Calculate the amount of heat required to convert 10.0 grams of ice at –20.°C to steam at 120.°C. (Sp. heat of H2O(s) = 2.09 J/g•°C, Sp. heat of H2O(l) = 4.18 J/g•°C, Sp heat of H2O(g) = 2.03 J/g•°C; heat of fus. of H2O(s) = 333 J/g, heat of vap. of H2O(l) = 2260 J/g).

Answer : The amount of heat required is,

Solution :

The process involved in this problem are :

The expression used will be:

where,

= heat required for the reaction

m = mass of ice = 10.0 g

= specific heat of solid water or ice =

= specific heat of liquid water =

= specific heat of gaseous water =

= enthalpy change for fusion =

= enthalpy change for vaporization =

Now put all the given values in the above expression, we get:

Therefore, the amount of heat required is,