Latent Heat And Specific Heat Capacity Assignment
Specific Heat Capacity
AIM To identify solids by measurement of specific heats.
The specific heat capacity c of a substance is the amount of heat, Q which must be added to per unit mass the substance to raise its temperature by 1 K.
|c =||Q||equation 7|
The specific heat of a substance may be found by the “method of mixtures”. A mass mm of the material is heated to a temperature TW contained in a calorimeter with stirrer (of same material) of mass mC and specific heat cC. The complete system is allowed to come to a final temperature Tf.
Now provided no heat is lost to the surroundings then the total heat for the system is
mm cm(T f− Tm)+ mwcw(T f− Tw)+ mc cc(T f− Tc)=0 equation 8
Solving this equation for cm we have an expression for the specific heat capacity of the material
|cm||(mccc+mwcw )(Tf||− Tw)|
specific heat of water, CW = 4.18 x 103 J kg-1 K-1 specific heat of copper, CC = 0.38 x 103 J kg-1 K-1
Note NO error calculations are required in this part but ensure that a suitable number of significant figures are used.
- Add enough tap water to the calorimeter so as to just cover the thermometer bulb (or temperature sensor) and weigh it. Determine the mass of water using the calorimeter mass determined in part A.
- Record the temperature of calorimeter and water.
- Weigh the metals provided and immerse them in continuously boiling water.
- Quickly and carefully use tongs to transfer the first sample of heated metal to the calorimeter.
- Stir the water and record the resulting maximum temperature.
- Repeat steps 1 to 5 for the other metal samples using fresh water each time, and tabulate results.
- Calculate cm for each of the pieces of metal and determine from the table below the type of metal.
TABLE OF SPECIFIC HEATS
|Material||c (J kg-1 K-1)|
Lab proforma and answers:
H8 – LATENT HEAT AND SPECIFIC HEAT CAPACITY
Student Name __________________________________________________________
|Student Number ________________________||Date___ / ___ / _______|
|1.0||Clearly entered data values|
|1.0||Correct units and multipliers in column/row headings|
|1.0||Data quoted to an appropriate number of significant figures|
|____ / 3 marks|
|1.0||Informative graph titles|
|1.0||Axes clearly labelled|
|1.0||Correct axis units and multipliers stated|
|1.0||Data plotted correctly|
|1.0||Appropriate lines of best fit drawn|
|1.0_Appropriate uncertainty lines drawn|
|____ / 6 marks|
|1.0||Calculations clearly set out|
|1.0||Correct formulae or relationships used|
|1.0||Values consistent with data substituted correctly into formulae|
|1.0||Realistic uncertainty values stated or calculated|
|1.0||Uncertainty calculations clearly shown|
____ / 5 marks
2.0 Technique efficient and accurate
3.0 Answers to questions show understanding of concepts
1.0 Conclusions consistent with results and aims
____ / 6 marks
Total = _________ / 20 Demonstrator Sign: ____________________
H8 – LATENT HEAT AND SPECIFIC HEAT CAPACITY
Part B Specific Heat Capacity
- Record your measurements in the table below. Use published data to identify each material in the final row.
|Mass of Wooden Lid (g)||30.9||30.9||30.9|
|Mass of Calorimeter, stirrer and lid (g)||139.7||139.7||139.7|
|Mass of Calorimeter and stirrer (g)||80.5||80.5||80.5|
|Mass of Calorimeter, stirrer, lid and water (g)||249.0||242.7||242.2|
|Mass of Water (g)||109.5||102.9||102.5|
|Temperature of the Calorimeter and water (oC)||22.3||22.1||22.1|
|Mass of material (g)||8.6||33.3||30.7|
|Max Temp of water and calorimeter (oC)||23.5||24.3||23.9|
|Specific Heat capacity of the material (JKg-1 K-1)||891||402||354|
|(show calculations below)|
|Show sample calculations for specific heat capacity (for one material) here|
Specific heat of water, CW = 4180 J kg-1 K-1
Specific heat of copper, CC = 380 J kg-1 K-1
Mass of Calorimeter, stirrer and lid, MC = 80.5 g = 0.0805 Kg
Mass of Water, MW =109.5 g = 0.1095 Kg
Max Temp of water and calorimeter, TF = 23.5 oC
Temp of the calorimeter and water, TW = 22.3 oC
Mass of material, MM = 8.6 g = 0.0086 Kg
Temp of material, TM = 100 oC
Specific heat capacity of the material, CM= ?
JKg-1 K-1 Aluminum
- Your answers to any questions asked in the experimental instructions
- Direct comparison of your final result(s) with accepted or published value(s) or trends
- Identification of factors limiting reliability of measurements and results and any measures taken to increase this reliability.