# Complete Combustion of Butanol

## Recommended Posts

i have got these bond energies:

Butanol 5580 (total)

Water 928

Carbon Dioxide 1210

oxygen 498.3

When i work out the total bond energies on both sides, it shows me that the complete combustion of Butanol is ENDOTHERMIC!!!! Whats wrong with my calculation

C4H9OH + 6O2 ----------> 4CO2 + 5H2O

14149.8 11080

See?

##### Share on other sites

butanol as in Butan-1-ol CH3(CH2)2CH2OH ?

##### Share on other sites

well, honestly to tell you, i havent a clue what you are talking about!!! But all i know, is that the butanol we are using has a formula of C4H9OH

P.S i read ur question on the smallest movement that is detected and i have a question, Why do u ask impossible-to-answer questions lol

##### Share on other sites

LOL, well in reverse order, its not an impossible question, there has to be some threshold for this movement idea.

Next, lets have a look at your formula....

C4 H9 OH well we can re-shuffle those a little as theres 2 piles with H in it

C4 H10 O1

and we have as many Oxygens as we can use in our air too

we can make 4 lots of CO2 using 8 O from the air

and 5 lots of H2O using 4 lots of O from the air and remaining Oxygen in our fuel.

total air usage to combust 1 molecule of butanol would be 8 oxygen from the Air.

leaving 4 parts CO2 and 5 parts water

and completely combusted... can you work from there?

##### Share on other sites

so is the balanced equation:

c4h9oh + 8o2 ------------> 4co2 + 5h20

?????

##### Share on other sites

4O2 MOLECULES or 8 individual Oxygen ATOMS

and thats it

##### Share on other sites

shouldnt it be 3 o2 as in ur equation there are 9 on the left and 7 on the right???

##### Share on other sites

well unless Ive made a grave mistake, yup, thats it

thats how I was taught anyway

post #4 should demonstrate it all (at least in principal).

##### Share on other sites

yeah, cause, looking at the equation:

c4h9oh + 4o2 ------------> 4co2 + 5h2o

|

3O2 is needed to correct it

##### Share on other sites

aommaster said in post #5 :

so is the balanced equation:

c4h9oh + 8o2 ------------> 4co2 + 5h20

?????

4x CO2 (thats 4xO2)

5x H2O (thats 5xO... or 2xO2 and just a single O)

dont forget the fuel contains ONE of the O atoms

I count 13 O ATOMS from the air, or 6 O2 molecules and 1 ATOM.

and one used from the fuel making it 7O2

##### Share on other sites

OH sorry

sorry

i didnt count the 4 in fornt of the carbon

ok

thanx

no worries

##### Share on other sites

umm...

i wroked it out, BUT I STILL GOT AN ENDOTHERMIC REACTION!!!!

but i now get

13153.2 -------------->11080

##### Share on other sites

PASS? youve really lost me there dude?

##### Share on other sites

well, ill write out the whole reaction so u can see

C4H9OH + 4O2 --------------->4CO2 + 5H2O

(2 x 5580) + (4 x 498.3) ----------> (4 x 1610) + (5 x 928)

13153.2-------------------> 11080

##### Share on other sites

well thats not right, coz 4O2 will just do the Carbon.

where did the Hydrogen get its 2 and half O2 molecules from?

##### Share on other sites

man, im more confused then u r!!!!

I confused myself!!!

ok, what do we have to do now to correct the equation above?

##### Share on other sites

add 5 more Oxygen ATOMS or 2.5 O2 molecules, dont forget, you have a single spare O atom in your fuel

##### Share on other sites

so... would this be correct and balanced?

2C4H9OH + 12O2 -----------------> 8CO2 + 10H2O

##### Share on other sites

use the method in post #4, re-shuffle into neat little piles of 3 Different elements and work from there

then youll be able to answer that

##### Share on other sites

yeah. I wroked it out, its correct. Now the numbers before the chemicals are 2, 12 8 and 10, can i divide them by 2?

##### Share on other sites

theres 2 schools of thought about that in all honesty. for instance Phosphourous Pentoxide is often writen as P2O5 when in fact the molecule is P4O10.

so thats entirely up to you, whichever works best and remains factual at the same time, is great

##### Share on other sites

ok, so then, i'll divide it by 2 since my chemistry teacher tells be to simplify it. Thanx, and in case u were wondering y i was a total idiot, it was because im only in year 11, and balancing formulas as complex as this, i have not practiced

lol

##### Share on other sites

I wondered no such thing dude, as I said thats what were here for, just hope some the methods discussed were of benefit for future projects also.

All the Best

## Create an account

Register a new account