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Dilution and Preparing solutions Standard solution – a solution with a known concentration. 2 Ways to make standard solutions: 1) Dissolve a known mass of solute in a certain volume of solution. 2) Dilute a solution of known concentration. Dilution – procedure for preparing less concentrated solutions from concentrated ones. Eg. How would you prepare a 1L sample of 0.400 M KMnO4 solution from a solution of 1.00 M KMnO4? C = n/V or n = C x V = 0.4 M x 1L = 0.4 mol 0.4 mol of KMnO4 is needed. Find volume of stock solution: CiVi = CfVf C = n/V or NOTICE: V = n/C = 0.4 mol/1.0 M =0.4 L Ci Vi = n and n = CfVf (The Dilution Equation) ***DO NOT USE THIS FOR ANYTHING OTHER THAN A DILUTION SCENARIO!!!*** E.g. You want to prepare 500 mL of 1.75 M solution of H2SO4 from 8.61 M of H2SO4 stock solution. What volume of the stock solution must you dilute? Ci = 8.61 M Vi = ? Cf =1.75 M VF = 500 mL = 0.5 L CiVi = CfVf Vi = CfVf Ci = 1.75 M x 0.5 L 8.61 M = Volume of water to be added = 500 mL – 102 mL = 398 mL 0.102 L p. 386 #51-60 p. 388 #13-18 p. 390 #1-14 p. 399 #1-39 p. 402 #1-28