Enthalpy Worksheet With Answers Page 3
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62. A burner on an electric range has a heat capacity of 345J/K. What is the value of q, in
o
kilojoules, as the burner cools from a temperature of 467
C to a room temperature of
o
23
C?
Answer
5
q = C∆T = (345J/K)(23-467) = -1.53x10
J = -153kJ
Molar Heat Capacity/Specific Heat
1. How much heat, in calories and kilocalories, does it take to raise the temperature of
o
o
814g of water from 18.0
C to 100
C?
Answer
o
o
o
4
q = mc∆T = (814g)(1cal/g
C)(100
C – 18
C) = 6.67x10
cal = 66.7Cal (kcal)
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o
10
2. What mass of water, in kilograms, can be heated from 5.5
C to 55.0
C by 9.09x10
J
of heat?
Answer
10
o
o
o
8
5
m = q/c∆T = 9.09x10
J / (4.180J/g
C)(55.0
C – 5.5
C) = 4.39x10
g = 4.39x10
kg
o
3. A 454g block of lead is at an initial temperature of 22.5
C. What will be the
temperature of the lead after it absorbs 4.22kJ of heat from its surroundings?
Answer
3
o
o
∆T = q / mc
= 4.22x10
J / (454g)(0.128J/g
C) = 72.6
C
Since heat is absorbed the temperature will go up
o
o
o
The final temperature is 22.5
C + 72.6
C = 95.1
C
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