Sources:
- OCR Gateway GCSE Science Student Book
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Hypothesis
The greater the amount of ice that melts the bigger the temperature drop of the water
This is because when more ice melts more energy is taken from the water
Apparatus
- 5 identical beakers which are made of the same materials
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Thermometers with a suitable range; -10oC to 100oC
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Measuring with volume above 200cm3
- Top-pan balance reading with up to 35g
- Ice (crushed), not straight form the freezer
- Suitable insulating material
- Means of removing water e.g. paper towels
- Stopwatch to measure time in minutes and seconds
Method
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Pour 200cm3 of water into 4 same sized beakers of the same materials. This is so the materials does not affect the in temperature
- I am going to measure the temperature of the water. I am going to make sure the temperature is the same to make it a fair test. I am going to leave the water to become room temperature for about 5 minutes
- I am going to add 15g of ice to Beaker 1, 25g to Beaker 2, 25g to Beaker 3 and the fourth Beaker will have no ice. The fourth beaker will set the benchmarks. The amount of ice is the independent variable. I will measure the ices mass by using the top-pan balance. I used these certain amount of mass so I have a big range of data and will make a better comparison.
- I will then measure the temperature of the beakers every minute for five minutes.
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Then I will put all my results into a table and then into a line graph so I can make easy comparisons
Hazards, the risks and how to reduce the risks
Results Table
- Describe any patterns or trends in your results. Comment on any unexpected results.
After analysing my result I have found some trends in the data. I also saw some anomalies that came up in the experiment.
The most obvious trend is in the line graph and the temperature drop. The more mass of ice I put into the beaker to cool the drink, the faster the temperature dropped. For example, in beaker one, which had 5g of ice, in minute two averaged out at 18.3oC, but beaker 4, which had 35g of ice, averaged out at 14.3oC. Also, in the 3rd minute the temperatures averaged out at 18oC and 12.3oC.
One unexpected result was in beaker 4, were the temperature after one minute averaged out at 17.30C, which is higher than beaker 3 as it was 170C. Another anomaly is that beaker 1 and 2 both averaged out at 19oC, which is unexpected as beaker 2 had more ice, so should have had a lower temperature.
- Compare results of your own investigation (Part 2) with the data from other groups within your class and any data collected in Part 1.
Comment on any similarities and differences. Suggest and explain possible reasons for any differences.
There are a few similarities and differences between our results. On similarity is that the more ice they added the faster the temperature dropped. For example, beaker one, which had 15g of ice, after 3 minutes had dropped to 150C, while beaker four , which had 30g of ice, in the same amount of time dropped to 14g.
One difference is that they did the test for 5 minutes. Another difference is that their temperature range was different from ours. This is probably because their starting temperature was different to ours. Also, probably because they did over three days while, we did it over 1 day. This would explain the sharp drop in temperature after one minute in beaker 5, which had 35g of ice.
- Evaluate your results, the method you used and how well you managed the risks.
Most of the results from the experiment were predictable except for some anomalies; one being the fact that beaker 4 was warmer in minute one compared to beaker 3 which had less ice, another anomaly is that beaker 1 and 2 had the same average temperature after one minute.
A few things could have gone wrong with my method. For example, I could have got the reading wrong from the thermometer. To prevent this problem in the future I would have used a digital thermometer. Another problem with my method was that I might have got the mass of the ice wrong and also the ice could have melted in my hand when carrying it to the beaker. One way to remove this problem is by having the ice next to the beaker and also to wear gloves to prevent my body heat from melting the ice.
We managed most of the risks really well. one way we did this is by keeping the water and ice away from the plugs, sockets and tried to not drop it on to the floor. We also tried to not handle the ice for a long time as that would have given us frostbites. Also we kept the top-pan balance away from the edge of the table so it would not fall on the floor and injure someone.
- Do your results from Part 2 support the hypothesis suggested by Charlie’s friend? Explain your answer.
Yes, our results from part 2 do support Charlie’s friend. This is because the hypothesis suggested that the more ice that is used the bigger the temperature drop. Our results prove this as shown by the chart and our results table. The more ice we added the higher the temperature dropped. This is because the more ice we added the more energy was required to melt the ice, reducing the temperature of the ice. The less ice we added the less the temperature dropped as less energy was required to melt the ice.
- Is it possible to use the equations below to predict the temperature drop of the water when a chosen amount of ice is added to it?
Will the actual temperature drop, measured in your experiment, be equal to the predicted value? Use relevant scientific explanations in your answer.
Use the results of your experiment, appropriate calculations and your research (Part 1) to provide evidence to support your answer.
Yes, it is possible to predict the temperature of the water by using these equations.
The temperature drop should be equal to the predicted value. This is because the amount of energy used to change the state of the ice is related to the amount of energy lost by the water, thus changing the temperature. So the more ice we add, the more energy is taken from the water to change the state of the ice, therefore reducing the temperature of the water and vice-versa.
We used 200cm3 of water which is 200g and was at 21oC. In the first minute in beaker one, which had 5g of ice, the temperature dropped to 19oC, so the energy released by the water was 200(g)x4.181(j/kg, specific heat capacity of water)x2(oC) which is 1671.2j of energy. 5g of ice needs 1670j of energy to change the temperature of ice as 5(g) x334(j/g, specific latent heat of water) is 1670j
