Question

How much steam at 100° C is to be passed into water of mass 100 g at 20° C to raise its temperature 5° C? (Latent heat of steam is 540 cal/g and specific heat of water is 1 cal/g° C)

Answer 1

heat lost by steam = mLv
where Lv is latent heat of vaporisation.
so, heat lost by stream = m × 540

heat gained by water = ms∆T = 100 × 1 × 5
= 500cal

here, heat lost by steam = heat gained by water

or, m × 540 = 500

or, m = 50/54 = 25/27 g =0.9259g

hence, mass of steam = 0.9259g

Answer 2

Answer:

0.813 grams of steam is required to change its temperature by 5 degrees celcius.