Specific Heat Capacity Report PDF

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Specific Heat Capacity lab report...

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Faculty of ACES Department of Engineering and Mathematics Mechanical Engineering Laboratory (Sheaf – 4028)

Measurement of the Specific Heat Capacity of a Metal Specimen Sheffield Hallam University Department of Engineering and Mathematics

For the attention of:

Rohan Tittagala

Report author:

Ben Cresswell

Report author ID:

B5045052

Module name & code: Engineering Principles (16-4019-00S-A-20156) Course name:

Electronic Engineering

Date:

17/12/2015

Abstract

This report is an experiment to determine the specific heat capacity of an unknown material. By identifying the material we can compare the result to the table of actual specific heat capacities of known materials to determine which material was used in the experiment. The purpose of this experiment was to find the specific heat capacity of the material by measuring the temperature change when the metal was placed inside the calorimeter. The specific heat capacity of sample 1 was 0.116 kJkg-1 K-1. The specific heat capacity of sample 2 was 0.296 kJkg-1 K-1. Finally the specific heat capacity of sample 3 was 0.773 kJkg-1 K-1.

Nomenclature

g = grams

kg = kilograms J – Joules K- Kelvin ms

= mass of sample (kg)

m c = mass of calorimeter (kg) m w = mass of water in the calorimeter (kg)

cs = specific heat capacity of sample (J kg-1 K-1) cw = specific heat capacity of water (J kg-1 K-1) T initial sample = initial temperature of the sample ℃ T final sample = final temperature of the sample ℃ T initial water = initial temperature of the water ℃ T final water = final temperature of the water ℃

Contents Abstract..........................................................................................................................i Nomenclature................................................................................................................ii 1

Introduction............................................................................................................2 1.1

2

3

4

Aim ..................................................................................................................

Background Theory...............................................................................................5 2.1

.........................................................................................................................5

2.2

.........................................................................................................................6

Procedure..............................................................................................................8 3.1

Equipment.......................................................................................................8

3.2

Procedure........................................................................................................8

Results.................................................................................................................10

5

Discussion...........................................................................................................12

6

Conclusions.........................................................................................................13

7

References..........................................................................................................14

1

1 Introduction The specific heat capacity, cp of a material is the amount of heat energy required to heat one kilogram of that material by 1 ℃ or 1K. It is a physical property that varies from one material to another. A calorimeter is a container, usually well insulated, which allows measurement of temperature changes of its contents to be measured. If a hot specimen is placed in cooler water inside a calorimeter, the temperature of the specimen will fall, while that of the water will rise as the heat energy is transferred from one to the other. If there are no heat losses from the calorimeter, the temperature of the system will reach equilibrium i.e. the temperature of the specimen, water and calorimeter will be the same. 1.1

Aim of the Experiment

To measure the specific heat capacity of a metal sample using a calorimeter. 2 Background Theory If the heat losses from the calorimeter are small, this heat transfer can be expressed as: Heat energy lost by the specimen = Heat energy gained by the water. Or m s c ps ( T initial sample -

where

T final sample ) =

m w c pw ( T final water (1)

-

T initial water )………..

m s = mass of sample (kg) m c = mass of calorimeter (kg) m w = mass of water in the calorimeter (kg) cs = specific heat capacity of sample (J kg-1 K-1) cw = specific heat capacity of water (J kg-1 K-1) T initial specimen = initial temperature of the sample ℃ T final specimen = final temperature of the sample ℃ T initial water = initial temperature of the water ℃ T final water = final temperature of the water ℃

and equation (1) becomes m s c s ∆ T s (2)

=

mw c w ∆ T w

where ∆ T s = ( T initial sample - T final sample ) and T initial water )

………………………………..

∆ T w = ( T final water -

3 Procedure

This will be all the equipment you will need in the experiment.

First of all the mass of each metal is needed, therefore you will need a pair of scales to measure and record this. When the mass of the metal is recorded use the metal hook to submerge the metal into the beaker of water and heat the water up to boiling point. Measure and record the temperature of the water using a thermometer or digital probe. The mass of the empty calorimeter and the amount of room temperature water added is then needed, this can be found by using the scales. Record these masses down. Once theses masses have been recorded add the room temperature water to the calorimeter and take out the stirrer and lid using the metal hook.

Again using the metal hook, being very careful, quickly place the metal from the boiling water inside the beaker into the calorimeter and quickly replace the lid, stirrer and thermometer to observe the temperature rise of the water. Stirring continually, be sure to pay full attention to the small temperature rise of the water, and record the steady maximum in which the temperature appears to reach. Once you have recorded the maximum temperature, empty the contents inside the calorimeter and repeat the experiment for a different metal type.

