Question

the amount of heat required to convert 1 gram of water at 30 degree centigrade into steam at 100 degree centigrade

Answer 1

The amount of required to raise the temperature of a unit mass of substance through a unit rise in temperature, without the phase-change, is called the "Specific-Heat" of the substance..Whereas "Latent-Heat" is the amount of heat required to change the phase of a unit mass of substance..Now for the phase change from solid-ice to liquid-water, heat required is (1 gm)(80 cal/gm) = 80 cal.To raise the temperature of water from 0 to 100 (celsius), heat required is(1 gm)(1 cal/gm/K)(100 K) = 100 cal.Again for the phase change from liquid-water to gaseous-steam, heat required is (1 gm)(540 cal/gm) = 540 cal.Summing up the entire thing you get, total heat required = 720 cal = 0.72 kcal.