NOTE: Free essay sample provided on this page should be used for references or sample purposes only. The sample essay is available to anyone, so any direct quoting without mentioning the source will be considered plagiarism by schools, colleges and universities that use plagiarism detection software. To get a completely brand-new, plagiarism-free essay, please use our essay writing service.
One click instant price quote
Experiments to Determine the Cooling Rate of Coffee, when Milk should be Added and what Container should be Used The aim of the first experiment was to find out and record the cooling rate of coffee under three different conditions and thus showing when milk should be added assuming you have a phone call. The three different conditions were chosen because these were the most likely situations encounter by someone who is making a cup of coffee. We used Tain instruments to accurately calculate the temperatures in the three beakers chosen and we then recorded these results and used them for this report. The purpose of the experiment was to find out whether it is best to pour milk in a cup then take a phone call, or pour milk into your cup of coffee after a phone call. We also had an extra large beaker to examine whether a larger cup caused the coffee to lose or retain heat. I wasn't really sure what would happen and therefor I couldn't predict much.
I did however, believe that the beaker (substituted cup) that was larger than the rest would cool the quickest. This would be logical as the larger beaker allows the water more surface area that evaporates. The aim of the second experiment was to take the temperature of coffee in different containers over several minutes to discover which containers retained and lost the heat. The five containers chosen were the most likely one used by the average person making a cup of coffee. Tain instruments were used again to calculate the temperature of coffee in polystyrene, ceramic, plastic, insulated plastic and glass containers.
The purpose of the experiment was to decide which container would best retain the heat of the coffee and keep it as hot as possible for the longest amount of time. The only prediction I could make is that one of the worst heat retainers would be glass. This is because it takes a long time to help up and then the glass becomes a good conductor of heat and it becomes hot. As the glass is hot this means convection is very high and the glass would lose a lot of heat allowing the coffee to cool quickly.
Materials: Kettle Three Tain Sealed Probes Two identical small beakers One wide beaker Cold Milk Tain Controller Box & Adapter Instant Coffee Spatula Laptop Computer Method: To start off the first experiment Win Tec was opened, the experiment The Cooling Cup of Coffee was opened up and we connected to Tain controller box. Three beakers were collected, 11 / 2 spatula fills of instant coffee were placed in each beaker and then one sensor was then put in each beaker. The kettle was turned on to prepare the hot water and when it was ready, the water was quickly poured into each beaker with approximately 75 mls in each. A splash of milk was then added to the first beaker and it was stirred with the probe. The temperatures recordings then commenced using the Tain program. After 12 minutes, a small splash of cold milk was added to the two remaining beakers and the experiment continued until 15 minutes was over.
The coffee was disposed of down the drain and then we saved the results and constructed a table. To start the second experiment, a new experiment was set up in Win Tec that supported the use of five sealed probes. Five chosen containers were collected and these were a ceramic, glass, plastic, insulated plastic and polystyrene containers. Then 11 / 2 spatula fills of coffee were placed in the three containers.
The kettle was boiled and 110 mls of boiling hot water was poured into the containers. No milk needed to be added so we commenced the temperature recordings and continued these results until we came up to the 8 th minute. The experiment was then stopped, the coffee was poured down the drain and the results were saved in a table form. Results: The table below shows the results from the first experiment. I decided to show the results in a table because it was the easiest form to interpret. Time (min) Temperature of Small Beaker.
Milk added before (C) Temperature of Small Beaker. Milk added after (C) Temperature of Large Beaker. Milk added after (C) Start of Experiment 65. 2 72. 6 69. 7 1 65. 3 70. 8 65. 6 2 65. 6 68. 1 63. 9 3 63. 1 66. 0 60. 6 4 61. 0 63. 5 58. 1 5 58. 9 61. 0 55. 6 6 56. 8 58. 9 53. 5 7 55. 2 56. 8 51. 9 8 53. 9 55. 6 50. 2 9 51. 9 53. 9 48. 5 10 51. 0 52. 3 46. 9 11 49. 4 50. 6 45. 6 12 Milk Added to Beakers 2 + 3 48. 5 49. 8 44. 8 13 47. 3 48. 5 43. 5 14 45. 6 46. 9 41. 9 15 44. 8 46. 5 40. 6 This table shows the rate of coolness that the three samples of coffee experienced. You are able to see how the beakers that were in different situations cooled compared to the others. As the time advances, you can also see how the different beakers cooled and what their final temperature was before the experiment was stopped.
