Question

b) How many mLs of an aqueous 0.1502 M HCl solution are needed to be added to completely precipitate all of the Pb? ions from 20.00 mL of an aqueous 0.100 M leader nitrape solution? 2 013. So c) How would a chemist correctly make 50.00 mL of an aqueous 1.500 x 102 M La(NO3)3 solution from an aqueous 0.500 M La(NO3)3 solution? wwed bud ei na siwedd li 6) (19 pts) What is the Molarity (after mixing) of the Cr ions in solution when 25.00 ml of an aqueous 1.055 M KCl solution is mixed with 50.00 mL of an aqueous 0.6245 M BaCl2 solution? T and P are normal and constant; volumes are additive. hm260XJOO

Answer 1

Answer PbO2 Balanced reaction: Pb2+ + 2 ct Pb (Precipitate) loans According to balanced equation, 2 moles of cir are needed to completely precipitate 1 mol of I mol of Pb2+ ion. Molarity = number of moles of salute Volume of solution in Liter volume of soluti 20.00 mL of 0-100 (M) Pb(NO3)2 = 20.00 x 0-100 moles of 1000 Pb(NO) 20.0080-100 moles of 1000 Pb²+ = 0.002 moles of Pb 2+ Let's assume V mL of o.1502 M He is needed for complete precipitation. Moles of co- needed - VXO. 1502 moles. 1000 = 0.002 ( 44006502) - 0.002 VX0-1502 1000 a = 26.63 0. 1502 M Hel is needed Hence 26.63 ml of aqueous

(6) According to dilution law- evi = C2 V2 C, and ca are initial and final concentrations respectively Vi and ₂ are initial and final volumes respectively. Here , = 0.550M 9 C₂ = 1.500x 10 m V₂ = 50.00 mL C2 V2 W = Ci 1.500 x 102 x 50.00 mL 0.500 = 1.50 mL Hence, take one 50 mL volumetric flask. Place 1.50 mL of 0.500 M La(NO3)3 solution into it through a Pipette. Then add water to fill the flask upto 50 mL Calibration mark. Thus, 50.00 mL aqueous 1.500x102 M La(NO3)3 solution can be prepared correctly