Enthalpy
I'm given that the heat of reaction for the combustion of ethane is -1560kJ/mol. I need to figure out how much heat is produced from 18g of ethane.
2 C2H6 + 7 O2 --> 4 CO2 + 6 H2O
Okay so I'm rough on Thermo right now, so I gave it my best shot. Could we write each molar amount from the equation as equal to the heat of reaction:
2mol ethane = -1560kJ/mol
7mol oxygen gas = -1560kJ/mol
4mol carbon dioxide = -1560kJ/mol
6mol water = -1560kJ/mol
Then could I convert the given 18g of ethane into moles and convert to the heat produced, using -1560kJ/mol as the heat converting value:
(18g ethane)/(30.07g/mol ethane) = .599mol ethane
(.599mol ethane)/(2mol ethane)*(-1560kJ/mol ethane) = -467.22kJ
Okay so my previous problem was going to be the fact that my final answer was -279.7kJ instead of -467.22kJ (my computer calculator doesn't show history so I don't know what dumb thing I did!)
However, here are the answers available:
A) -220.5kJ
B) -466.75kJ
C) 300.21kJ
D) 424.67kJ
So the right answer is B? Ethane, or 18g of ethane, releases about 467.22kJ or 466.75kJ? Or do these two values vary too much as to refute my calculations?
To calculate the amount of heat produced from 18g of ethane, you need to follow these steps:
Step 1: Calculate the number of moles of ethane
To convert mass to moles, you can use the formula:
moles = mass / molar mass
In this case, the molar mass of ethane (C2H6) is 30.07 g/mol.
moles of ethane = 18g / 30.07 g/mol
= 0.599 mol
Step 2: Use the heat of reaction to calculate the heat produced
Now that you know the number of moles of ethane, you can use the heat of reaction (-1560 kJ/mol) to calculate the heat produced.
heat produced = moles of ethane x heat of reaction
= 0.599 mol x (-1560 kJ/mol)
= -935.64 kJ
So the correct answer should be -935.64 kJ.
However, let's compare this value with the given answer choices:
A) -220.5 kJ
B) -466.75 kJ
C) 300.21 kJ
D) 424.67 kJ
None of the given answer choices match our calculation (-935.64 kJ). It appears there might be an error in the given answer options or the heat of reaction value. I recommend rechecking the problem or confirming the correct answer with your instructor or textbook.