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Calorimetry Lab - Data Collection and Processing

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Calorimetry Lab

Data Collection and Processing

The purpose of this lab is to determine the identity of an unknown metal using an experimentally-derived specific heat.

Trial 1

Trial 2

Mass of Metal

49.239 ± .001g

40.872 ± .001g

Mass of Water

24.440 ± .001g

24.191± .001g

Initial Temp of Hot Metal

102 ± .5oC

102 ± .5oC

Initial Temp of Water

22 ± .5oC

23 ± .5oC

Temp of Mixture

34 ± .5oC

34 ± .5oC

Temp Change of Metal

68 ± .5oC

68 ± .5oC

Temp Change of Water

12 ± .5oC

11 ± .5oC

 

To calculate the heat energy gained by the water, use q=mcΔT.

Trial 1: (24.440 ± .001g)(4.184 J/goC)(12 ± .5oC)=1227 ± 51J

Trial 2: (24.191± .001g)(4.184 J/goC)(11 ± .5oC)=1113 ± 51J

To calculate the specific heat of the metal, set q of the water equal to mcΔT of the metal.

Trial 1: 1227 ± 51J= (49.239 ± .001g)(c=specific heat)(68 ± .5oC)                c=.366 ± .018 J/goC

Trial 2: 1113 ± 51J= (40.872 ± .001g)(c=specific heat)(68 ± .5oC)                c=.401 ± .021 J/goC

The average specific heat is: .384 ± .020 J/goC

On the chart of specific heats given to us, the closest value was that of copper, .385 J/goC.

 The percent error is therefore:

.385 J/goC - .384 ± .020 J/goC

.385 J/goC

= .260 ± .014 %

Conclusion and Evaluation

        From the experimental data and calculations, the specific heat of .384 ± .020 J/goC led us to believe the identity of the unknown metal was copper. The percent error was very low, a mere .260 ± .014 %. However, this was only achieved after the averaging of the data from two trials. To achieve better accuracy and precision of the experiments, many methods can be taken to avoid unnecessary discrepancies. Firstly, our calorimeter was just two Styrofoam cups stacked upon each other. This leaves a lot of room for error because much heat can be lost to both the surrounding and the calorimeter itself, yielding inaccurate results. A more technologically advanced calorimeter can limit the amount of energy loss. Additionally, temperature readings can be improved by using more accurate thermometers, as we only had normal glass thermometers. The class period was only 1 hour, unlike the AP’s class of an hour and a half. If we had more time, we could’ve performed more trials and decreased the effect of random error in our experiments.

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