Titration
3 marks · EasyDescribe how you would add the alkali during a titration to obtain an accurate result.
Explain why the conical flask should be swirled during the titration.
State how the endpoint of the titration is recognised.
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(a) Add alkali slowly near the endpoint, dropwise.
(b) To mix the reactants thoroughly.
(c) By a sharp colour change in the indicator.
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Marking points
M1 (a) · 1 mark · Describes adding alkali slowly, dropwise, as endpoint approaches.
M1 (b) · 1 mark · States reason for swirling: to mix thoroughly.
B1 (c) · 1 mark · Correctly describes the endpoint is seen by a sharp colour change in the indicator.
Worked solution
(a) Add alkali quickly at first, then dropwise near the endpoint for accuracy.
(b) Swirl to make sure the acid and alkali mix and react completely.
(c) The endpoint is recognised by a sudden colour change in the indicator.