13/06/2012 - Microwave & Boiling Experiment

Microwave & Boiling Experiment

Aim of Experiment:

To find out the amount of time water takes to cool down to room temperature after being microwaved or boiled.

Apparatus:

·         1 microwave oven

·         1 1.6l water kettle/boiler

·         1 laboratory thermometer

·         1 500ml measuring cup

·         Tap water

·         1 microwaveable pot

·         1 microwaveable bowl (for trial experiment)

Steps of Actual Experiment:

1.       Fill measuring cup with 1.6l of tap water.

2.       Pour the measured amount of water into the microwaveable pot.

3.       Place the pot into the microwave oven.

4.       Set the timer to default.

5.       Start the microwave oven.

6.       If timer ends, and the amount of water does not reach boiling point of 100°c, continue the timer until a temperature of around 100°c is achieved.

7.       If timer ends, and the amount of water is over 100°c, steadily decrease the timer until a temperature of 100°c is reached.

8.       If timer ends, and the amount of water is around 100°c, move on to boil water in the boiler.

9.       Fill the boiler with 1.6l of water.

10.   Start the boiler.

11.   Once the boiler has stopped boiling the water, open the boiler.

12.   Measure the temperature of the water in the boiler.

13.   After every half hour, measure the temperature of water in the boiler.

14.   After every two and a half hours, measure the temperature of water in the microwave oven (see microwave trial experiment [above] for more details).

15.   Conclude experiment when the water reaches room temperature.

Data of Actual Experiment:

Microwave Oven – Actual Experiment

Default time = 4min 40s (maximum time)

Amount of water used = 1.6l

Room temperature of water = 29.5°c

Timer (4min 40s)	Temperature	Comments
2.18.45 p.m. – 2.23.25 p.m.	55°c	·
2.25.21 p.m. – 2.29.01 p.m.	71°c	·
2.29.54 p.m. – 2.34.34 p.m.	76°c	·
2.35.19 p.m. – 2.39.58 p.m.	90°c	Possible anomaly
2.41.02 p.m. – 2.45.42 p.m.	89°c	·
2.46.58 p.m. – 2.51.38 p.m.	94°c	·
2.53.01 p.m. – 2.57.41 p.m.	97°c	·

Note: Time lags between the timings given are used for opening and closing the microwave, and measuring the temperature of the water.  

Time	Temperature of Water	Comments
5.28.31 p.m. – 5.29.10 p.m.	42°c	·
7.59.10 p.m. – 7.59.34 p.m.	34°c	·

Note: The time recorded is time taken between opening and closing the door of the microwave oven.

Boiler – First time

Time taken to boil = 3min 57s

Room temperature of water = 31°c

Temperature after boiling = 99°c

Note: After some of the water was accidentally drunk by my family, the experiment restarted.

Boiler – Second time

Time taken to boil = 3min 52s

Room temperature of water = 31°c

Temperature after boiling = 98°c

Time	Temperature of Water	Comments
7.15.07 p.m. – 7.15.47 p.m.	98°c	·
7.45.47 p.m. – 7.46.32 p.m.	82°c	·
8.16.32 p.m. – 8.17.20 p.m.	71.5°c	·
8.47.20 p.m. – 8.48.05 p.m.	62°c	·
9.18.05 p.m. – 9.18.46 p.m.	56°c	·
9.48.46 p.m. – 9.49.30 p.m.	51°c	·
10.19.30 p.m. – 10.20.16 p.m.	48°c	·
10.50.16 p.m. – 10.50.51 p.m.	45°c	·
11.20.51 p.m. – 11.21.29 p.m.	43°c	·
11.51.29 p.m. – 11.51.56 p.m.	41°c	·
12.21.56 a.m. – 12.22.28 a.m.	39°c	·
12.53.28 a.m. – 12.53.07 a.m.	37.5°c	·
1.23.07 a.m. – 1.23.32 a.m.	36°c	·
1.53.07 a.m. – 1.53.32 a.m.	35°c	·
Total time: 6h 33min 25s

Note: The time recorded is time taken between opening the boiler and closing the boiler. 

Conclusion:

Due to restraints in equipment, there will be a difference between the temperatures of microwaved water and boiled water. However, it is noted that due to random errors the temperatures of water vary as seen above; thus, the difference is ignored.

Conclusively, the amount of time taken for 1.6l of water to cool down to around 35°c would be 5h in a microwave oven, and 6h 33min 25s in a boiler, which, when rounded to the nearest half hour, would be 6h 30min. It has also been determined that 6h 30min would indeed give 35°c in a boiler, as seen in the main experiment (below). Temperatures of around 35°c is accepted as the microwave trial experiment suggests that heated water continues to maintain a temperature of 35°c for a period of time in a microwave oven; thus, the experiment for the boiler is concluded once water reaches a temperature of around 35°c.

Part of the experiment has been recorded down; the part on the boiled water. The part on the microwaved water was added in today when I did it along with the main experiment.