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Topic: how does 0.2ml of a 0.02N sulphuric acid soln =0.02%?  (Read 9758 times)

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Offline j22rober

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how does 0.2ml of a 0.02N sulphuric acid soln =0.02%?
« on: September 11, 2011, 06:57:52 PM »
Show mathematically how 0.2ml of a 0.02N sulphuric acid solution is equivalent to 0.02%?

If I convert my concentration to molarity (0.01M) and my volume to L (2x10^-4) then I can calculate the moles to give me 0.02....but this is not a percent. I am open to suggestions on this. Thanks.

Offline Dan

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Re: how does 0.2ml of a 0.02N sulphuric acid soln =0.02%?
« Reply #1 on: September 12, 2011, 03:25:39 AM »
If I convert my concentration to molarity (0.01M) and my volume to L (2x10^-4) then I can calculate the moles to give me 0.02

I agree with 0.01 M, but how you got 0.02 mol from there I don't know.

Remember, M = mol/L. A concentration of 0.01 M means 0.01 mol in one litre.
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Offline AWK

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Re: how does 0.2ml of a 0.02N sulphuric acid soln =0.02%?
« Reply #2 on: September 12, 2011, 05:19:23 AM »
Volume in not important for concentration conversions. Since 0.01 N is a very diluted acid then you can use density of water for calculations.
0.01 N = 0.005 M => 0.005 mole /1000 g ~ 0.5 g /1000g = 0.05 %
Mole H2SO4 = 98 ~ 100
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Offline Borek

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Re: how does 0.2ml of a 0.02N sulphuric acid soln =0.02%?
« Reply #3 on: September 12, 2011, 05:23:18 AM »
Show mathematically how 0.2ml of a 0.02N sulphuric acid solution is equivalent to 0.02%?

Question as worded makes no sense. 0.02% of what?
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Offline j22rober

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Re: how does 0.2ml of a 0.02N sulphuric acid soln =0.02%?
« Reply #4 on: September 12, 2011, 07:45:52 PM »
Ok, I spoke to my teacher about this question today. Which was written as above in my assignment. Apparently I have to calculate the mass (g) of the sulfate ion (SO4) from this information. Where MW =  96.06g/mol, v=0.0002L, C=0.01mol/L. Combining C=N/V and N=m/MW gives: m=CxVxMW = 0.000192g which is ~ 0.0002g. Apparently I have a 1.0g (new info given to me today) sample containing  the 0.0002g. So if I have a 100g sample there is 0.02g in it. By weight percent (w/w)= (0.02g/100g)x 100% = 0.02%.

This is how I was supposed to solve it...who knew? Especially with the missing information.


Offline AWK

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Re: how does 0.2ml of a 0.02N sulphuric acid soln =0.02%?
« Reply #5 on: September 13, 2011, 07:51:03 AM »
MW =  96.06g/mol
Why sulfate?
Your question concenrns sulfuric acid!
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