M CHEM 2 LAB RE Chegg Study C NAL EXAT swebdavpid511048d

M CHEM 2 LAB RE × Chegg Study | C × NAL EXAT × swebdav/pid-511048-dt-content-rid-3916397_1/courses/11 M1106Fall201 THE DETERMINATION OF AN EQUILIBRIUM CONSTANT Given the following equilibrium concentrations for the reaction at 23 oC in this experiment: [Fe\') [SCN] [FeSCN+] 9.84 x 104 M 1.84 x 10\" M 0.156 x 104 M a) Write the balanced net equation of the reaction. b) Write the equilibrium expression or equation of the reaction. c) Describe the evidence of chemical reaction. d) Why is Beer\'s law used in determining the concentration of the product formed in the reaction? e) Calculate the equilibrium constant, Keg, of the reaction. 1) Is the reaction product favored or reactant favored? Briefly explain your answer.

Solution

From the given data

a) balanced net reaction,

Fe3+ + SCN- <===> FeSCN^2+

b) Equilbrium expression

Keq = [FeSCN^2+]/[Fe3+][SCN-]

c) The product formed here is a complex which is dark red in color. Thus formation of red coloration in solution proves chemical reaction has occured.

d) Beer\'s law is used for this reaction. So the concentration of the complex formed is directly proportional to the absorbance of the solution.

This is by relation,

Absorbance = molar absorptivity of complex x path length x concentration of complex

So by having absorbance value, one can easily calculate the concentration of complex ion product formed in the reaction.

e) Equilibrium constant,

Keq = (0.156 x 10^-4)/(9.84 x 10^-4)(1.84 x 10^-4) = 86.16

f) Since Keq is greater than >1, the reaction is product favoured. Numerator is bigger than the denominator.