Question

Determine the equilibrium concentration of FeSCN2+ in each solution. (Page below are the initial concentrations of FE3+ and scn- for each solution )

Secondly, use stoichiometry to determine equilibrium FE3+ and SCN -. ( concentration used for FE and KSCN are both 0.002M )

the absorbance of each standard in the same test tube used to blank the spectrophoto standards from least to most concentrated, rinsing with a small amount of the next sta tilling the test tube. Record absorbance values and observations in your notebook. meter. Measure Part B: Determining the Equilibrium Constant Obtain 20 mL 0.002 M Fe(NOb in l M HNO3 İn a clean, dry 50 trom above. Prepare the following solutions with Mohr or volumetric pipets into large, labeled test mL beaker. Use the same KSCN tube. Assume the volumes are additive. 0.002 M Fe(NOs) 0.002 M NO3 Solutionin 1 MH Solution 5 Solution6 Solution 7 5.00 mL 5.00 mL 5.00 mL KSCN DI H20 1.00 mL 4.00 mLlo 3,00 mL 2.00 mL TomL Obtain absorbance values for each solution by transferring each solution, one at a time, into the small test tube used previously. Fill each test tube to ' full, wipe the test tube dry with a Kimwipe, then record the absorbance value from the spectrophotometer. In order to ensure no change in the concentration of the solution you are measuring, rinse the small test tube with a small amount of the solution to be measured before filling. WASTE DISPOSAL AND CLEANUP All solutions must be placed in the aqueous waste container in the fume hood. Empty and clean all test tubes and other glassware thoroughly before returning to storage. DATA ANALYSIS Do not forget to show work (ICE table!), include units, and show appropriate significant figures Part A: Preparing the Standard Curve the stock solution. 1. Determine the concentration of FeSC 2. Determine the concentration of FeSCN2* in standards 1-4 3. Construct a graph of absorbance versus concentration for standards 1 -4. Remember to include the title, axis labels, data points, best fit line, and r' value. Part B: Determining the Equilibrium Constant 4. Determine the initial concentration of Fe3 and SCN in each equilibrium solution 5. Determine the equilibrium concentration of FeSCN2* in each solution (standard curve 6. Use stoichiometry to determine the equilibrium [Fe ] and [SCN-] 7. Calculate the equilibrium constant for Solution 5 7 8. Obtain equilibrium constants for Solutions 5-7 from another grou 9. Perform a Q-test on the most likely outlier 10. Determine the average value for Keg for all statistically significant trials 11. Calculate the standard deviation of Keq for all statistically significant trials n Calculate the COV of Keq for all statistically significant trials.

Answer 1

Well done with the equilibrium concentrations of Fe³⁺ {Fe(NO₃)₃} and SCN^-.

Notice that SCN^- is the limiting reactant, which will consume completely to give FeSCN²⁺.

Solution 5.

The equilibrium concentration of FeSCN²⁺ = 0.0002 M

Solution 6.

The equilibrium concentration of FeSCN²⁺ = 0.0006 M

Solution 7.

The equilibrium concentration of FeSCN²⁺ = 0.001 M