Question

1,2,3

BEER'S LAW - PRE-LAB QUESTION 1. What mass of solid CoCl2 would you need to prepare 250 mL of 0.150 M solution of CoCl2 from solid CoCl2 and distilled water? Show your calculations. 2. Using the solution from the previous problem and distilled water, how would you prepare 100 mL of a 0.060 M solution of CoCl2? (Hint: use the dilution formula) 3. What is Beer's law? Write an equation and describe all terms used in it.

Answer 1

1 V2 = volume of dilute I solution - 100ml 1. 250 ml of 0.150M Colle solulion = (250 x0150 ) mol.cockz [Molar mass of cocl2 = 129,8399] 1000 (0.150 x129.839)g cockz .". Mass of solid colle needed =4.8699 (Ang) = 4:869 g Coche 2. V, G = V2 C2 Vi = volume of original og Vix 0.150 M = 100 ml x 0.060 M a = 0.150 M V solution needed on Vi = (100% 0.060) mL in = 40 mb I C2 = 0.060M - In a 100 ml volumetric flask take 40ml of original stock so and dilute it by distilled water to the mark. Then make the solution homogesteous by shaking it properly. 3. Beer's Law & Beer's Law states that the rate of decrease in intensity of radiation absorbed is proportional to the intensity of radiation and to the concentration of the solute. Mathematical expression ; log ( 10 )= €.eil [ Io = Intensity of incident light Io = os of transmitted 99 € = Molas esetinction coefficient e = Molar concentration of solulé e = Length of the photo-cell or optical path I