This question is in two parts. Ice of mass 22g at temperature -12Degrees C is taken from a freezer and placed in a polystyrene cup containing water at a temperature 22 degrees C. (a) Calculate the quantity of heat needed (i) to raise the temperature of the ice from -12 degrees C to 0 degrees C (ii) to change the ice to water without an increase in temperature.

Following on: The temperature of the water in the cup falls after the ice as been added. Specific heat capacity of water = 4200 J kg-1 K-1. (i) Calculate the mass of the water in the cup if the lowest temperature reached by the water is 8 degrees C.

Question

This question is in two parts. Ice of mass 22g at temperature -12Degrees C is taken from a freezer and placed in a polystyrene cup containing water at a temperature 22 degrees C. (a) Calculate the quantity  of heat needed (i) to raise the temperature of the ice from -12 degrees C to 0 degrees C (ii) to change the ice to water without an increase in temperature.

Following on: The temperature of the water in the cup falls after the ice as been added. Specific heat capacity of water = 4200 J kg-1 K-1. (i) Calculate the mass of the water in the cup if the lowest temperature reached by the water is 8 degrees C.

anonymous · Answer

The first one is solved using$$Q = mc \Delta T$$where m is the mass of the ice, c is the specific heat of ICE, and $\Delta T$ is the change in temperature. Temperature does not need to be in an absolute scale (Kelvin or Rankine). Make sure the units of mass and temperature align with those on specific heat. 

The second one is solved using$$Q = m h_f$$where m is the mass of the ice and $h_f$ is the heat of fusion of ice.

anonymous · Answer

Can we assume the polystyrene cup is well-insulated and closed to its surroundings?

anonymous · Answer

Why not. The problem would be unsolvable without those assumptions.