Question

Am I correct?
From data below, calculate the total heat (J) needed to convert 0.539 mol gaseous ethanol at 300°C and 1 atm to liquid ethanol at 25.0°C and 1 atm.

Boiling point at 1 atm 78.5°C
c ethanol gas 1.43 J/g·°C
c ethanol liquid 2.45 J/g·°C
ÄH°vap 40.5 kJ/mol


help please Answer in J

my work:
.539 x 46= 24.79
24.79 x 1.43 x -221.50= -7852 J
.539 x -40.5= -21,829 J
24.79 x 2.45 x -53.5 = 32930 J

then -7852 + -21, 829 + -3249= -32930 J

Answer 1

539 x 46= 24.79
24.79 x 1.43 x -221.50= -7852 J
.539 x -40.5= -21,829 J
24.79 x 2.45 x -53.5 = 32930 J

<b>I would have rounded step 2 and step 3 differently but other than that I don't have any problems with steps 1, 2, or 3.
For step 4 I think you made a typo here and put the answer of 32930 J for total instead of -3249 J for this tep. I think that answer should be -3249 J.

I'm a little confused about what the question actually wants. If the question want's total heat (liberated) when ethanol goes from 300 to 25 then your 32930 J is correct. If the question wants total heat from 300 to 25 then -32930 J is right but I notice the problem actually says "how much is NEEDED in ....". Actually there is no heat needed since each of these steps is exothermic each step gives off heat and none is needed. ;-)</b>