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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: webassignbuddy on September 12, 2013, 09:24:14 PM

Title: Quick quick quick help needed with finding the percent difference of these 2?
Post by: webassignbuddy on September 12, 2013, 09:24:14 PM

Problem:

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fi11.photobucket.com%2Falbums%2Fa179%2Fslourg%2FCHEMISTRYHELP_zpsa0f9e2e3.png&hash=9611d5984e3206e4a98dde4086908925b3fb4ace)

Tables Needed:

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fi11.photobucket.com%2Falbums%2Fa179%2Fslourg%2FINLAB-Cu2SolidTable_zpse6df4e1d.png&hash=dfcb989915e366d744d7421fe3dcec85c621d251)
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fi11.photobucket.com%2Falbums%2Fa179%2Fslourg%2FINLAB-Cu2StockSolutionTable_zpsa074dc96.png&hash=7e460a802e3e68b7c91241bc90bc8aa626b45870)

My calculations:

% difference for absorbance (SOLID) = [(0.336 theoretical - 0.385 nm actual) x 100%]/0.336 theoretical
% difference for absorbance (SOLID) = (-0.049 x 1)/0.336 theoretical
% difference for absorbance (SOLID) = -0.146 (INCORRECT - 2/3 submissions)

% difference for absorbance (STOCK SOLUTION) = [(0.336 theoretical unknown - 0.962 nm actual) x 100%]/0.336 theoretical
% difference for absorbance (STOCK SOLUTION) = (-0.626 x 1)/0.336 theoretical
% difference for absorbance (STOCK SOLUTION) = -1.86 (INCORRECT 3/3 submissions)

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% difference for concentration M (SOLID) = (0.102 M theoretical - 0.117 M actual)/0.102
% difference for concentration M (SOLID) = -0.015/0.102
% difference for concentration M (SOLID) = -0.147 (INCORRECT - 1/3 submissions)

% difference for concentration M (STOCK SOLUTION) = (0.102 M theoretical - 0.304 M actual)/0.102
% difference for concentration M (STOCK SOLUTION) = -0.202/0.102
% difference for concentration M (STOCK SOLUTION) = -1.98 (INCORRECT - 1/3 submissions)

The values in blue were taken from my 2 In-Lab tables but for some reason, webassign is marking all of them as wrong!

Title: Re: Quick quick quick help needed with finding the percent difference of these 2?
Post by: Borek on September 13, 2013, 02:40:01 AM

Quote from: webassignbuddy on September 12, 2013, 09:24:14 PM

% difference for absorbance (SOLID) = -0.146 (INCORRECT - 2/3 submissions)

And not -14.6%?