Question

22.) The molar heats of fusion and vaporization for water are 6.02 kJ/mol and 40.6 kJ/mol, respectively, and the specific heat capacity of liquid water is 4.18 J/gC. (1) What quantity of heat is required to melt 25.0 g of ice at 0C? (2) What quantity of heat is required to vaporoze 3.75 g of liquid water at 100C? (3) What quantity of heat is required to heat to warm 55.2 g of liquid water from 0C to 100C
(1) 8350 J
(2) 84.6 J
(3) 23.1 J
23.) Given that the specific heat capacities of ice and steam are 2.06 J/gC and 2.03 J/gC, respectively, and considering the information about water given in Problem 22, calculate the total quantity of heat evolved when 10.0 g of steam at 200C is condensed, cooled, and frozen to ice at -50C.

Answer 1

1. q = mass ice x heat fusion
2. q = mass H2O x heat vaporization
3. q = mass H2O x specific heat H2O x (Tfinal-Tinitial)

23. A Loooong problem. Here is the way you do it.
Formula for q WITHIN a phase.
mass x specific heat x (Tfinal-Tinitial).

Formula for q at a phase change.'
freezing: mass x heat fusion
boiling: mass x hat fusion.

Then add the segments for total q.