[McCoy]

A brass sample containing ~5% lead in the morning is given. It's required that a mass of alloy sample required to produce 100ml of solution which has an absorbance of 0.4 be calculated.How do you go about it? I'm confused.I've tried to calculate Transmittance so that I can determine the concentration responsible for the absorbance of 0.4 but i got stuck from there.T=1/(10^0.4),but it seems it's not useful.So A=a.b.c,I can assume b=1 but there's no a. what's the the other way of going through this please? I'd appreciate your help.

[Arkcon]

Well, breaking apart your particular jargon, you have to determine a certain mass, to give an absorbance of 0.4.  But you don't have the constant, the extinction coefficient.  Yes?  Maybe if you have some standards, and you're within the linear range, you can do without it?

[McCoy]

yes I've  1000ppm lead as a standard solution and  I have to assume that beer's law is obeyed.I can't 'see' how that standard soution is going to help me though.
Thanks

[McCoy]

Oh I got it.Thanks to everyone who was about to reply.