posted by cristy on .
A student weighs out a 14.0 g sample of Fe(NO3)2, transfers it to a 500 mL volumetric flask, adds enough water to dissolve it and then adds water to the 500 mL tic mark.
What is the molarity of iron(II) nitrate in the resulting solution?
Calculate the molar mass of Fe(NO3)2 (F)
number of moles of Fe(NO3)2 = 14.0 g/F
If the number of moles were dissolved in 1 L the molarity would be
14.0/F mol L^-1
but this is in only 500 ml so the concentration is
(14.0 x 1000)/(F x 500)
i.e. twice the concentration if the final volume had been 1 L.