Titration
4 marks · NormalLook at the following table of titration results.
| Titration | Initial reading / cm³ | Final reading / cm³ |
|---|---|---|
| 1 | 1.50 | 23.40 |
| 2 | 2.20 | 24.10 |
| 3 | 1.70 | 23.60 |
Calculate the volume of sodium hydroxide used in each titration.
Suggest which, if any, of the three titrations should be considered an outlier. Give a reason.
State why titrations are repeated.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) T1: 21.90 cm³; T2: 21.90 cm³; T3: 21.90 cm³
(b) No outlier; all results are the same.
(c) To ensure reliability/accuracy of results.
Common mistakes: mixing up subtraction order; not justifying outlier
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Subtracts correctly: final - initial for each titration.
A1 (a) · 1 mark · All three volumes given correctly as 21.90 cm³ each.
B1 (b) · 1 mark · Identifies there is no outlier (or equivalent wording) with valid reason (results are same).
B2 (c) · 1 mark · States titrations are repeated for reliability or accuracy.
Worked solution
a) Calculate:
| Titration | Volume used / cm³ |
|---|---|
| 1 | 21.90 |
| 2 | 21.90 |
| 3 | 21.90 |
b) There is no outlier because all values are identical.
c) Titrations are repeated for accuracy and to spot anomalous results.