Question

2 gm of steam condenses when passed through 40 gm of water initially at 25 C the condensation of steam raises the temperature of water to 54.3 C what is the latent heat of steam ? plz help me with this question
the ans will be 540 cal/g

Answer 1

Let L be the latent heat and using principle of calorimetry. 2L + 2 (100 ? 54.3) = 40 ´ (54.3 ? 25.3) Þ L = 540.3 cal/gm.

Answer 2

We have to use calorimetry principle to solve this problem. That means,

heat lost by hot object = heat gained by cold object ------- (1)

heat lost by steam = heat gained by water (see attached document )

             mL + mSΘ = MSΘ

Where, m = mass of steam =2g

            L = latent heat of steam

            S = specific heat capacity of water in cal = 1cal/g°c

            M = mass of water = 40g

            Θ = temperature differences in Celsius

$2L + 2*1*(100-54.3) = 40(54.3-25)$

          $2L + 2(45.7) = 40(29.3)$

               $2L + 91.4 = 1172$

                           $2L = 1080.6$

                             $L = 540.3$

Answer : latent heat of steam = 540.3 cal/g