Devoy Posted July 16, 2011 Share Posted July 16, 2011 (edited) I'm doing an experiment to measure the light absorbance of bromophenol blue? (spectrophotometry) i have 5 test tubes: 1st) 1ml BB and 4ml H2O 2nd) 2ml BB and 3ml H2O 3rd) 3ml BB and 2ml H2O 4th) 4ml BB and 1ml h2O and the 5th) 5ml BB and 0ml H2O. max absorbency at wavelength 595 nm concentration of stock solution: 10mg/L results are: 1st tube: .332 2nd tube: .368 3rd tube: .375 4th tube: .533 5th tube: .746 how can i draw a graph concentration of bromophenol blue (x-axis) and absorbance (y-axis)? then i need to find the absorbance at concentration 2, 4, 6, 8, 10? please i need detailed steps Edited July 16, 2011 by Devoy Link to comment Share on other sites More sharing options...
mississippichem Posted July 16, 2011 Share Posted July 16, 2011 Are those "results" absorbances or extinction coefficients? Link to comment Share on other sites More sharing options...
ewmon Posted July 16, 2011 Share Posted July 16, 2011 i need to find the absorbance at concentration 2, 4, 6, 8, 10? What units? Link to comment Share on other sites More sharing options...
WorldOfBiochemistry Posted July 16, 2011 Share Posted July 16, 2011 Do you have the concentration of the stock solution of BB? I'm doing an experiment to measure the light absorbance of bromophenol blue? (spectrophotometry) i have 5 test tubes: 1st) 1ml BB and 4ml H2O 2nd) 2ml BB and 3ml H2O 3rd) 3ml BB and 2ml H2O 4th) 4ml BB and 1ml h2O and the 5th) 5ml BB and 0ml H2O. max absorbency at wavelength 595 nm concentration of stock solution: 10mg/L results are: 1st tube: .332 2nd tube: .368 3rd tube: .375 4th tube: .533 5th tube: .746 how can i draw a graph concentration of bromophenol blue (x-axis) and absorbance (y-axis)? then i need to find the absorbance at concentration 2, 4, 6, 8, 10? please i need detailed steps Link to comment Share on other sites More sharing options...
John Cuthber Posted July 17, 2011 Share Posted July 17, 2011 Do you have the concentration of the stock solution of BB? "max absorbency at wavelength 595 nm concentration of stock solution: 10mg/L results are: 1st tube: .332 " Link to comment Share on other sites More sharing options...
WorldOfBiochemistry Posted July 19, 2011 Share Posted July 19, 2011 Here are the main steps: 1 - Calculate the concentration of BB on the standards (the 5 tubes you have used). Thhey are just dilutions of the stock solution; 2 - Plot the values of the concentration (usually on x axis) and the values of the absorbance (y axis); 3 - Determine the equation obtained from the linear relationship between concentration and absorbance. In that equation, the x means concentration and the y absorbance. 4 - Substitute in the equation the x for the values of the concentrations you need to, and calculate the absorbance values. I'm doing an experiment to measure the light absorbance of bromophenol blue? (spectrophotometry) i have 5 test tubes: 1st) 1ml BB and 4ml H2O 2nd) 2ml BB and 3ml H2O 3rd) 3ml BB and 2ml H2O 4th) 4ml BB and 1ml h2O and the 5th) 5ml BB and 0ml H2O. max absorbency at wavelength 595 nm concentration of stock solution: 10mg/L results are: 1st tube: .332 2nd tube: .368 3rd tube: .375 4th tube: .533 5th tube: .746 how can i draw a graph concentration of bromophenol blue (x-axis) and absorbance (y-axis)? then i need to find the absorbance at concentration 2, 4, 6, 8, 10? please i need detailed steps Link to comment Share on other sites More sharing options...
John Cuthber Posted July 19, 2011 Share Posted July 19, 2011 The real problem here is that the data are lousy. The 3 highest concentrations are pretty much on a straight line through the origin, but the low concentration ones are odd. They are all too high. Link to comment Share on other sites More sharing options...
CharonY Posted July 19, 2011 Share Posted July 19, 2011 Was a proper blank used? Link to comment Share on other sites More sharing options...
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