Question

(iii) The filtrate was an alkaline solution of potassium carbonate. This was titrated

against a standard hydrochloric acid solution to find the concentration of the
potassium carbonate.
K₂CO3
+
2HC1
2KCI+ CO₂ + H₂O
Methyl orange was used as an indicator; this turns from yellow in the potassium
carbonate solution to pink when the potassium carbonate is neutralised by the
hydrochloric acid. The following results were obtained using 25.00 cm³ samples of
the potassium carbonate solution.
Burette finish/cm³
Burette start/cm³
24.80
0.00
26.20
1.60
26.55
2.00
I Calculate the mean volume of hydrochloric acid added, using all three sets
of results.
[1]

Answer 1

Step-by-step explanation:

The mean volume of hydrochloric acid added can be calculated by summing the volume of acid added in each titration and dividing by the number of titrations.

1st titration: 24.80cm³ - 0.00cm³ = 24.80cm³

2nd titration: 26.20cm³ - 1.60cm³ = 24.60cm³

3rd titration: 26.55cm³ - 2.00cm³ = 24.55cm³

Sum of volumes: 24.80cm³ + 24.60cm³ + 24.55cm³ = 74.95cm³

Mean volume: 74.95cm³ / 3 = 24.98cm³

So the mean volume of hydrochloric acid added is 24.98cm³.