Register to reply

Co2 and Octane problem

by JABEMT
Tags: octane
Share this thread:
JABEMT
#1
Mar2-07, 02:16 PM
P: 1
I have the answer to the problem... only my problem is I can figure out how in the world world they came up with it. Here it is... I am sure it a pretty easy equation... only I don't get it!


Calculate the mass of CO2 produced by the combustion of a tank of gasoline. Assume the mass of gasoline is 41.0 kg and that gasoline is pure octane (C8H18); 1 lb =454 g. Express your answer rounded to the nearest whole number. Do not include units with your answer.

Correct answer: 278

I have tried converting the 41.0kg in to grams and got .041g.
I found the atomic mass of CO2 as 44 and X by 8 (research found Every molecule of octane makes eight molecules of CO2) which = 352.

Also the Octane has a weight of 144.

So I took .041g X (352/144)= 0.1


WHat am I missing?
Phys.Org News Partner Science news on Phys.org
Security CTO to detail Android Fake ID flaw at Black Hat
Huge waves measured for first time in Arctic Ocean
Mysterious molecules in space
chemisttree
#2
Mar2-07, 02:31 PM
Sci Advisor
HW Helper
PF Gold
chemisttree's Avatar
P: 3,724
Find out what percentage of gasoline (isooctane) is carbon. Use atomic weight for carbon and hydrogen and formula wt for isooctane.
This is the carbon source for all of the CO2 produced.

The percent of gasoline that is carbon expressed in moles will equal to the moles of CO2.

Also, recheck your formula wt. for isooctane... I get 114.
And... I think the answer is wrong. I get 138 kg or 304 lb.
GCT
#3
Mar13-07, 09:46 PM
Sci Advisor
HW Helper
GCT's Avatar
P: 1,769
Quote Quote by JABEMT View Post
I have the answer to the problem... only my problem is I can figure out how in the world world they came up with it. Here it is... I am sure it a pretty easy equation... only I don't get it!


Calculate the mass of CO2 produced by the combustion of a tank of gasoline. Assume the mass of gasoline is 41.0 kg and that gasoline is pure octane (C8H18); 1 lb =454 g. Express your answer rounded to the nearest whole number. Do not include units with your answer.

Correct answer: 278

I have tried converting the 41.0kg in to grams and got .041g.
I found the atomic mass of CO2 as 44 and X by 8 (research found Every molecule of octane makes eight molecules of CO2) which = 352.

Also the Octane has a weight of 144.

So I took .041g X (352/144)= 0.1


WHat am I missing?
2 C8H18 + 25 O2 = 18 H2O + 16 CO2

molecular mass of Octane is (8x12 + 18) grams/mole

41000.0 grams Octane (1 mole/(114 grams)(16 moles CO2/2 moles Octane)(44 grams CO2/1 mole CO2)=127 kg

Now we're all getting different answers. I used the stoichiometric equation however.

chemisttree
#4
Mar19-07, 11:55 AM
Sci Advisor
HW Helper
PF Gold
chemisttree's Avatar
P: 3,724
Co2 and Octane problem

GCT has it right. The correct answer is 127 Kg or 278 lb.


Register to reply

Related Discussions
Octane + air combustion equation Engineering, Comp Sci, & Technology Homework 1
Fuel Octane Mechanical Engineering 9
Octane Numbers Chemistry 9
Thermal Stress Problem + Tensions Problem Engineering, Comp Sci, & Technology Homework 4
Molar absorptivity of iso octane Chemistry 0