This table shows the results from the second experiment: Time (min) Temp. of Polystyrene Container (C) Temp. of Ceramic Container (C) Temp. of Insulated Plastic Container (C) Temp. of Glass Container (C) Temp.
of Plastic Container (C) Start of Experiment 79. 3 67. 2 73. 5 60. 1 43. 1 1 77. 2 63. 9 74. 7 64. 7 74. 7 2 74. 7 61. 8 71. 8 61. 8 72. 2 3 72. 2 60. 2 68. 9 60. 2 69. 3 4 69. 7 58. 5 66. 8 58. 5 66. 4 5 67. 2 56. 8 64. 7 57. 3 63. 9 6 65. 6 55. 6 62. 7 56. 0 61. 8 7 63. 5 53. 9 61. 0 54. 8 60. 2 8 62. 2 52. 3 59. 3 53. 5 58. 1 This table allows you to view the rate of coolness between the five different containers that the coffee was poured into. You are able to view the container that retains the heat most by studying the final temperature of all five containers. It was clear that polystyrene and insulated plastic (had an air gap between two layers) were the best heat retaining containers. Plastic was average and both ceramic and glass were poor heat retainers. Conclusion: Both the experiments were carried out very successfully and the results recording was fine. Looking at the results from experiment one, they show that it is a benefit to have a tall but narrow container and to add the milk after a phone call.
The tall but narrow container reduces the surface area of the coffee, reducing evaporation and therefor retaining the heat longer. The results do not contradict with Newton's Law of Cooling which basically states a hotter object cools quicker than a cooler object which is logical as evaporation controls most of the heat loss. The results however, show that there is only a slight advantage to add the milk afterwards and not before making the phone call. In the second experiment, it was quite surprising to see which containers are better to use than others if you still want a hot coffee after some time away, busy on the phone.
From the second experiment it is now clear why you get given a polystyrene cup when you are on long trips. This is because the polystyrene is a low conductor of heat and so the actual cup doesn't get hot. The convection of the polystyrene is also low and this means the cool air around the cup does not cool the coffee and the cups structure stops your hands getting burnt... The table on the next page shows the approximate conduction, convection and radiation levels of the various containers. Cup Conduction Radiation Convection Polystyrene Low Same Low Glass Highest Same High Ceramic Middle Same Middle Plastic High Same Middle Insulated Plastic Low Same Low From looking at this table you are able to tell which containers would be the best and worst at retaining heat and also show you that radiation is not an issue in this experiment.
For heat to be lost through conduction, the hot liquid needs to be touching the glass or the plastic while convection needs cool air to be circulating around the object. The only error I found in these results is that of the second experiment with the starting reading for the plastic container as it read 43. 1 C. This was obviously a miscalculation or delay by the Tain equipment and the probe settled down on the next reading. There is also a good explanation to why the first beaker in the first experiment, that had the milk poured in first, was rating in temperature during the first 3 minutes. This is likely to be due to thermal layers in the hot coffee water when the milk is first poured in. When this beaker was stirred the temperature could have risen as hotter coffee was merging with the same layer the probe was testing.
The only way to confirm this explanation is to complete an experiment where there are two beakers of coffee and they have milk poured into them however only one of them get stirred. Overall there would have been no problems with the volumes as I made sure all of the beakers had the same amount of coffee as the other beakers in that experiment. A good experiment to try would be one where there are two beakers of coffee filled to the brim. Then place cling wrap over one beaker, don't put any on the other beaker and then record their temperature to see how evaporation plays a part with heat loss.
Free research essays on topics related to: surface area, hot water, phone call, heat loss, cup of coffee
Research essay sample on Cooling Rate Of Coffee
