Question

There are six glass cups. all of them were filled by 100 mL sample solutions that contain Pb²⁺ ion with unknown concentration. Then into it added successively 0 ml; 0,1 ml; 0,2 ml; 0,3 ml; 0,4 ml; and 0,5 ml standard solutions 10 mg/L Pb²⁺. Table below shows the absorbances measurement of the solution in all six cups.

Volume	0	0.1	0.2	0.3	0.4	0.5
Absorbansi	0.27	0.37	0.53	0.65	0.75	0.68

Calculate the concentration of Pb²⁺ in the above sample if we assume the solution's volume is constant 100 ml.

Answer 1

the unknown solution of pb++ contain 2.342 ppm. It is calculated by constructing the calibration curve for the response of STD added to the sample solution by substracting the absorbance of 0 ml added that means as such sample.