Tesr learner’s knowledge of acids and bases
The topics covered in this Starter for ten activity are: pH and Kw, pH and acids, pH and bases, acid-base titrations, buffer solutions and more complex buffer solutions.
Example question
Complete the table below showing some numbers and their common logarithmic values.
Number (n) | log10 n |
---|---|
0.001 | |
0.1 | |
0 | |
3 |
As water is always slightly ionised, we can write the following equilibrium for water;
H2O(l) ⇌ H+(aq) + OH–(aq) ΔH = +ive
As only a very small amount of the water is ionised, we define a new equilibrium constant for this equilibrium called the ionic product of water, Kw;
Kw = [H+(aq)] [OH–(aq)]
Like any other equilibrium constant, the value of Kw depends on the temperature of the equilibrium.
(a) Predict what effect increasing the temperature will have on the pH of pure water.
Calculate the pH of pure water (to 2 dp) at each of the temperatures below;
(i) 10 °C, Kw = 0.29 × 10–14 mol2 dm–6
(ii) 25 °C, Kw = 1.01 × 10–14 mol2 dm–6
(iii) 40 °C, Kw = 2.92 × 10–14 mol2 dm–6
Complete the paragraph below;
As the temperature decreases, water becomes (more acidic / less acidic / remains neutral).
Explain your answer
Notes
The full question and answer sheet are available from the ‘Downloads’ section below. An editable version is also available.
Downloads
Acids and bases
PDF, Size 0.48 mbAcids and bases - editable
Word, Size 0.28 mb
Starters for 10: Advanced level 2 (16–18)
- 1
- 2
- 3
- 4Currently reading
Acids and bases
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
No comments yet