What amount of energy is required to melt a 24.9 g piece of ice at 0 o C? The he

Question

What amount of energy is required to melt a 24.9 g piece of ice at 0oC?
The heat of fusion of ice = 333 Jg-1

Heat required to melt the ice = J

What amount of energy must be removed from 111 g of water to cool it from 76.6oC to 8.18oC?
Specific heat of water = 4.184 JK-1g-1

Enter the heat as a negative amount (heat removed from a system is by convention always negative).
Heat removed to cool the water = J

What is the final temperature after a 24.9 g piece of ice is placed into a styrofoam cup containing 111 g of hot water at 76.6oC. The mass of the ice, and the mass and initial temperature of the hot water are the same as in the two previous parts of this question.

Final temperature = oC

Explanation / Answer

a) Heat required to melt the ice = 24.9 *333 = 8291.7 J = 8.2917 kJ

b)Q = m*c*(delta T)

Q = heat energy
m = mass
c = specific heat
delta t = change in temperature (= final - initial temp)

Remember, in a closed system, heat gained by one thing equals the heat lost by another.

Heat removed to cool the water = - m *s * delta T = -111*4.184* (76.6-8.18) = 317775 . 89 J

c)In a closed system no heat is lost to outside

Heat lost by hot body = heat gaine by cold body

Heat lost by hot water = heat gained by ice

Let the final temperature be T

The ice has to first convert into water and then to change its to temperature to T ..... So there is heat required for conversion of ice to water too ...

Then ,

24.9*(333) + 24.9*4.184* T = 111*(76.6-T)

T(215.18) = 111*76.6-24.9*333 = 144.3

T = 0.67 oC

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