Experiment : To use this standard sodium carbonate solution to find the concentration of (standardise) a given hydrochloric acid solution.
Procedure
- Place 20 ml of 0.0.48 Molar sodium carbonate into a conical flask using a pipette.
- Add two drops of methyl red indicator. This will give a yellow colour to the solution. Note: the number of drops of indicator should be kept to a minimum as most indicators are either weak acids or bases and will therefore take part in the neutralisation process.
- Place the hydrochloric acid in the burette and adjust the level to zero, taking all of the usual precautions.
- Titrate in the usual manner.
- Record the volume of acid required to neutralise the sodium carbonate. The point of neutralisation is reached when the indicator just turns red (pink).
- Repeat the titration several times until two titration values agree to within 0.2 ml of each other.
Equation for the titration
Results
- Volume of the acid = 19.2 ml
- Factor for the acid = 2 (the number in front of HCl in the balanced equation)
- Molarity of the acid = ?
- Volume of the base = 20 ml
- Factor for the base = 1 (the number in front of sodium carbonate in the balanced equation)
- Molarity of the base = 0.048 M
Calculations
