Physics Lab - Latent Heat of Fusion of Ice

Aim :To measure The Latent Heat of Fusion of Ice.

Introduction – Latent heat of fusion of ice is the energy required for ice to change state from solid to liquid water or vice versa. The latent heat of fusion of ice is estimated to be 333 Joules/gram. In the experiment, the latent heat of fusion of ice would be found using the below mentioned “Method”.

Apparatus:1. A few Ice Cubes 2. 100cm3 of water 3. A Calorimeter 4. A digital Thermometer 5. A Measuring Cylinder (marked till 100cm 3) 6. A digital balance

Method:1. Take an ice cube in a beaker & measure the mass. 2. Measure 50cm3 water in the measuring cylinder. (50cm3 in this case). 3. Measure & note down the initial temperatures of the two (ice & water) separately using the digital thermometer. 4. Mix the two in the copper beaker of the calorimeter. 5. Wait for the equilibrium temperature, where the temperature is stable. 6. Note down the final, stable temperature. 1

Variables:1. Independent :– The Ice Cube used – it’s mass 2. Dependent :– Latent Heat of Fusion of Ice & the equilibrium temperature 3. Constant :– Specific Heat Capacity of ice & water - Mass & Temperature of water - The Apparatus used - The surrounding temperature & other conditions - The copper calorimeter – it’s mass

Safe Test:1. The digital balance should be used carefully. 2. The display of the digital thermometer should not come in contact with water or ice.

Fair Test:1. The calorimeter should be insulated with sponge or a similar insulator. 2. The sensor of the digital thermometer should not be touching the walls or the base of the beaker while measuring the temperature of water. 3. The mass of the Ice cube should be measured in a beaker & not directly on the balance. 4.

The mass of water should be measured separately as 50ml of water might not have a mass of 50g due to varying density of the tap water used.

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Processed Data:-

Table showing the processed data Mass (g) Water Ice Equilibrium

Temperature (oC) 27.6 05.4 07.4

50.0 13.2 -

Temperature change (oC) 27.6 – 7.4 = 20.2 ∆T1 = 5.4 ∆T2 = 7.4

Known Values & definitions Specific heat capacity of water = Cw= 4.2 J/g· ºC (rounded off) Specific heat capacity of Ice = CI= 2.1 J/g· ºC (rounded off) ∆T = change in temperature of water from initial to equilibrium ∆T1 = Change in temperature of ice from negative to 0 o. ∆T2 = Change in temperature of ice from 0o to the equilibrium temperature. Latent Heat of Table Fusion ofShowing Ice = Lf By wat er

the Calculations

Energy Lost – Formula

Mass of water x Cw x ∆T

Energy Lost – with substituted values

50 x 4.2 x 20.2

Energy Lost

4242 Joules

Heat Lost = Heat Gained By Ice

Energy Gained – Formula

(Mass of Ice x CI x ∆T1) +(Mass of Ice x Lf ) +(Mass of Ice x CI x ∆T2)

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Energy Gained – with substituted values

(13.2 x 2.1 x 5.4) + (13.2 x Lf) + (13.2 x 2.1 x 7.4) =149.668 + 205.128 + (13.2 x Lf)

Latent Heat of Fusion of Ice - with substituted values Latent Heat of Fusion of Ice

Lf = 4242 – (149.668 + 205.128) 13.2 294.5 Joules/gram

Conclusion:As seen in the calculations above, the latent heat of fusion was found to be 294.5 Joules/gram. The actual latent heat of ice, as mentioned in the introduction, is 333 Joules/gram. •

Error percentage 333 – 294.5 = 38.5 (38.5 / 333) x 100 = 11.6 Therefore, the error % was 11.6%. This means that the result obtained from this experiment was 11.6% inaccurate or (100 – 11.6 = 88.4) 88.4% accurate.

Evaluation:There could have been a number of error that might have occurred causing an inaccuracy in the experiment results that were obtained: The ice from when it was removed from the freezer & bought to the apparatus could have melted a little gaining some energy from the atmosphere causing an error while calculating the total heat gained by the ice.  There might have been some heat loss from the copper beaker in the calorimeter to the atmosphere causing an error while calculating the total heat lost by water.  The total heat loss might not have been equal to the total heat gained  The apparatus may have had some errors for example; the digital balance & the digital thermometer might have got affected by the minor surrounding changes. 4

 There may have been a parallax error while measuring the volume of water in the measuring cylinder.  All calculations were made using figures that were rounded off to make the calculations more simplified which may have added to the inaccuracy in the final figures obtained for the latent heat of fusion of ice.  The experiment could not be repeated due to time constraints so the average could not be taken which would have been more accurate.

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