Materials:
- Measuring cup
- Ice cube
- Water
- Thermometer
Procedure:
- Prepare 1 cup of room temperature water(22°C)(Measure with thermometer)
- Take an ice cube out of freezer(Record temperature)
- Put ice cube in water; wait till the solution is all water.
- Record temperature of water.
- Repeat steps 1-4 with water temperatures of 30°C,and 38°C
- Record mass of water and ice cube.
Collecting Raw Data
Trial 1(Water 22°C) Trial 2(Water 30°C) Trial 3(Water 38°C)
Processing Raw Data:
Calculations for Latent Heat of Fusion at 22°C(all temperatures converted to °K)
Qwater=mwcw(295°K – 290.8°K)
Qice=miceL + micecw(290.8°K – 273°K) + miceCice(273°K - 263°K)
mwcw(295°K – 290.8°K) = miceL + micecw(290.8°K – 273°K) + miceCice(273°K - 263°K)
We know that: Cwater = 4.19 kJ/kG°K,
Cice = 2.11 kJ/kG°K
4.15 = 0.01L +0.96
3.19 = 0.01L , L = 319 kJ/kg
Latent Heat: 319 kJ/kg
Presenting Data:
Table #1: Latent Heat at Different Temperatures
Conclusion:
In the preceding lab, it is noticeable that water temperature does not affect the latent heat of fusion. Therefore the lab is a success and has proven that latent heat is indeed a constant. The latent heat of fusion for the three trials was 319 ± 0.1 kJ/kg, which is only 15 away from the actual latent heat of fusion of 334 kJ/kg.
Evaluating:
When measuring the temperatures for the ice and the water they might not be accurate due to the thermometer and human reading error. This affected the final latent heat of fusion. Because the ice cube was not immediately put into the water, it might have gained some heat causing a decrease in accuracy in the latent heat. When heating the water temperatures to the desired amounts human error could have cause poor accuracy and slow thermometer readings could cause the measurements to be less precise.
Improving:
An electronic and more accurate thermometer could be used. The temperature of the ice cube could be measured inside the freezer to prevent it from heating, and then immediately placed into the cup of water. When heating the water to the desired temperature, an accurate device and thermometer should be used to get the water to exactly the necessary temperature.
