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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: PaintYourFuture on March 30, 2012, 11:42:04 PM

Title: AAS prac sample prep question
Post by: PaintYourFuture on March 30, 2012, 11:42:04 PM

The prac is to determine the amount of lead in a brass sample, and we are to calculate how much sample to use (I'm not sure of this bit- what's going on, and how to perform the calculation). The sample contains approx. 5% lead.

'Calculate the mass of alloy sample required to produce 100mL of solution whose absorbance due to lead is approximately 0.4.'

Title: Re: AAS prac sample prep question
Post by: JustinCh3m on March 30, 2012, 11:54:53 PM

use Beer's Law to determine the concentration in mol/L.  You have 0.100L of solution which allows you to calculate moles of the alloy.  Since you know the percent Pb in the alloy, do you know how to get moles and then grams of Pb (lead)?...

Title: Re: AAS prac sample prep question
Post by: PaintYourFuture on March 31, 2012, 01:51:48 AM

Thank you! That's starting to make a little sense..although what molar absorptivity coefficient would I use, and do I assume path length 1cm?