# Heat: Change in phase and latent heat capacity

1) 1 kg of ice is taken from a temperature of -34 o C into steam at 161 o C. To the nearest kJ what is the energy used?

2) 2 kg of ice at 0 oC is dropped into 3.99 kg of water at 13 oC. To two decimal places what fraction of the ice melts?

3) 1 kg of ice at -30 oC is dropped into 25 kg of water at 56 oC. To the nearest tenth of a degree Celsius, what is the final temperature of the mixture?

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1 kg of ice is taken from a temperature of -34 oC into steam at 161 oC. To the nearest kJ what is the energy used?

The energy supplied is changing the thermal state of ice in the following steps.

1. To increase temperature of ice from -340C to 00C.

The amount of energy required Q1 to increase temperature of the substance is given by the formula

Q1 = mass*specific heat*increase in temperature

= 1kg*(2.06*103J/kg/0C)*[0 - (-34)] = 70040 J

2. To the change the phase at 00C from solid to liquid i.e. from ice to water

The amount of energy required Q2 is given by

Q2 = mass*latent heat of melting of ice

= 1Kg*(3.33*105 J/kg) = 333000 J

3. To increase the temperature of water from 00C to 1000C,

Q3 = mass*specific heat*increase in temperature

= 1kg*(4.18*103J/kg/0C)*(100 - 0) = 418000 J.

4. To change the phase at ...

#### Solution Summary

Three problems related to change in temperature, mixing, change in phase and latent heat are solved.