Monday 6 June 2011

Effect of temperature - 2nd experimental plan

I changed the experimental procedure as the old procedure would have resulted in confusing results. In changing the procedure, I also changed the materials and apparatus needed for the experiment.

New materials:
- Freshly squeezed orange juice
- 3 boiling tubes
- Aluminum foil
- Cling wrap
- Data logger with pH probe
- Test tube rack

New procedure:
Step 1: Squeeze fresh orange juice.
Step 2: Take initial pH of orange juice and record it down.
Step 3: Pour orange juice equally into 3 boiling tubes, each 1/3 a boiling tube.
Step 4: Immediately cover the top of all the boiling tubes with aluminum foil and cling wrap.
Step 5: Put one setup in the fridge, one in the freezer and one in room temperature. (Measure their exact temperatures)
Step 6: Leave setups in respective locations for 3 hours and record the pH level of the juice every 15 minutes with the help of the data logger and pH probe.
Step 7: Construct a table for each set of data and then plot separate graphs of pH level against time.
Step 8: Repeat entire experiment once more.

Firstly, I realised that with the old experiment procedure, both setups (one left in the fridge, one held over a flame) would take different amounts of time to achieve the desired results. The temperature change would be faster in the orange juice sample held over the flame as it would take less time for it to heat up and for the results to be logged by the data logger. However, the sample left in the fridge would take a longer time for the juice to cool down and its temperature to reach a standstill, for us to observe the results. Due to this, the results may be affected by how long the change in pH of the orange juice samples are being monitored. The longer the orange juice is being observed, the more of the vitamin C content degrades.

With this new experiment procedure, all the orange juice samples are kept at different constant temperatures, being monitored for the same amount of time. This will make sure that difference in time does not affect the results collected, and still allow us to see how difference in temperature affects the retention of vitamin C in orange juice.

No comments:

Post a Comment