Thermoohemistry Problems Total: 27 Points Possible 1. How much heat is produced
ID: 546336 • Letter: T
Question
Thermoohemistry Problems Total: 27 Points Possible 1. How much heat is produced by burning 2.50 moles of acetylene under standard state conditions? Heat of combustion of acetylene is 301.1 kJ/mol. (3 pts) 2. How much heat is produced by combustion of 225 g of methanol under standard state conditions? Heat of combustion of methanol is 726.1 k.Wmol. (3 pts) 3. How many moles of isooctane must be burned to produce 200 kJ of heat under standard state conditions? Heat of combustion of isooctane is 5461 kJlmol. (3 pts) 4. A 0.500-g sample of KCI is added to 50.0 g of water in a calorimeter. If the temperature decreases by 1.05 "C, what is the approximate amount of heat involved in the dissolution of the KCI, assuming the heat capacity of the resulting solution is 4.18 Jig "C? Is the reaction exothermic or endothermic? (3 pts) 5. Dissolving 5.0 g of CaC12(s) in 150.0 g of water in a calorimeter at 22.4'C causes the temperature to rise to 27.8 *C. What is the approximate amount of heat involved in the dissolution, assuming the heat capacity of the resulting solution is 4.18 g "C? Is the reaction exothermic or endothermic? (3 pts tors4/T7, 12 00 AM Page 1 of 2 794724 try%20eroblems.docaExplanation / Answer
1)
Given
No. of moles of Acetylene = 2.5 moles
Heat of combustion of acetylene = 301.5 kJ/mol
Heat produced = No. of moles * Heat of combustion = 2.5 moles * 301.5 kJ/mol = 753.75 kJ Answer
2)
Given
Mass of methanol = 225 g
Molar mass of methanol = 32 g/mol
No. of moles of methanol = 225 g / 32 g/mol = 7.03 moles
Heat of combustion of methanol = 726.1 kJ/mol
heat produced = No. of moles * heat of combustion = 7.03 moles * 726.1 kJ/mol = 5105.4 kJ Answer
3)
Given
Heat released = 200 kJ
Heat of combustion of isooctane = 5461kJ/mol
No. of moles of isooctane required = Heat released / Heat of combustion of isooctane = 200 kJ / 5461 kJ/mol
No. of moles of isooctane required = 0.037 moles Answer
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