I Keep getting the wrong answer..?

Question

Calculate the heat required to convert 27.9 g of propyl alcohol, C3H8O, from a solid at -147°C into the gaseous state at 111°C. The normal melting and boiling points of this substance are -127°C and 97°C, respectively. The heat of fusion is 86.2 J/g, and the heat of vaporization is 694 J/g. The specific heats of the solid, liquid and gaseous states are, respectively, 2.36, 2.83 and 1.76 J/g/K.

Answer 1

Here's what I did. Let propyl alcohol be called P

27.9gP x 20deg x 2.36J/deg-g = 1317J (P increased to its m.p.)

27.9gP x 86.2J/g = 2405J (P melts)

27.9gP x 224deg x 2.83J/deg-g = 17686J (P increased to its b.p.)

27.9gP x 694J/g = 19362J (P boils)

27.9gP x 14deg x 1.76J/deg-g = 687 (P vapor heated to 111C)

1317 + 2405 + 17686 + 19362 + 687 = 41,457J, which would be 41,500J to three significant figures.

Answer 2

Assuming constant specific heats (c) you can calculate the heat for changing the temperature from T1 to T2 by:
h= c*(T2-T1)
If there is change of state in the temperaturintervall, you have to calculate the change in each state up to the transition temperatur and add the heat of transition. For this problem this gives:

h= cs*(Tm-T1)+hm+cl*(Tv-Tm)
+hv+cv(T2-Tv)

cs - specific heat of solid
cl - specific heat of liquid
cv - specific heat of vapor
Tm - melting temperature
Tv - boiling temperature
hm - heat of fusion
hv - heat of vaporization


I get the following result
heating up solid 2.36*(-127- (-147))= 47.2 J/g
melting = 86.2 J/g
heating up liquid 2.83*(97-(-127)= 633.92 J/g
vaporization = 694 J/g
heating up vapor 1.76(111-97)= 24.64J/g

The sum is h=1485.96 J/g
The required heat is
H=m*h=27.9g * 1485.96J/g=41458.284J ~41.46kJ

Answer 3

H = 27.9 * (2.36 * (147 - 127) + 86.2 + 2.83 * (97 + 127) + 694 + 1.76 * (111 - 97)

H = 41458 joules = ~41500 J

Answer 4

What are the questions? I don't know what you're trying to figure out. 7 choose 0? 6 choose 6? 4 choose 3? What does that mean?