Question

A 6.26 g sample of a solid containing ni is dissolved in 20.0 ml water. a 5.00 ml aliquot of this solution is diluted to 100.0 ml and analyzed in the lab. the solution was determined to contain 5.28 ppm ni. determine the molarity of ni in the 20.0 ml solution.

Answer 1

Concentration of Ni in 20mL = 5.28ppm x dilution factor = 5.28 x 100/5 = 105.6 ppm = 105.6 mg/L 

molar mass of Ni = 58.6934 g
Molarity of Ni = 100.40 x 10^{-3} / 58.6934 = 1.71 x 10^{-3} M = 1.71 mM.