A piece of ice of mass `50 g` exists at a temperature of `-20^(@)C`. Determine the total heart required to covert it completely to steam at `100^(@)C`. (Specific heat capacity of ice `= 0.5 cal//g-^(@)C`, specific latent heat of fusion for ice `= 80 cal//g` and specific latent heat of vaporization for water `= 540 cal//g`).

Options

A. 425g
B. 525g
C. 625g
D. 725g

Answer

A

Explanation

Let m grams be the mass of the steam.
Heat lost by the steam `= m xx L + m xx 1 xx (100-0)`
`=m xx 540 + 100m = 640m`
Heat gained by ice `=m_(i) xx s xx Delta T + m_(i)L`
`=3200 xx 0.5 xx [0-(-10)] + 3200 xx 80`
=272000 cal
According to the principle of calorimetry.
640m = 272000 or m= 425g