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(5 € HW12B-due-Nov-17 × | e Search Textbook Solutions I + () |(Dezto.mheducation.com/hm.tpx 2 1 attempt left Check my work Be sure to answer all parts Report problem The recommended procedure for preparing a very dilute solution is not to weigh out a vcry small mass or measure a very small volume of stock solution. Instead, it is done by a series of dilutions. Hint A sample of 0.7541 g of KMn04 was dissolved in water and made up to the volume in a 500.0 mL volumetric flask. A 2.000 mL sample of this solution was transferred to a 1000 mL volumetric flask and diluted to the mark with water. Next, 10.00 mI. of the diluted solution was transferred to a 250.0-mL nask and diluted to the mark with water (a) Calculate the concentration (in molarity) of the final solution. Enter your answer in scientific notation. (b) Calculate the mass of KMnO4, needed to directly prepare the final solution. Enter your answer in scientific notation Type here to search 11/17/20172Explanation / Answer
a)
Final solution molarity
molo = mass/MW = 0.7541 / 158.034 = 0.00477
C1 = mol/V= 0.0047/0.5 = 0.0094
now,
C2 = 0.0094 M, V2 = 2 mL
C3 = X V3 = 1000 mL
C3 = 2/1000*0.0094 = 0.0000188 M
then... we use
C4 = 0.0000188 M, V4 = 10 mL
C5 = X V5 = 250 mL
C5 = 10/250*0.0000188 = 7.52*10^-7 M
b)
KMnO4 needed t oprepare final mix
mol = C*V = 250* 7.52*10^-7 = 0.000188
mass = mol*MW = 0.000188*158.034 = 0.02971 g or 29.71 mg --> 2.97*10^-2 g
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