The ‘Sweaty’ Iced Drink
Physics Around Campus
Jack Turner
Physics 102
Spring 2016
If you have ever had a cold drink on a hot day you have probably seen, and felt, the phenomenon that is taking place in the picture above. It seems as though over time, the longer you let your drink sit out the more it “sweats” and the more water there is on the outside of the cup than there was before. It looks like the water practically comes through the cup, or out of thin air, and ends up on the outside of the cup until the drink reaches room temperature. This picture of my Dutch Bros Iced Coffee is exactly that same phenomenon of a “sweating” drink. This photo was taken on a somewhat humid day in mid-April in my apartment
…show more content…
Q is negative in this case because the water going from vapor to liquid loses energy to its surroundings during the phase change. One issue of calculating the energy given off by the condensation reaction for the picture of my iced coffee is that we do not know the mass of the water vapor being converted into water droplets. To make up for this I looked up the average humidity for Spokane in the month of April and found the mass, in grams, of the water vapor per one pound of air based on the humidity and temperature of the air (engineering tool box). From this information we can then calculate the energy given off in our specific phase change of the water vapor onto the cup containing the iced coffee. If the temperature in the room were about 80 degrees Fahrenheit, or 27 degrees Celsius, the calculated mass of the water vapor per pound of air would be about 8.1 grams or 0.0081 kg. The latent heat for condensation is the same as the latent heat for vaporization and it is 22.6 x 10^5 J/kg. Using the equation for the amount of energy given off by a pound of air reacting with the cold surface of the cup causing the phase change is as …show more content…
This energy then can be used in the heat conduction equation to see how much the condensation of the water vapor around the cup of iced coffee changes the temperature of the cup. This equation is Q=(kA∆T)t/L where k is the thermal conductivity of the medium the heat passes through, in this case it is a plastic cup so about 0.3 [J/(s*m*degrees celcius)]. A is the surface area of the cup which in this case is about 1337.7 cm2. Time we can vary but for this example we will say 30 minutes or 1800 seconds. L is length and for the length of the plastic cup we just use the thin distance that he heat had to pass through of about 0.002 meters. Finally with Q as 18,306 Joules we can rearrange to solve for the change in temperature and see how the condensation of water on the surface of the cup effected the temperature of the cup. After computing this it is seen that the change in temperature of the cup was about 0.05 degrees Celsius or about one degree
The molecular weight of caffeine is 194.19 g/mol (3). This is a relatively large weight when compared to other chemical compounds such as water which has a molecular weight of 18.015 g/mol and methanol which has a molecular weight of 32.042 g/mol (3). The density is 1.23 g/mL which means that if pure caffeine were placed in a container of water it would sink to the bottom of the container. The melting point of caffeine is 238°C. Technically caffeine does not boil; but, it does transition directly into a ga...
Per the hypothesis, most of the results in the lab are in accordance with the expected results. It was expected that the subjects drinking caffeine, diet caffeine free soda, and 16 ml/Kg of water would have a higher rate of production than the control group drinking 7.5 ml/Kg of water due to less water being reabsorbed. Results showed an increase in rate of production, most notably in subjects drinking diet caffeine free soda but seemed to decrease towards the end. For the rest of the subjects, the data shows a gradual rise over time with every subject (besides caffeine free) having a higher rate of production than the control group. The subjects drinking caffeine free soda were the only ones to record a lower rate of production than the control group. This could be due to an increase in glucose reabsorption causing water to follow back into the blood stream. The lack of caffeine does not hinder ADH secretion, which will cause an increased permeability to water in the collecting
type of energy is lost or gained, and whether or not a factor that is
heat will stay in the cup and can only escape by rising to the surface
of alcohol and other volatile liquids evaporated could cool an object enough to freeze water.
The purpose of this experiment is to try to find the original temperature of the hot water in the heater using the 60 degrees C thermometer. Use your 60°C thermometer, and any materials available in your laboratory, to determine the temperature of the water in the coffee pot. During this experiment we calculated the original temperature of a heater after it had been cooled down, and we did this by measuring hot, cold, and warm water, with a thermometer that had tape covering 60 degrees and up. When preformed each of these experiments with each temperature of water, plugging them into the equation (Delta)(Ti – hot – Tf) T Hot x Cp x Mass(Cold) = (Delta)(Tf – Ti – Cold) T Cold x Cp x Mass(Hot)(d
There are many reasons for wanting to cool things, but whatever the reason, the Second Law of Thermodynamics dictates that cooling something will take effort (sorry, no spontaneously cool sodas). Different techniques have been developed to address this issue, each having its own limitations and ideal uses.
