ICSE Class 10 Physics 2017 Solved Paper

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Question : 34
Total: 65
Calculate the mass of ice needed to cool 150g of water contained in a calorimeter of mass 50g at 32C such that the final temperature is 5C.
Specific heat capacity of calorimeter =0.4J gCC
Specific heat capacity of water =4.2JgC
Latent heat capacity of ice =330Jg
Solution:  
Let the mass of ice be =mg .
As ice will gain heat from calorimeter and water, it will undergo conversion as :
Ice Water Water
(at 0C ) (at 0C ) (at 5C )
So, heat gained =mL+mcT
=m×330+m×4.2×(50)
=330m+21m
=(351m)J.
Heat is lost by calorimeter and water both,
Heat lost by calorimeter
=m1c1T1
=50×0.4×(325)
=540J
Heat lost by hot water
=m2CWT2
=150×4.2×(325)
=150×4.2×27
=17010J
Total heat lost =540+17010=17550J
By the principle of calorimetry
Heat gained = Heat lost
351m=17550
or m=
17550
351
=50g

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