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 :

$Q=m\times C_w\times \Delta T$

or,

$Q=m\times C_w\times (T_2-T_1)$

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:

$2260kJ/kg=m\times 4.184kJ/kg^oC\times (75-50)^oC$

$m=21.5kg$

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