Question

A container has `8 L` of water in it at `20 ^o C`. An object with a specific heat of `360 (KJ)/(Kg*K)` and a temperature of `540 ^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 `=0.131kg`

Explanation:

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

For the object `DeltaT_o=540-100=440º`

Heat of vaporisation of water

`H_w=2257kJkg^-1`

The specific heat of the object is

`C_o=360kJkg^-1K^-1`

The mass of water is `m_w=8kg`

`m_o C_o (DeltaT_o) = m_w H_w`

`m_o*360*440=8*2257+8*80*4.186`

The mass of the object is

`m_o=(8*2257+8*80*4.186)/(360*440)`

`=0.131kg`