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Topic: gravimetric analysis  (Read 6614 times)

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Offline aushy

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gravimetric analysis
« on: February 12, 2009, 04:04:03 AM »
This question has me stumped..

A .500 g sample of sodium sulfate (Na2SO4) and a .500 g sample of aluminium sulfate (Al2(SO4)3 were dissolved in a volume of water and excess barium chloride added to precipitate barium sulfate. What was the mass of barium sulfate produced?

How would I go about answering this?

Thanks,
aushy
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Offline AWK

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Re: gravimetric analysis
« Reply #1 on: February 12, 2009, 04:09:48 AM »
This is a simple stoichiometry. Write down abalanced reaction, then start calculations

http://www.chembuddy.com/?left=balancing-stoichiometry&right=ratio-proportions
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Offline aushy

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Re: gravimetric analysis
« Reply #2 on: February 12, 2009, 04:14:28 AM »
I guess my problem is that I don't know what the equation would be :S
Isn't there another way that it could be done without a full equation? I thought perhaps you could assume that the product would be 4BaCl (considering there are 4 mole of sulfates reacting)
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Offline Borek

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Re: gravimetric analysis
« Reply #3 on: February 12, 2009, 04:38:39 AM »
What is formula of the barium sulfate?
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Offline aushy

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Re: gravimetric analysis
« Reply #4 on: February 12, 2009, 04:44:25 AM »
Quote from: Borek on February 12, 2009, 04:38:39 AM
What is formula of the barium sulfate?

The question i wrote was word for word the question they gave us, so I'm not entirely sure. But im assuming BaSO4

** Oh and i just realised in my post above i wrote 4BaCl, i meant 4BaSO4 **
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Offline Borek

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Re: gravimetric analysis
« Reply #5 on: February 12, 2009, 04:54:06 AM »
OK.

What is net ionic equation of the reaction?
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Offline aushy

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Re: gravimetric analysis
« Reply #6 on: February 12, 2009, 04:58:15 AM »
Quote from: Borek on February 12, 2009, 04:54:06 AM
OK.

What is net ionic equation of the reaction?

Once again, not too sure. Isn't that something that you should be telling me?

By the way, thanks for your time everyone :)
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Offline Borek

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Re: gravimetric analysis
« Reply #7 on: February 12, 2009, 05:02:02 AM »
Quote from: aushy on February 12, 2009, 04:58:15 AM
Once again, not too sure. Isn't that something that you should be telling me?

No, it is something that I am trying to draw from you.

I am leaving in about 20-30 minutes, so you better hurry.
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Offline aushy

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Re: gravimetric analysis
« Reply #8 on: February 12, 2009, 05:07:15 AM »
Im not too sure what it is lol.
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Offline Borek

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Re: gravimetric analysis
« Reply #9 on: February 12, 2009, 05:13:59 AM »
You have not learnt about net ionic reactions yet?

OK. Earlier you wrote something that suggested you can be on the right track. There will be as many moles of BaSO4 in products as there moles of SO42- in reactants.
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Offline aushy

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Re: gravimetric analysis
« Reply #10 on: February 12, 2009, 05:18:27 AM »
So am i right in assuming that the ratio will be 1:Na2SO4 : 1Al2(SO4)3 : 4BaSO4? Or Will it work if i work out the number of moles of sulfate ions in both the two samples, and add those moles together to get the mole of BaSO4?
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Offline Borek

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Re: gravimetric analysis
« Reply #11 on: February 12, 2009, 05:25:08 AM »
Quote from: aushy on February 12, 2009, 05:18:27 AM
Will it work if i work out the number of moles of sulfate ions in both the two samples, and add those moles together to get the mole of BaSO4?

That's the correct approach.
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Offline aushy

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Re: gravimetric analysis
« Reply #12 on: February 12, 2009, 05:29:15 AM »
Ohhh awesome! Thanks heaps for that. That will really help me on my test tomorrow!
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