The most commonly used acids in laboratories are hydrochloric, sulphuric and nitric acids. The concentration of these commercially available acids are 12M, 18M and 16M respectively. But except a few cases, you need these acids in lower concentrations. The acids in their lower concentrations can be obtained by dilution of concentrated acids.
To make a solution of required concentration, use the standard relation
M1V1 = M2V2
M1 = molarity of concentrated acid and V1 = Volume of concentrated acid
M2 = Molarity of acid required and V2 = Volume of acid required
Experiment: To prepare dilute solutions of given concentrations of hydrochloric acid, sulphuric acid and nitric acid from their stock solution.
How To Perform Experiment
From the commercially available acids, you are required to prepare:
- 100 mL of 1 molar solution of hydrochloric acid
- 100 mL of 0.5 molar solution of sulphuric acid
- 100 mL of 2 molar solution of nitric acid
For preparing 100 mL of 1 molar hydrochloric acid,
M1V1 = M2V2
First calculate the volume of concentrated acid and water required.
- M1 = molarity of concentrated acid = 12M
- V1 = Volume of concentrated acid = ?
- M2 = Molarity of acid required acid = 1M
- V2 = Volume of acid required = 100 mL
So, V1 = M2V2/M1 = 8.3 mL
Take about 50 mL of distilled water in a 100 mL standard flask. Transfer 8.3 mL of concentrated acid from a burette to the standard flask. Shake the mixture gently.
Add water to make up the volume of acid in the standard flask up to the mark. Close the flask with glass-stopper. Mix the solution by tilting the flask upside down.
For the preparation of dilute solution of sulphuric and nitric acids, follow the same procedure.
- The acids should be used with utmost care.
- All the three acids are corrosive to skin.
- Add concentrated acids slowly to water with constant stirring.