Chemistry Ia - Measuring Heat Capacity of a Cup

Topics: Thermodynamics, Temperature, Water Pages: 7 (1766 words) Published: September 11, 2011
IB Chemistry Assessment

Sami Nidal Mroue
Year 12 JRF

Heat Capacity of a foam cup
This is an experiment to determine the heat capacity of my foam (styrophome) cup I would be using for other experiments during the school year. To do this the temperature of a known mass of cold water was poured into the cup and the same amount of water heated and had its temperature noted. The hot water was poured into the cup and the new temperature reading noted. Then the equation Q = m.c.∆T is applied to find the heat capacity of the cup. Aim

To determine the heat capacity of a styrophome cup (calorimeter). Independent Variable: Temperature change for the cold and hot water. Dependent Variable: Heat capacity of the cup
Controlled Variables: Mass of water used (25ml = 25g)
Heat Capacity of water (constant)

It’s difficult to predict what the heat capacity is going to be but the heat capacity that is to be found has to be over 0ºC. The answer definitely cannot be in the negative because that would mean that the cup is the one giving out heat and vice versa and has to be over 0ºC because it is gaining heat.

Apply a mass of 25g of cold water to the cup and note down its temperature reading by sticking a thermometer into the cup (the cup could be made more stable and better insulated by fitting it into a beaker). The mass of the water is measured by filling a measuring cylinder with 25ml of water (1ml=1g) then heat an equal amount of water to a temperature of approximately 50ºC in a beaker sitting on a tripod stand with a Bunsen burner and pour it over the cold water, stir with a stirring rod and note the temperature change. A cloth could be used to lift the hot beaker. Repeat the experiment three times or to obtain reliable and consistent results. After recording the data, for each experiment find the difference in temperature between the mixed and cold water temperatures and also for the mixed and the hot water temperatures. Whenever taking temperatures a thermometer has to obviously be used and inserted into the liquid. Now the equation Q = m.c.∆T can be applied after expanding into∆Th =∆Tc + mcup.ccup.∆Tcup. N.B. the heat capacity of the cup = mcup.ccup

Apparatus used thermometer
A styrophome (foam) cup measuring cylinder thermometer A thermometer (-10 to 100ºC)
Beakers (50ml+) cuphot water
Measuring cylinders (25ml ±1ml)wire gauze
A Bunsen burner water Bunsen burner A tripod stand
Wire gauze beakerTripod stand Matches
A cloth (to hold the hot beaker)
Waterstirring rod
Stirring rod

Controlling the variables

Independent variables:
The temperature of the cold water I used was the normal temperature measured in the room temperature, the temperature could be dropped by using cold refrigerator water or adding an ice block until the temperature drops to the desired marked. The temperature of the hot water I used was 50ºC for all experiments. I put 25ml of water into a beaker and heated it with the thermometer submerged. When the temperature got to 50ºC I removed the beaker of the tripod stand. The temperature would rise a little over the 50ºC mark and then I allowed it to cool until it was 50ºC again before I poured the water into the cup.

Controlled variables:
Mass of the water used for the cold and hotter water was 25g. The total mass of the water in the cup was 50g. The water mass did not have to be weighed for 1g of water equal 1ml of water. A 25ml measuring cylinder was used for this. A 25ml of water would be filled to the mark and poured into the cup and another...
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