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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: eaglesfn68 on October 05, 2010, 07:10:13 PM

Title: beers law plot
Post by: eaglesfn68 on October 05, 2010, 07:10:13 PM

hello everyone, i need to do a beers law plot. i got the percent transmittance which i converted to absorbance but im not sure how to get the molar concentration.

i found the max wavelength to be 515 nm. I prepared three 8-10ml diluted solutions by mixing a standard solution x (0.100M) and distilled water in ratios of 3:1(6ml standard solution, 2ml water),1:1(5ml of standard solution, 5ml water), and 1:3(2ml standard solution, 6ml water). i measured the absorbance of each of these diluted solutions and the max wavelength and got

3:1 diluted solution  0.294
1:1 diluted solution  0.466
1:3 diluted solution  0.143

i know that molarity = (moles of solute)(liters of solution)

how do i know what the liters of solution is and the moles of solute?

Title: Re: beers law plot
Post by: Borek on October 06, 2010, 03:02:18 AM

http://www.chembuddy.com/?left=concentration&right=dilution-mixing

Title: Re: beers law plot
Post by: eaglesfn68 on October 06, 2010, 04:06:08 PM

i know who to do dilution calculations im just not sure what the volume of each solution is

Title: Re: beers law plot
Post by: Borek on October 06, 2010, 04:50:58 PM

Have you tried to add volumes of solutions mixed?

Title: Re: beers law plot
Post by: eaglesfn68 on October 06, 2010, 06:30:58 PM

i know that these solutions have 8ml,10ml,and 10ml respectively but when i graph i dont seem to get a straight line which i know i should.

3:1 diluted solution 
1:1 diluted solution 
1:3 diluted solution