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Heat of combustion help

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mylinh-nguyen:
The heat of combustion of 1-propanol is reported to be 33.63kJg^-1
The equivalent molar heat of combustion of 1-propanol is closest to:
a)1549 kJmol
b)1987 kJmol
c)2021 kJmol
d)2525 kJmol
how do you do this question?????

kiwiberry:

--- Quote from: mylinh-nguyen on July 16, 2017, 03:04:17 pm ---The heat of combustion of 1-propanol is reported to be 33.63kJg^-1
The equivalent molar heat of combustion of 1-propanol is closest to:
a)1549 kJmol
b)1987 kJmol
c)2021 kJmol
d)2525 kJmol
how do you do this question?????

--- End quote ---

Hey! Here we have to convert kJ/g into kJ/mol. To do this, we can multiply 33.63 kJ/g by the molar mass of propanol, since the molar mass has units g/mol - see how the units cancel out? :)

MisterNeo:

--- Quote from: mylinh-nguyen on July 16, 2017, 03:04:17 pm ---The heat of combustion of 1-propanol is reported to be 33.63kJg^-1
The equivalent molar heat of combustion of 1-propanol is closest to:
a)1549 kJmol
b)1987 kJmol
c)2021 kJmol
d)2525 kJmol
how do you do this question?????

--- End quote ---

Hi! :)
For this question, they give you the heat of combustion in kJ per gram but you need it in kJ per mole.
You would multiply the kJ by the molar mass of propanol.
So the answer would be...

So the answer is C. ;)

Edit: kiwiberry beat me to it ._.

mylinh-nguyen:

--- Quote from: kiwiberry on July 16, 2017, 03:13:56 pm ---Hey! Here we have to convert kJ/g into kJ/mol. To do this, we can multiply 33.63 kJ/g by the molar mass of propanol, since the molar mass has units g/mol - see how the units cancel out? :)


--- End quote ---

oh I get it thank you!!!

mylinh-nguyen:

--- Quote from: MisterNeo on July 16, 2017, 03:15:37 pm ---Hi! :)
For this question, they give you the heat of combustion in kJ per gram but you need it in kJ per mole.
You would multiply the kJ by the molar mass of propanol.
So the answer would be...

So the answer is C. ;)

Edit: kiwiberry beat me to it ._.

--- End quote ---
thanks for your help too!

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