# Some very hot rocks have a temperature of #420 ^o C# and a specific heat of #210 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

You will need lots of rocks or one big boulder...roughly with dimensions of

#### Explanation:

Given or Known:

Unknown: Heat required vaporize ice and

Required:

**Calculate: Heat Required to vaporized the water**

**Calculate: the heat gained by liquid water**

At boiling point all the, further addition of energy causes the substance to undergo vaporization. All the added thermal energy converts the substance from the liquid state to the gaseous state. The temperature does not rise while a liquid boils.

So

**Calculate: the heat loss by the rock as it cools down to #100^oC#**

Now the heat loss by rock above is used up to vaporize the 45 kg of water. At thermal equilibrium

You will need lots of rocks or one big one...roughly with dimensions of