Question

Heat, q, is energy transferred between a system and its surroundings. For a process that involves a temperature change

q=m⋅Cs⋅ΔT

where Cs is specific heat and m is mass.

Heat can also be transferred at a constant temperature when there is a change in state. For a process that involves a phase change

q=n⋅ΔH

where, n is the number of moles and ΔH is the enthalpy of fusion, vaporization, or sublimation.

The following table provides the specific heat and enthalpy changes for water and ice.

Substance	Specific heat [J/(g⋅∘C)]	ΔH (kJ/mol)
water	4.18	44.0
ice	2.01	6.01

Part A.) Calculate the enthalpy change, ΔH, for the process in which 33.6 g of water is converted from liquid at 8.6 ∘C to vapor at 25.0 ∘C . For water, ΔHvap = 44.0 kJ/mol at 25.0 ∘C and Cs = 4.18 J/(g⋅∘C) for H2O(l).

Express your answer to three significant figures and include the appropriate units.

Part B.) How many grams of ice at -18.7 ∘C can be completely converted to liquid at 12.1 ∘C if the available heat for this process is 4.18×10³ kJ ?For ice, use a specific heat of 2.01 J/(g⋅∘C) and ΔHfus=6.01kJ/mol.

Express your answer to three significant figures and include the appropriate units.

Answer 1