APPARATUS AND MATERALS 250 mL and 500 mL beaker 50 mL burette Magnetic stirrer pH meter Measuring cylinder 0.1 M of NaOH solution 30 mL of weak acid Burette clamp Hot plate Retort stand and clamp

PROCEDURE

1. 0.1 M NaOH was filled into the burette until fill the burette.2. 10 ml of unknown acid was put into 250 ml beaker. 75 ml of distilled water was added to cover the pH electrode during reading process.3. The initial pH of unknown acid was taken and recorded.4. 1 ml of NaOH solution was added into unknown acid and the pH was recorded by using pH meter.5. Step 4 was repeated for every 1ml of NaOH titrated until the unknown acid was completely neutralized with NaOH solution.6. The graph of pH versus volume of NaOH was plotted and the volume of NaOH solution needed to neutralize unknown acid was determined. 7. To find Ka, pKa was determined by examining the titration curve. The negative log of the Ka is pKa and is the same as the pH at half the equivalence point volume. The value of pKa was compared to those in the table to find the identity of the unknown acid.

REFERENCES

Lab manual