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Beer's Law

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zzzzz:
How do you rearrange the ideal gas law to give an equation relating pressure to concentration and then using that to modify Beer's Law to apply to gas pressures, rather than concentrations? Also, what's the formula that relates absorbance to gas pressure?

Borek:
Show us the equations, show us what you have tried, show us where you are stuck.

zzzzz:
well the ideal gas law is PV=nRT and Beer's Law is A=Ebc. I don't know how to set it so pressure relates to concentration. P=nRT/V=nRT(1/V), but how does that relate to concentration? So does P=MRT? Then would P=A/Eb*(RT)? If so then how does absorbance related to gas pressure?

Borek:
Hint: amount of energy absorbed is directly proportional to number of particles present in the sample volume. In case of ideal gas if you increase pressure twice, number of particles in the sample volume also increases twice, which is equivalent of increasing concentration twice.

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