Question

attempt SOUD ork - A... P4 18 Review Homework StatCrunch Do Homework - A... his Course Qui estion 47 Consider the following calibration curve for Cu2+ ion: 1 t yet swered nts out of 10 7 09 y = 0.99x -0.011 Flag 0.8 13 estion 0.7 0.6 19 Absorbance 0.5 0.4 25 0.3 0.2 31 01 O 37 0 0 0.1 0.2 0.3 0.7 0.8 0.9 1 0.4 0.5 0.6 Cu?'), mg/ml 43 49 If the average absorbance of a diluted unknown Cu salt is 0.650, the (Cu) in the diluted unknown salt is mg/mL. Finish Time le Select one: O A. 0.650 OB. 1.50 OC. 0.660 OD. 0.668 O E.0.990 G Search or type URL

Answer 1

Answer = option D

0.668 mg/ml

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From the plotted calibation line graph the concentrations of unknown $Cu^{2+}$ can be ascertained.

The regression equation fro the above graph is given as ---

$y=0.99x-0.011$

It is of the form y = mx-c with negaive intercept on absobance axis.

y = absorbance axis ( data)

x = concentration of $Cu^{2+}$ in mg/ml

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$y=0.99x-0.011$

given that y = 0.650

X = ?

Substitute for y and determine x from the regression equation ( this is usually done from calibated curves in instrumentation laboratories )

$y=0.99x-0.011$

0.650 = 0.99 x- 0.011

x = 0.6676 mg/ml

= 0.668 mg/ml

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From a fine divisions graph the same can be ascertained from graph also.