Question

A container has `12 L` of water in it at `90 ^o C`. An object with a specific heat of `750 (KJ)/(Kg*K)` and a temperature of `210 ^oC` is placed into the container. If the water is completely vaporized, what is the object's mass?

Answer 1

The mass of the object is `=334.4kg`

Explanation:

The heat transferred from the object to the water, is equal to the heat used to raise the temperature of the water to `100ºC` and to evaporate the water.

For the object `DeltaT_o=210-100=110º`

For the water `DeltaT_w=100-90=10º`

Heat of vaporisation of water

`H_w=2257kJkg^-1`

Specific heat of water is `C_w=4.186kJkg^-1K^-1`

The specific heat of the object is

`C_o=0,75kJkg^-1K^-1`

The mass of water is `m_w=12kg`

`m_o C_o (DeltaT_o) = m_w*C_w*10+m_w H_w`

`m_o*0.75*110=12*4.186*10+12*2257`

The mass of the object is

`m_o=(12*4.186*10+12*2257)/(0,75*110)`

`=334.4kg`