Question

liquid ammonia is used in ice factory for making Ice from water water at 20 degree celsius is to be converted into 2 kg ice at 0 degree Celsius how many grams of ammonia are to be evaporated

Answer 1

Here the heat taker is ammonia (NH3)
Heat giver is the water (20°-0°) and from 0° liquid to solid 0° i.e. (0°-0°)

Solution:-
Q1 =Q2 + Q3
mL = mc t + mcL
where L= latent heat of ammonia i.e. 341(L.H.S)
L = latent heat of water i.e. 80
m= mass of water i.e. 2000gm (R.H.S)
t = change in temperature (20°- 0°)

Substituting the values we get,

m×341 =2000 ×1 × (20 - 0) + 2000 × 80
341m = 2000 × 20 + 160000
341m = 40000 + 160000
341m = 200000
m = 200000÷341
m = 586.51 gm


Therefore, the ammonia used in the factory is 586.51 gram