EXPERIMENTAL PROCEDURE the st or Check out volumetric a 10.00 mL pipet from Part
ID: 488927 • Letter: E
Question
EXPERIMENTAL PROCEDURE the st or Check out volumetric a 10.00 mL pipet from Part C from your instructor Part A mast be done before Part B can be done. can be done before or Pares A and B wear gloves for all parts of the procedure. A Peparetion of H,C,o, solution (CAUTION: PorsoNous) NOTE: YOUR ENTIRE EXPERIMENT DEPENDS ON THIS SOLUTION BEING MADE CORRECTLY acid. H Co., will be used as the reducing agent to standardize your no, solution. Using the analytical balance, weigh approximately 0.20 g H CO, 2 H,0 into your clean, dry 50 ml beaker. CAUTION OXALIC ACID ISPOISONOUS. Add about 20 mLof DI water to the beaker, stir to dissolve the solid, and transfer the solution to your cean 50.00 mL volumetric flask. Rinse the beaker with another 10 mL DI water and pour that into the volumetric flask. Use a wash bottle to rinse all portions of the HzCao, solu- tion into the volumetric flask. Fill the flask to the volumetric mark on the neck, stopper, and invert several times to mix thoroughly. B. Standardization of KMno. 2. Have one of your large beakers to use as a waste container as you do this experiment. None efthee reacents should be discarded down the sink. Set up a ring sand, ring support, and Bunsen burner, as you need to heat the reactions below. Use your clean, dry 100 mL beaker to obtain about 70 mL of the prepared no solution. 4. Clean three 125 or 250 mLErlenmeyer flasks and the 10.00 mL pipet, and rinse each with DI water. Rinse the pipet with your H Co solution, and then pipet a 10.00 mL portion into each of the Erlenmeyer flasks. To each flask, add 20 mL DI water and 10 mL of 3 M Haso. using a graduated cylinder for measurement. inse your buret with the permanganate solution, and then fill the buret. Record the initial volume of KMno. in the buret. (Note: Because of the dark color of permanganate solution, you need to read the top of the menis cus instead of the bottom.) Use the burst to quickly add about 8 mL of the KMno titrant to the first H,Cao sample with mixin The solution should be purple at this point. You do g. volume not need to record this intermediate from the buret, but do not use any more of the titrant until Step 7Explanation / Answer
From the data set
A. preparing H2C2O4 solution
mass of H2C2O4.2H2O = 0.201 g
volume of solution = 50 ml
molarity = 0.201/90.03 x 0.05 = 0.045 M
B. standarization of KMnO4
trial #1
Volume H2C2O4 = 10 ml
moles H2C2O4 = 0.045 M x 10 ml = 0.45 mmol
volume KMnO4 = 13.74 ml
molarity KMnO4 = 0.45 x 2/5 x 13.74 = 0.013 M
C. Iron(II) unknown concentration
mass of unknown = 0.430 g
Volume KMnO4 = 18.74 ml
moles KMnO4 = 0.013 M x 18.74 ml = 0.244 mmol
mass Iron(II in sample = 0.244 mmol x 5 x 55.845/1000 = 0.068 g
% Iron in sample = 0.068 x 100/0.430 = 15.84%
Similarly calculations for other trial runs can be done.
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