Heat, q , is energy transferred between a system and its surroundings. For a pro

Question

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

q=m?Cs??T

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??H

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

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

6.01

Part A

Calculate the enthalpy change, ?H, for the process in which 31.3 g of water is converted from liquid at 9.1 ?C to vapor at 25.0 ?C .

For water, ?Hvap = 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 -25.5 ?C can be completely converted to liquid at 14.7 ?C if the available heat for this process is 5.09×103 kJ ?

For ice, use a specific heat of 2.01 J/(g??C) and ?Hfus=6.01kJ/mol.

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

6.01

Explanation / Answer

44*25=1100

1100/2.01=547.26

44*25=1100

1100/2.01=547.26

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