%3Cp%3E%3Cspan%20class%3D%22c1%22%3EHow%20much%20heat%20energy%20is%20required%2

Question

%3Cp%3E%3Cspan%20class%3D%22c1%22%3EHow%20much%20heat%20energy%20is%20required%20to%20convert%0A33.5%20g%20of%20solid%20ethanol%20at%20-114.5%20%C2%B0C%20to%20gasesous%20ethanol%20at%20165.7%0A%C2%B0C%3F%20The%20molar%20heat%20of%20fusion%20of%20ethanol%20is%204.60%20kJ%2Fmol%20and%20its%0Amolar%20heat%20of%20vaporization%20is%2038.56%20kJ%2Fmol.%20Ethanol%20has%20a%20normal%0Amelting%20point%20of%20-114.5%20%C2%B0C%20and%20a%20normal%20boiling%20point%20of%2078.4%20%C2%B0C.%0AThe%20specific%20heat%20capacity%20of%20liquid%20ethanol%20is%202.45%20J%2Fg%C2%B7%C2%B0C%20and%0Athat%20of%20gaseous%20ethanol%20is%201.43%20J%2Fg%C2%B7%C2%B0C.%3C%2Fspan%3E%3C%2Fp%3E%0A

Explanation / Answer

Think about the process in stages.

First, you have to warm the solid ethanol to its melting point:

q = mcDT = 78.0g(0.97j/gK)(13K)= ___ J

Then, you have to melt the solid at -114 C:

q = 5.02 kJ/mol (78g/46 g/mol)= ___ kJ

THen, you have to warm the liquid to its boiling point:

q = 78 X 2.3 X 182 = ____ J

Then you have to vaporize the liquid

q = 33.5 X 78/46 = ____ kJ.

Finally, convert all the answers to kJ and add them up.

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