Chemistry

Name: ___________________________

Thermochemistry Worksheet #5: Total Energy Calculations o

1. Calculate the total energy change that occurs when 100.0 kg of steam at 150.0 C changes to water o o o with a final temperature of 60.0 C. (c H2O(g) = 2.01 J/g C; c H2O(l) = 4.184 J/g C; ΔHvap = 40.7 kJ/mol) 5 (Ans: -2.53  10 kJ)

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2. Find the total energy required to change 75.0 g of lead at 25.0 C from a solid to a liquid at its melting o point of 328 C. The molar heat of fusion for lead is 5.0 kJ/mol and its specific heat capacity is 0.159 o J/g C. (Ans: 5.4 kJ)

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Chemistry

Name: ___________________________ o

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3. Find the total energy absorbed as 10.0g of methanol at 50.0 C is heated to 110.0 C. The boiling point o o o of methanol is 65.0 C. (cCH3OH (l) = 4.66 J/g C; c CH3OH (g) = 2.51 J/g C; ΔHvap = 39.23 kJ/mol). (Ans: 14.0 kJ)

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4. How much heat would be required to change 3.60 kg of ice at –10.0 C to steam at 100 C? o o (cH2O (s) and (g) = 2.01 J/g C; cH2O (l) = 4.184 J/g C; ΔHfus = 6.02 kJ/mol; ΔHvap = 40.7 kJ/mol) 4 (Ans: 1.09  10 kJ)

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