Question

How many kilograms of water can be heated from 50°C to 75°C by co steam at 100°C? an be heated from 50°C to 75°C by condensing 1 kg of A. 10.2 kg B. 15 kg C. 21.5 kg D. 25.6 kg

Answer 1

Answer : The mass of water heated will be, (C) 21.5 kg

Explanation : Given,

Initial temperature =
`50^oC`

Final temperature =
`75^oC`

The value of latent heat of vaporization of steam at
`100^oC` = 2260 kJ/kg

Specific heat of water =
`4.184kJ/kg^oC`

Formula used :

`Q=m* C_w* \Delta T`

or,

`Q=m* C_w* (T_2-T_1)`

where,

Q = latent heat of vaporization of steam

m = mass of water

`C_w` = specific heat of water

`T_1` = initial temperature

`T_2` = final temperature

Now put all the given value in the above formula, we get:

`2260kJ/kg=m* 4.184kJ/kg^oC* (75-50)^oC`

`m=21.5kg`

Therefore, the mass of water heated will be, 21.5 kg