Into a 50.00mL volumetric flasks were pipetted 10.mL aliquots of a natural water sample. Exactly 0.00, 5.00, 10.00, 15.00 and 20.00mL of standard addition solution containing 11.1 pp of Fe were added to each, followed by an excess of thiocyanate ion to give the read complex Fe(SCN).
After dilution to volume, the instrument response was measured with a colorimeter for each of the five solutions. The responses were found to be .240, .437, .621, .809, and 1.009
a)what is the concentration of Fe in the water sample?
b)what is the standard deviation of the concentration of Fe?