An experiment to measure the specific heat capacity of water
Extracts from this document...
Introduction
An Experiment to measure the Specific Heating Capacity of Water by electrical heating
Method
Put a known mass of water in a beaker and then immerse the heating coil in the water. Connect the heating coil to a DC power supply. Include an ammeter and a voltmeter in the circuit to measure the current through the coil and the voltage across it. Switch on the current in the coil and leave it until a reasonable temperature increase has been recorded.
Measurements
We recorded the starting temperature and the highest temperature reached during the experiment. We recorded the time for which the current was flowing and we measured the current and voltage throughout the heating interval. We recorded all of our measurements which are shown below.
Before commencing the experiment, we considered what precautions we could take to ensure accuracy. First we changed to a smaller beaker as this would give us less volume of water to heat, enabling us to complete the experiment within the designated time. We also felt that we gained the following advantages
- Less water surface area = less heat loss from water
- Less beaker surface area = less heat loss from beaker
& less heat to warm up beaker
- Less water volume = less risk of uneven heating
Middle
13.5
1
1.89
9.92
14.0
2
1.89
9.94
14.5
3
1.89
9.95
16.0
4
1.89
9.95
16.5
5
1.89
9.95
20.0
6
1.89
9.94
22.0
7
1.89
9.96
22.0
8
1.89
9.94
25.0
9
1.89
9.93
27.0
10
1.87
9.90
28.0
11
1.87
9.91
30.0
12
1.88
9.92
31.0
13
1.89
9.94
33.0
14
1.88
9.90
34.0
14m 30.39s
1.88
9.90
34.5
18m 50.00s
Not Applicable
Not Applicable
36.0
We stopped collating information at 14m 30.39s as we had reached our target temperature. At this point the power supply was turned off. We did however continue to time the increase in temperature until it started to drop, this being the maximum temperature reached by the water. We recorded this at a time of 18m 50.00 secs.
At this point, we weighed the beaker and water again.
Beaker plus warm water = 295.89g
Conclusion
Errors
Source of error | Average | ½ smallest division | ½ range | Use | % |
Mass of Water (g) | 200.1 | +/- 0.005 | (200.28-199.91) = 0.185 2 | 0.185 | 0.1 |
Change in water temperature (ºC) | 22.5 | (+/- 0.25) + (+/- 0.25) =0.5 | Not applicable | +/- 0.5 | 2.2 |
Current (I) | 1.89 | +/- 0.005 | (1.89-1.87) =0.01 2 | 0.01 | 0.5 |
Voltage (v) | 9.93 | +/- 0.005 | (9.96 – 9.90) = 0.03 2 | 0.03 | 0.3 |
Time (secs) | 930.39 | +/- 0.005 | Not applicable | +/- 0.005 | 0.0000054 |
Total % error | 3.1 | ||||
After considering the above table of errors, we amend our figure for Specific Heat Capacity of water as follows
3880.28 +/- (3.1% x 3880.28) = 3880.28 +/- 120.28 j/kgºC
The largest source of error in reaching this solution was the thermometer used to read the temperature, as it was the ½ division that we used to calculate the error. In order to improve this in a repeat experiment, we would need to find a more accurate thermometer.
Ideas for further research
We could consider the Specific Heat Capacity of water in different environments eg. Under pressure? Surrounding temperature – extreme heat versus extreme cold?
We could compare the Specific Heat Capacity with that of other substances to investigate the differences and why the Specific Heat Capacity of Water is so high.
We could mix water with other substances to investigate the effect on the Specific Heat Capacity of both substances.
This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.
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