I am trying to fill in the rest of the calculations. I believe that I can solve everything if I am able to figure out c.1 [FeNCS2+], equilibrium, from calibration curve (mol/l) (from graph I think)
C.2 moles FeNCS2+ at equilibrium (10 ml) (mol)
Any insight would help.
I provided instructions for the whole lab along with my equations and graph .
In Part B, precise volumes of knownCS rtnf concenrations of e" and SCN are and SCN and the eguilibriam moles egoal number Therefore, de moles of Fe, . a. equilit num (unreacted) is Similarly, the moles of SCN at equilibrium (unreacsed of FeNCs are easily calculated from k ogeann 34 A, for every mole of FeNCS', that exists at of males of Fe,·and SCN-have reacted so reach equartrum. mol FeNCS (34.6) (34.7) mol SCN (34.8) Mmol SCN-mol SCN Again, since the total volume of the reactiom mixture is kmown precisely, the lbrium concentrations of Fc and SCN (their equilibrium concentrations) and SCN (their equilibriu mcasured equilabrium molar concentration of FeNCS from the calihration curve, into itution of the three equilibrium molar concentrations the the mass action expression provides the value of the equilibrium constant, Ke Calculations for A are involved, but completion of the Prelaboratory Assignment steps. The Report Sheet is also outlined in such detail as to The calculations for K, should elarify nmost of the teps. The Report Shee is a assist with the calculations. Be lated data. aware of the number of significant figures when recording measured and calcu- ExPERIMENTAL PROCEDURE Procedure Overview: FeNCS is prepared for a calibration curve, a plot of absorbance versus concentralion. A second set of equilibrium prepa tive equilibrium molar concentrations of FeNCS. By carefully measuring the initial amounts of reactants placed in the reaction systems and the absorbance, the mass action expression at equilibrium can be solved; this equals K One set of solutions having known molar concentrations of is prepared and mixed to determine the respec- A large number of pipets and 100-mL volumetric flasks are used in this experi- ment. Ask your instructor about working with a partner. A spectrophotometer is an -expensive, delicate analytical instrument operate it with care, following the advice of your instructor, and it will give you good data. A Set of Standard tions to Establish a bration Curve The set of standard solutions is used to determine the absorbance of known molar con- centrations of FeNCS. A plot of the data, known as a calibration curve, is used to determine the equilibrium molar concentrations of FeNCS3 in Part B. Once the standard solutions are prepared, proceed smoothly and methodically through Part A.4. Therefore, read through all of Part A before proceeding. 1. Prepare a set of the standard solutions. Prepare the solutions in Table 34.1. Pipet 0, 1, 2, 3, 4 and 5 ml. of 0.001 M NaSCN into separate, labeled, and clean 25-mL volumetric flasks (or 200-mm test tubes). Pipet 10.0 mL of 0.2 M Fe(NO) into each flask (or test tube) and quantitatively dilute to 25 mL (the mark on the volumetric flask) with 0.1 M HNO,. Stir or agitate each solution thoroughly to ensure that equilibrium is established. An Equilibrium Constant
