Q2 of 11 Page 89

A solid of initial temperature 0°C is heated. A graph showing changes in the temperature according to the heat supplied is given below.


Based on the graph calculate the following. (Specific heat capacity of the substance: 500J kg–1 K–1)


(a) the mass of solid substance


(b) the latent heat of fusion of the substance

(a) The mass of the solid substance

Given


Specific heat capacity of the substance = 500J kg–1 K–1


Energy to change temperature from 0C to 80C = 1000J


(from Graph)


Mass = ?


Formula used


Q = mc(ΔT)


m is the mass (Kg)


c is the specific heat of ice (J/kg-K)


ΔT is the temperature difference(K)


ΔT = 80


C = 500


Q = 1000


M = ?


500 J/kg-K × 80K × m(kg) = 1000J


M = 25gm


(b) the latent heat of fusion of the substance


Given


Mass of ice = 25gm


Energy from B to C = 1000J (to convert ice to water)


Latent heat of fusion = ?


Formula Used


Q = mF


where m is the mass (Kg)


F is the latent heat of fusion of ice (J/kg)


Q = 1000J


M = 25gm = 0.025 kg


F = ?


F J/Kg × 25/1000Kg = 1000J;


latent heat of fusion is 40000J/Kg.


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7

2 kg of water at 293 K is converted completely into ice at 273 K. Calculate the heat liberated.

 1

2 kg of ice at –10°C is continuously heated to melt it completely. Calculate the quantity of heat required. (The latent heat of fusion of ice: 336 × 103 J/kg. The latent heat of vaporization of water: 226 × 104 J/kg. Specific heat capacity if ice: 2.1 × 103 J/kg K. Specific heat capacity of water: 4.2 × 103 J/kg K.)

 3

A hole was drilled in an ice block at 273 K. When the hole was filled with water at 373 K, 2 kg of ice melted and changed into water at 273 K. If so, what is the mass of water at 373 K that was used? (Specific heat capacity of water 4200 J kg–1 K–1, latent heat of fusion of ice: 336 × 103 J/kg)

 4

Collect information regarding different kinds of thermometers and record the situations in which they are used. (hint: ma× imum – minimum thermometer).