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Topic: Sulphuric Acid Calculation  (Read 7078 times)

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Offline thomas49th

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Sulphuric Acid Calculation
« on: June 11, 2007, 03:33:47 PM »
2S + 2H2O + 3O2 -> 2HSO4

Calculate the number of moles of sulphuric acid that could be made from 1 tonne of sulphur (1 tonne = 1000000g)

RAM S = 32, O = 16, H = 1

I first tried writing 64g of S produceds 196g of Sulphuric Acid

So I devied 196 by 64 to get 3.0625, which is then multiplied 1000000 by to get 3062500g. I then used the equation number of moles = mass in g / relative molecular mass
giving me 15625moles. It that right?

Offline enahs

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Re: Sulphuric Acid Calculation
« Reply #1 on: June 11, 2007, 05:14:46 PM »
No.

And you are making it more complicated then you have to.
Look at your balanced equation!
If you start with 1 mole of sulfur, you get 1 mole of sulfuric acid, 2 moles of sulfur 2 moles of sulfuric acid, 3-3,4-4, n-n.

The number of moles of sulfur in 1,000,000g = number of moles of sulfuric acid produced, using stoichiometry.

Offline Borek

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Re: Sulphuric Acid Calculation
« Reply #2 on: June 11, 2007, 05:25:45 PM »
And you are making it more complicated then you have to.

He uses ratio approach - and it doesn't matter whether you convert to moles first, or convert to moles last. Sure, converting to moles first is quicker, but the general idea is OK.

If only he had this equation properly balanced... ;)
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Offline enahs

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Re: Sulphuric Acid Calculation
« Reply #3 on: June 11, 2007, 05:30:51 PM »
He uses ratio approach - and it doesn't matter whether you convert to moles first, or convert to moles last. Sure, converting to moles first is quicker, but the general idea is OK.

Tis' true. But going straight to the answer just seems to much easier to me. Also, you do not introduce any error (which is I think what happened with how he was working it) when adding up the molecular weight of sulfuric acid, or round off error, etc.

Quote
If only he had this equation properly balanced... ;)
See, I made the same mistake I always made in GenChem, assuming the equation I was given was already balanced. I always thought it was annoying of my teachers, ahh well. I am a tard, move along, nothing to see here, except the obvious which I can not see!

Offline Borek

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Re: Sulphuric Acid Calculation
« Reply #4 on: June 11, 2007, 05:38:24 PM »
Not to mention wrong formula of sulfuric acid ;)
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Offline enahs

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Re: Sulphuric Acid Calculation
« Reply #5 on: June 11, 2007, 05:53:47 PM »
Not to mention wrong formula of sulfuric acid ;)

hah hah hah hah, I am such an idiot. I guess I just like skipping all the work, as a balanced equation or knowing the formula for sulfuric is not even required, as long as you know there is only one S atom in sulfuric acid (and you are asked the question how it is worded with the given information). I guess when trying to help out in the high school forum I will not just use such shortcuts and skips and such. I am such a jackhole.

Offline Borek

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Re: Sulphuric Acid Calculation
« Reply #6 on: June 11, 2007, 06:09:32 PM »
Try my EBAS - and I am no joking. It does part of the thinking for you ;)
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Offline enahs

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Re: Sulphuric Acid Calculation
« Reply #7 on: June 11, 2007, 06:22:08 PM »
Try my EBAS - and I am no joking. It does part of the thinking for you ;)

Well, clearly I have either forgot how to think, or am just really tired and stressed out from work, either way it means I need to practice.

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