Question

Calculate iron(III) thiocyanate complex ion concentration (in M) for each solution. Record in Lab Data A Lab Data -X OD Verify your concentration calculation Did you report your data to the correct number of significant figures? Stock solution 0.20000 yellow 0.00200 colorless Concentration iron(III) nitrate [Fe(NO3)3l (M) Color of iron(III) nitrate Concentration potassium thiocyanate [KSCN) (M) Color of potassium thiocyanate Volume iron(III) nitrate (mL) Volume potassium thiocyanate (mL) Volume Dl water (ml) Concentration iron(III) thiocyanate ion in stock solution [FeSCN21 (M) Color of stock solution 10.00 2.00 8.00 0.000200 red-orange Diluted solutions Solution 1 Solution 2 Solution 3 400 4.00 4.00 ELS 1.00 Volume stock solution (mL) Volume Dl water (mL) Concentration iron (III) thiocyanate ion [FeSCN2+1 (M) 2.00 3.00 0.0002 0.000200 0.000171 Calibration curve Solution Concentration iron(III) thiocyanate ion [FeSCN21 (M) Absorbance Stoc

Answer 1

The student's task involves complex ion concentration calculations in solution chemistry with application of equilibrium constant expressions, stoichiometry, and dilution formulas to determine concentrations of diluted solutions.

Step-by-step explanation:

The student's question involves calculating the concentration of iron(III) thiocyanate complex ion, [FeSCN]2+, in various solutions. The calculation of iron(III) thiocyanate concentration uses the initial concentrations of reactants, the volume of reactants used, and the dilution factor from further adding DI water or stock solutions. The understanding of the reaction equilibria, solubility, and complex ion formation principles, such as represented by the equilibrium constant expressions and stoichiometry of reactions, is key in performing these calculations.

For instance, when using a stock solution of known concentration to create diluted solutions, the concentration of the diluted solution (C2) can be found using the formula C1V1 = C2V2, where C1 and V1 are the concentration and volume of the stock solution, respectively, and V2 is the total volume of the diluted solution.

Answer 2

The iron(III) thiocyanate concentrations are determined using stoichiometry for the stock solution and dilution calculations for the diluted solutions, reported with the correct number of significant figures.

Step-by-step explanation:

To calculate the concentration of the iron(III) thiocyanate complex ion for both the stock solution and the diluted solutions, we apply the concept of dilution and stoichiometry based on the provided volumes and concentrations.

Stock Solution Calculation

Using the provided volumes and concentrations of the reactants, the concentration of iron(III) thiocyanate in the stock solution is already given as 0.000200 M. This is calculated by stoichiometrically combining equal molar amounts of
`$$\text{Fe(NO}_3\text{)}_3$$`and KSCN, given that the concentration of iron(III) thiocyanate complex ion is directly related to the limiting reagent, which in exact stoichiometric proportions is neither in this case.

Diluted Solutions Calculation

For diluted solutions, we apply the dilution formula C1V1 = C2V2, where C1 is the concentration of the stock solution, V1 is the volume of the stock solution, C2 is the concentration of the diluted solution, and V2 is the total volume of the diluted solution.

Solution 1: 0.000200 M (unchanged from the stock solution as no dilution occurred)

Solution 2: C2 = (0.000200 M × 2.00 mL) / (2.00 mL + 2.00 mL) = 0.000100 M

Solution 3: C2 = (0.000200 M × 2.00 mL) / (2.00 mL + 4.00 mL) = 0.000067 M