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Topic: AA Spectrophotometry  (Read 6771 times)

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Offline ixi

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AA Spectrophotometry
« on: April 21, 2008, 05:52:26 PM »
In lab using AAS we did an experiment with Fe. We made 5 solutions and an unknown. The problem is to find out what the concentration of the unknown is.

Our results were

Concentration    Result
0.02                 0.016
0.04                 0.027
0.06                 0.039

and the unknown is 0.034

could i find out what the concentration is through a ratio?
(0.04/0.027)=(x/0.034)
x= 0.05

is that right?

Offline Arkcon

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Re: AA Spectrophotometry
« Reply #1 on: April 21, 2008, 05:57:31 PM »
Usually, when you have more than two points, they'd like you to plot a line, and determine a relationship between absorbance and concentration that uses all points.  Did anyone mention how you were to do that?  In your ratio, you're only using one point -- can you really be so sure it's correct, that you don't need any others?

P.S. You said you made 5 solutions, but you only posted 3.  You not ignoring the others, because you don't link them or think you don't need them because they're far from the unknown absorbance, are you?
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline ixi

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Re: AA Spectrophotometry
« Reply #2 on: April 21, 2008, 06:30:54 PM »
No, I didn't post them cause I was kinda lazy, lol. But my data is correct and I did graph them on excel and it was very close to a straight line.

Concentration    Result
0.02                 0.016
0.04                 0.027
0.06                 0.039
0.08                 0.047
0.10                 0.058

Unknown -- 0.034

How would I find out the concentration then? On excel the equation for the line is
y = 0.5185x + 0.0068

Would I find out the concentration from that somehow?

Our prof didn't tell us how we were to find it, just that we were.

Offline Borek

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Re: AA Spectrophotometry
« Reply #3 on: April 21, 2008, 06:56:14 PM »
What is x, what is y - how do they relate to the concentration and signal? Can you put known signal into that equation and solve for the concentration?
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Offline ixi

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Re: AA Spectrophotometry
« Reply #4 on: April 21, 2008, 07:34:31 PM »
x is the concentration

so would it be

0.034= 0.5185x+0.0068
x= 0.0524

Offline ARGOS++

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Re: AA Spectrophotometry
« Reply #5 on: April 21, 2008, 07:39:46 PM »
Dear ixi;

That’s correct!

Good Luck!
                    ARGOS++


Offline ixi

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Re: AA Spectrophotometry
« Reply #6 on: April 21, 2008, 07:46:06 PM »
awesome

thanks for the help :)

Offline ARGOS++

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Re: AA Spectrophotometry
« Reply #7 on: April 21, 2008, 08:01:40 PM »
Dear ixi;

You’re welcome!   ─   Soon again.


Good Luck!
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