From data below, calculate the total heat (in J) associated with the conversion

Question

From data below, calculate the total heat (in J) associated with the conversion of 0.481 mol ethanol gas (C2H6O) at 401C and 1 atm to liquid ethanol at 25.0C and 1 atm. (Pay attention to the sign of the heat.)

Boiling point at 1 atm 78.5C cgas 1.43 J/gC cliquid 2.45 J/gC Hvap 40.5 kJ/mol From data below, calculate the total heat (in J) associated with the conversion of 0.481 mol ethanol gas (C2H6O) at 401½C and 1 atm to liquid ethanol at 25.0½C and 1 atm. (Pay attention to the sign of the heat.) Boiling point at 1 atm 78.5½C cgas 1.43 J/g H½vap 40.5 kJ/mol ½C ½C cliquid 2.45 J/g

Explanation / Answer

se molar mass to find grams of ethanol
0.505 moles ethanol @ 46.07 g/mol = 23.265 grams of ethanol

to cool the gas to 78.5C
dH = 23.265 g (1.43 J/g-C) (22.5C)
dH = 748.55 Joules must be released

to condense the gas@ 78.5C
dH = nC
dH = 0.505 moles (40,500 Joules/mol)
dH = 20452.5 JOules

to cool the liquid to 25.0C
dH = m C dT
dH = 23.265 g ( 2.45 J/g-C) (53.5C)
dH = 3049.46 Joules released

that's a total of 24,250.5 Joules

at 3 sig figs
it rounds off to
dH total = - 24.3 kJ

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