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Topic: Combustion  (Read 725 times)

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Offline Helpmeplease1

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Combustion
« on: January 22, 2019, 07:35:46 PM »
The combustion of octane in excess air can be represented as
C8H18 (g) + 12 1/2O2⟶  8CO2 (g) + 9H2O (g)

To produce 176 g of CO2 in his reaction
A. 1.0 mol of C8H18 needs to react with 25 mol of O2
B. 0.500 mol of C8H18 needs to react with 6.25 mol of O2
C. 0.500 mol of C8H18 needs to react with 3.125 mol of O2
D. 1.0 mol of C8H18 needs to react with 3.125 mol of O2



EDIT: okay! So I think I figured it out... I came up with the answer of B, (see attachment for my working out :)) please let me know if you think I’ve gone wrong somewhere. Thank you!

Ugghhh I’m using an iPad and I’ve been trying to take a photo then shrink it using an app but my image still won’t get accepted and I’m not too sure what to do... :( Anyone else use an iPad or a phone to do this stuff???


« Last Edit: January 22, 2019, 08:50:03 PM by Helpmeplease1 »

Offline billnotgatez

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Re: Combustion
« Reply #1 on: January 22, 2019, 07:57:37 PM »
You have to show your attempts or thoughts at solving the question to receive help.
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Offline Helpmeplease1

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Re: Combustion
« Reply #2 on: January 22, 2019, 08:13:57 PM »
You have to show your attempts or thoughts at solving the question to receive help.
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[


Oops, sorry.  :-\ I’m trying to figure out how to post an image
I haven’t done this for about half a year and I’ve forgotten most of this, but what I ve got so far is that if I have 176g of CO2, then I’d have 44M and 4mol so then I’d also have 4 moles of C8H18, but then wouldn’t I also have 4 moles of O2? But that doesn’t seem right, so I’m a bit confused.

I’m extremely rusty on this thing. Could you maybe give me the name of what these calculations are called so I could possibly find a simple YouTube video please? :)

Offline billnotgatez

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Re: Combustion
« Reply #3 on: January 22, 2019, 08:26:08 PM »
When you are editing a post
there is a link at the bottom of the page
Quote
+ Additional Options...
clicking on the plus sign will give you more options to post images.

Offline Borek

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Re: Combustion
« Reply #4 on: January 23, 2019, 02:42:13 AM »
Hard to comment on your work not seeing it, but B is the correct answer.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Offline Enthalpy

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Re: Combustion
« Reply #5 on: January 23, 2019, 06:03:47 AM »
[...]I haven’t done this for about half a year and I’ve forgotten most of this [...]
When I was a student, a math professor used to answer to this:
"My course is long ago. Yours is not."
Now I see what he meant.

If you can forget how to balance a reaction, then there is something fishy in the way you learn. I don't even really see what should be learnt here.

By the way, your reaction equation for burning octane is wrong.

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