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1-Calcium can be determined by reaction with arsenazo( III) to form violet complex (λmax = 590)....

1-Calcium can be determined by reaction with arsenazo( III) to form violet complex (λmax = 590). A series of standard solutions of calcium were prepared and measured specrophotometricaly against reagent blank, the results are shown in the table below. if 5 ml of calcium sample is treated as standard solution in 25 ml measuring flask and had absorbance of 0.512. Calculate the calcium concentration at the sample?

14 x 10-5    10 x 10-5     6 x 10-5     2 x 10-5    concentration

0.985 0.698    0.416             0.142    absorbance

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