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Volume of gas needed to heat air in room

How much methane gas ( ) is required heat of air by ?DN N $

Please help! I thought this wouldn't be too difficult but I've been stuck for at least an hour now- so frustrating! Thank you so much in advance!

Edit: Thank you for the comment, here's what I did:

Let the specific heat capacity of air be (this is apparently the heat capacity for some average temperature and pressure- not sure ifit's reliable or not)

+

H,

)

DN

+ L+

Any help as to where I go from here? It appears that I should find out how many of is needed to produce (which isthe enthalpy change or ) and then find the volume of but I have no idea how to do that- either because I am not using the rightinformation or I'm just not very good with calculations (probably a mixture of both). Do I find the moles of in the room first?

NPM $)

L+

$)

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Second edit: Sorry! It's because half of them are just invalid as I got confused over which numbers to use and where. I tried using Charles'Law but that didn't work, then I thought I would find the enthalpy change but my units got messed up and there were allsorts of odd numbers coming up. Plus I spent quite a bit of time finding the heat capacities and densities etc.

Third edit: I solved it! First found out the from of room, then mol of needed to fill room (using knowledge that enthalpychange of is . Lastly found out volume by . ) $)

$)

L+ NPM

* 2

homework thermodynamics energy gas-laws

edited May 12 at 6:10Martin5,514 3 11 44

asked Dec 1 '13 at 11:52sonder31 4

The only values you need to look up to do the calculation are the molar combustion enthalpy of methane and thevolumetric heat capacity of air (actually you could even approximate the heat capacity to that of an ideal diatomicgas). Does that help? Nicolau Saker Neto Dec 1 '13 at 12:31

1

If you've been working on it for 'at least an hour' then can you show us what you have done, equations you haveused, and why you disregarded those approaches? bobthechemist Dec 1 '13 at 13:17

New edits. Thank you very much sonder Dec 1 '13 at 13:38

You've solved half of the problem; you know how much heat it takes to produce the required warming. Now, all youneed to know is how much methane produces that heat. Using the molar combustion enthalpy of methane, you canfind out how many moles it takes. With the number of moles, I imagine all you need to do is apply insome reasonable conditions, such as *

and . . Got it? Nicolau Saker Neto Dec 1 '13 at20:19

1

Wait, now I see you have a problem with units. If the specific heat of air you found is given in units of ,then you need to find the mass of air in #

. You need to know the initial temperature of the room to calculateit, though.)

Nicolau Saker Neto Dec 1 '13 at 20:31

1 Answer

1)

)

H- $

+

H $

N

L+

2) Find Mol required to fill room$)

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SFMFBTFT L+QFS NPM

L+

L+

NPM

NPM

3)

(coloured items are added by Martin upon Nicolau's comment.)

*

2

2 DN

* DN

NPM D

N

D

N

edited Jun 11 at 6:49Martin5,514 3 11 44

answered Dec 2 '13 at 8:10sonder31 4

Note that , so your answer is off by a factor of a thousand. ) Nicolau Saker Neto Dec 3 '13at 0:24

1 due to colors answer does not look boring :) Freddy Jun 11 at 10:19