g of sodium hydroxide in 250 cm3 of solution. (Kw = 1.00 × 10−14 mol2 dm−6) The pH of the solution is
13.0
13.3
13.6
13.9
Which one of the following could be true in an aqueous solution of sodium hydroxide?
[H+] = (OH−]
pH = −log10 [OH−]
pH = 1.2
pH = 12.8
A solution of sodium ethanoate has a pH of 8.91 at 25 °C. The hydrogen ion and hydroxide ion concentrations in this solution are ...
[H+] = 1.00 × 10−9 mol dm−3 [OH−] = 1.00 × 10−5 mol dm−3
[H+] = 1.00 × 10−9 mol dm−3 [OH−] = 8.13 × 10−6 mol dm−3
[H+] = 1.23 × 10−9 mol dm−3 [OH−] = 1.00 × 10−5 mol dm−3
[H+] = 1.23 × 10−9 mol dm−3 [OH−] = 8.13 × 10−6 mol dm−3
A weak acid HA dissociates in aqueous solution as shown below
HA(aq) ⇌ H+(aq) + A−(aq) ∆H = +20 kJ mol−1
Which one of the following changes will result in a decrease in the pH of an aqueous solution of the acid?
addition of a little aqueous sodium hydroxide solution
raising the temperature of the solution
dissolving a little of the sodium salt, NaA, in the solution
adding a platinum catalyst to the solution
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
What is the pH of a 0.020 mol dm–3 solution of a diprotic acid which is completely dissociated?
1.00
1.40
1.70
4.00
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
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
Use the information below to answer this question.
A saturated solution of magnesium hydroxide, Mg(OH)2, contains 0.1166 g of Mg(OH)2 in 10.00 dm3 of solution. In this solution the magnesium hydroxide is fully dissociated into ions.
Which one of the following is the pH of a solution of magnesium hydroxide containing 4.0 × 10−5 mol dm−3 of hydroxide ions at 298 K?
(Kw = 1.0 × 10−14 mol2 dm−6 at 298 K)
9.6
9.5
8.6
8.3
This question is about the following reaction scheme which shows the preparation of polymer P.
K is a weak acid with a pKa of 9.95. The pH of a 0.10 mol dm−3 solution of K is
4.48
4.98
5.48
5.98
Which indicator should be used in a titration to find the concentration of a solution of methylamine using 0.010 mol dm–3 hydrochloric acid?
Thymol blue (pH range 1.2–2.8)
Bromophenol blue (pH range 3.0–4.6)
Phenol red (pH range 6.8–8.4)
Phenolphthalein (pH range 8.3–10.0)
The table shows the pKa values for two acids. Which statement is correct?
Propanoic acid is a stronger acid than butanoic acid.
The value of Ka for propanoic acid is greater than that for butanoic acid.
The value of Ka for propanoic acid is 1.35 × 10−5 mol dm−3
The value of Ka for butanoic acid is 6.61 × 104 mol dm−3
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