This is expressed as Δ +ve (delta positive). If the total energy put in is less than the energy created, then the substance warms up (it is exothermic). This is expressed as Δ -ve (delta negative). I will investigate eight different alcohols using an alcohol or spirit burner, to measure the energy change during burning by measuring the change in temperature of some water held in a container.
This warm air entering the cup would increase the temperature of the nitrogen. Temperature is the same as the average kinetic energy, therefore when the average kinetic energy of the nitrogen in this lab came in contact with the air, its molecules began to speed up, increasing the rate of vaporization. This means that some amount of liquid nitrogen vaporized, leaving less in the cup with the water. This would in turn, make the water not reach the lowest temperature that it should have reached because the water and the cup didn’t have as much nitrogen energy to consume. This would make the joules of heat released less, as well as the heat of vaporization values I obtained lower than the theoretical ones. Since the measured heat of vaporization was less than the accepted one, it caused my percent error to be negative. My second unique error has to do with the vaporization of the liquid nitrogen. Once the nitrogen leaves the storage vacuum tank, it begins to boil or vaporize. To accurately calculate the results for this lab, all of the liquid nitrogen we assume, stayed within the cup to cool the
Cold brew: Cold brew is not an iced coffee but it has a different process of brewing coffee with the dripping of cold filtered water into grinds for a long time. The result is a smooth and tasty coffee with an authentic taste of real coffee beans. Cold brewed coffee is not acidic and it is good for upset stomach. You can store this coffee in your fridge for a long
Imagine walking into a small, local coffee shop; what is the first thing that comes to mind? Maybe it’s the pungent aroma of coffee beans, or perhaps it is the sound of quiet jazz music playing softly overhead. Perhaps people even appear in this vision. Who are these fellow coffee dwellers, and what is it that they have to say? The answer to this question happens to be quite inspiring.
When you pour in more cold water, the hot water drains out to make your coffee and the cold water then takes its place to be heated. So, in 3 minutes, you can have a pot of coffee! It doesn 't get any better than that! For years, I had seen Bunn Coffee Makers in convenience stores. I always wished I had one at home, but Bunn Coffee Makers are rather expensive - about $100. Previously, all my coffee makers had been inexpensive, usually $10-$15, and their length of service (usually a year, two if I was lucky) proved that you get what you pay for. As a wedding present, my brother got us a Bunn 10 cup Coffee Maker. I was ecstatic. From the first pot, it was love. "The unique sprayhead design creates the right amount of turbulencet o suspend ground coffee and extract flavor evenly and thoroughly. With most coffee makers, water drips straight through without evenly exposing all coffee granules to the water.", states the Bunn Instruction Manual. The Bunn Coffee Maker has a warming plate under the pot to keep the coffee hot and a light to show that it
On the other hand the nostalgic feeling of coffee in a rainy or winter morning may bring you a nostalgic feeling of romanticism. If you have the campus experience, you can’t forget some exciting moments with a cup of coffee when you were with your university friends who still not beside you. You can just recall the past with the smoky flavor of a cup of coffee. So coffee can always bring us the fresh
The relationship between water and steam can be found in the temperature – entropy diagram. It can be realised from the T-S diagram, that the condition of a steam-water mixture is somewhere between that of saturated water and that of saturated steam. If any change in pressure or temperature of the water-steam mixture can lead the mixture to be saturated water or saturated steam. Obviously, when there is an amount of moisture present in steam, it will contribute to the energy consumed or heat utilised which increases the temperature of the moisture to that of the steam. (Babcock & Wilcox Co., 2007)
A man by the name of Sadi Nicholas Leonard Carnot started experimenting with the idea of hot and cold in the early 19th century. He released a book in 1824 that shared his observations in attempting to find the amount of work per one kilogram of steam. He found that temperature was equivalent to dropping water from different heights. In his experiments he found that water released from a greater height could produc...