4 Results

Mass of Sample 1 = 105.31g = 0.10531kg Mass of Sample 2 = 85.84g = 0.08584kg Mass of Sample 3 = 29.70g = 0.02970kg Mass of Empty Calorimeter = 963.70g = 0.96370kg Mass of Calorimeter with water added = 1061g = 1.061kg Mass of water added = 1.061kg – 0.96370kg = 0.0973kg Initial Temperature of sample 1 = 23.6 ℃ +/- 0.5 ℃

Initial Temperature of sample 2 = 26.1 ℃ +/- 0.5 ℃ Initial Temperature of sample 3 = 25.7 ℃ +/- 0.5 ℃ Final Temperature of sample 1 = 96.7 ℃

+/- 0.5 ℃

Final Temperature of sample 2 = 96.7 ℃

+/- 0.5 ℃

Final Temperature of sample 3 = 96.7 ℃

+/- 0.5 ℃

Initial Temperature of water sample 1 = 21.4 ℃

+/- 0.5 ℃

Initial Temperature of water sample 2 = 21.7 ℃

+/- 0.5 ℃

Initial Temperature of water sample 3 = 21.7 ℃

+/- 0.5 ℃

Final Temperature of water sample 1 = 23.6 ℃

+/- 0.5 ℃

Final Temperature of water sample 2 = 26.1 ℃

+/- 0.5 ℃

Final Temperature of water sample 3 = 25.7 ℃ +/- 0.5 ℃ ∆ T w = (������ �����temp - �������� �����temp )

∆Ts

= (������ sample temp - �������� sample temp)

As the calorimeter has such a small amount of heat loss we can assume Total heat lost by the metal block = Total heat gained by water ms c s ∆ T s

= mw cw ∆ T w

To find the specific heat capacity of the sample, equation can be rearranged to: cs

=( m w c w ∆ T w )/( m s ∆ T s )

Specific Heat Capacity of sample 1: cs

= (0.0973*4.187*2.2)/(0.10531*73.1) = 0.116 kJkg-1 K-1

Specific Heat Capacity of sample 2: cs

= (0.0973*4.187*4.4)/(0.08584*70.6) = 0.296 kJkg-1 K-1

Specific Heat Capacity of sample 3:

cs

= (0.0973*4.187*4)/(0.02970*71) = 0.773 kJkg-1 K-1

5 Discussion

The significance of this experiment is to determine the material of the sample by finding its specific heat capacity. By find the specific heat capacity of the material it allows us to compare it to a table of materials with similar specific heat capacities to determine what metal it actually is. There are many limitations to this experiment for example the transferring of the metal block out of the hot water into the calorimeter is limiting, as during this transfer there will be a significant loss of heat energy to the surroundings which could impact the results. Another limitation of this experiment is the parallax error in reading the exact temperature off the thermometer. This error could be controlled by using a digital thermometer which will give reading to a more accurate degree, reducing percentage error in measurements and in calculations. Specific heat capacity has many uses in everyday life. For example in engines the different parts expand and contract due to the fluctuations of the heat in the engine. Therefore engine parts must be of the same specific heat capacity because if one part heats up and expands/contracts faster than another part this will cause cracking. Another common use of specific heat capacity is a kettle. The heating element inside the kettle has a low specific heat capacity to heat the water up but the kettle itself must have a high specific capacity to prevent somebody from burning themselves. This specific heat capacity experiment is hard to control due to the metal object being exposed to the air before it is submerged in the calorimeter. This makes it hard to make a very precise decision on what material the metal is. In fully controlled conditions where there is no heat energy lost to the surrounding the actual specific heat capacity can be found and this would be the specific heat capacity value for that material.

6

Conclusions

In the experiment above, after competing all calculations we could identify each material by its specific heat capacity. Sample 1 had a specific heat capacity of 0.116

kJkg-1 K-1, therefore the material would be lead as it is known that lead has an actual specific heat capacity of 0.129 kJkg-1 K-1. Sample 2 had a specific heat capacity of 0.296 which would suggest the material of sample 2 would be germanium. Sample 3 had a specific heat capacity of 0.776 kJkg-1 K-1 which would be classed as potassium due to the table. I believe there is a large source of error in the above experiment and due to this factor I cannot give an accurate interpretation of what materials were used based on the results of the experiment. Repeating this experiment would give better results as averages would be able to be taken and a more precise decision for the sample material would be achieved.

7

References



Scribd (2015). Real World Context of Specific Heat Capacity.

http://www.scribd.com/doc/139539080/Real-World-Context-ofAvailable at: Specific-Heat-Capacity#scribd [Accessed 20 Dec. 2015].



Tutorvista.com, (2015). Specific Heat of Metals Chart | Specific Heat Chart |

Available at: http://www.tutorvista.com/physics/specific-heat-of-metals-chart [Accessed 20 Dec. 2015].

Assessment Grid

The Assessment Grid shows how you will be awarded marks for the respective sections of the report.

Final Marks Sheet

You will be awarded marks for this lab according to the following scheme. (Please add this page to your report at the end) ________________________________________________________ Lab Book (10%) Recording of work, engagement in the task, punctuality

-

/10

(0 or 5 or 10 marks will be recorded by tutor according to their Personal judgement)

_______________________________________________________ Report Introduction / Objectives / Theory (20%)

-

(No

Procedure (10%)

-

/10

Results (20%)

-

/20

Discussion and Conclusions (30%)

-

/30

Presentation (20%)

-

/20

Mark) (This has been written for you. Please include the given text)

(Including Abstract, Nomenclature, Contents page, References And correct use of English)

________________________________________________________

Total

-

/90

Percentage Mark

-

%

________________________________________________________ Note: The final mark, awarded out of a total of 90 (as above), is converted to a percentage mark for the write-up Lab. The % mark will appear under My Grades for this lab report....