There are a number of ways that you could carry out an accurate acid-alkali titration. Different acids and alkalis could be used in this practical. This outlines one way to carry out the practical using sodium hydroxide solution and hydrochloric acid.
It is important in this practical to use appropriate apparatus to make and record volumes accurately. This includes the safe use and careful handling of substances, such as when mixing.
To investigate the relative concentrations of a solution of an alkali (eg sodium hydroxide) and a solution of an acid (eg hydrochloric acid).
Record the burette volumes in a suitable table. For example:
|Run||End vol||Start vol||Acid used vol|
|Rough||26.00 cm3||1.00 cm3|
|1||25.60 cm3||0.00 cm3|
|2||25.80 cm3||0.00 cm3|
What is the mean volume of hydrochloric acid which reacts with 25 cm3 of sodium hydroxide in this practical?
The volume of hydrochloric acid used is (25.60 + 25.80) ÷ 2 = 25.70 cm3.
What do your results tell you about the concentration of the acid?
The volume of acid used was slightly larger than the volume of the alkali. Therefore the acid must be slightly less concentrated than the alkali.
How could this experiment be adapted to make a pure sample of sodium chloride?
25 cm3 of sodium hydroxide solution would be reacted with 25.70 cm3 of hydrochloric acid with no indicator. This would make a solution of pure sodium chloride, which would be evaporated to leave the solid salt.
It is important in this practical activity to use appropriate apparatus and methods. This includes the safe use and careful handling of substances.
Evaluate the hazards and the precautions needed to reduce the risk of harm. For example:
|Hydrochloric acid and sodium hydroxide solution||Both solutions are corrosive and damage skin and clothes||Use dilute solutions, wear eye protection, wash hands after contact with solutions|
|Burette and pipette||May break when used, producing broken glass that could cut||Take care, especially when clamping the burette|