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Title: How to calculate the molarity of a solution with molecular weight of 222 g/mol? Post by: micro123 on Sep 23, 2012 A molecule has an extinction coefficient ? of 1.80 for a 1% solution, and has a molecular weight of 222 g/mol.
The absorbance is 0.40. What is the molarity of this solution (expressed in mM)? (The answer is 10 mM, but I?m not sure how to get there. I calculated the concentration to be 0.22.) Can anyone help me figure this out? Title: How to calculate the molarity of a solution with molecular weight of 222 g/mol? Post by: rjavier1 on Sep 23, 2012 Content hidden
Title: How to calculate the molarity of a solution with molecular weight of 222 g/mol? Post by: Fiolet on Sep 23, 2012 use Beer-Lambert Law
A = E b c where E is the wavelength-dependent molar absorptivity coefficient with units of M-1 cm-1. A = is absorbance b is the path length which = 1cm, and c is the analyte concentration 0.4 = 1.8 * 1 * C C =0.222 M =222 mmole/litre you have 1% sol supose it 1gm in 100of sol so in 1000 = 0.1 moles of solute = 0.1/222=0.00045mol =0.45 mmol 0.45 mmol* 22.2 mM = 9.99mM |