A solution is prepared by mixing 150 g of sodium citrate (FW = 294g/mol) to a total volume of 500 mL. A second reagent is prepared by using 10 mL of this and making a total volume of 50 mL. What is the molarity and %W/V of each solution.
First Solution:-
Mass = 150g
Molar mass = 294g/mol
Moles = mass/molar mass = 150g/294g/mol = 0.510moles
Volume = 500mL = 500/1000L = 0.5L
Molarity = moles/Volume in L = 0.510moles/0.5L = 1.02M
%W/V = mass in grams / volume of solution = 150g/500mL = 0.3 or 30%
Second solution
10mL of first solution is used so,
Molarity = 1.02M
Volume = 10mL = 10/1000 = 0.01L
Moles = Molarity*Volume = 1.02M*0.01L = 0.0102moles
Volume of the solution = 50mL = 50/1000 = 0.05L
Molarity = moles/Volume = 0.0102moles/0.05L = 0.204M
Mass of the solute = moles*molar mass = 0.0102moles*294g/mol = 2.999g
%W/V = 2.999/50 = 0.059 or 5.9%
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