Some very hot rocks have a temperature of #630 ^o C# and a specific heat of #270 J/(Kg*K)#. The rocks are bathed in #45 L# of boiling water. If the heat of the rocks completely vaporizes the water, what is the minimum combined mass of the rocks?
1 Answer
Explanation:
When the rock is dropped in water, its temperature reduces. The water is already at boiling temperature. This means two things -
- The minimum temperature that the rock can reach is the boiling temperature of water (
#100 ^ o C# ), - All the heat gained by the water is used for phase change from the liquid phase to the vapour phase.
To find the minimum mass of the rock that completely vaporises the water, we have to equate the heat lost by the rock of unknown mass
Heat Lost by Rock:
Heat gained by water: