Procedure
1. Standardize the 0.0200 N sulphuric acid as described
2. Gently transfer 100.0 ml of sample into a 250 ml erlenmyer flask. N.B. This Procedure is to be done in duplicate.
3. Add 4 drops of phenolphthalein indicator to the sample. If a pink color appears,hydroxide or normal carbonate are present. If no pink color appears proceed to next titration step.
4. Titrate with the 0.0200 N sulphuric acid until the color just disappears. Record the ml of acid used.
5. If on pink color appears with the addition of the phenolphthalein, or after the completion of the phenolphthalein titration, add 2 drops of bromocresol green methyl red indicator to the sample and continue to titrate with acid until the color changes from blue/gray to a “clear orange”
6. Record the final (total) volume of the acid titrant used.