Describe4 marksStandard
A student investigates the effect of pH on the activity of amylase. Two buffers of pH 7 and pH 9 are each mixed with a starch solution and the same volume of amylase. At regular intervals, a sample is removed and immediately mixed with iodine solution. The absorbance of each sample is measured at 620 nm using a colorimeter. The results are shown in the table.
| Time / s | Absorbance at pH 7 | Absorbance at pH 9 |
|---|---|---|
| 0 | 0.85 | 0.85 |
| 30 | 0.60 | 0.72 |
| 60 | 0.35 | 0.60 |
| 90 | 0.15 | 0.50 |
| 120 | 0.05 | 0.42 |
Describe how a colorimeter can be used in this investigation and how the results in the table can be used to compare the rates of reaction at the two pH values.