Stephany Matos

Chem Lab: Substance Equilibrium

Research laboratory 52

Synopsis

Iron (III) ions respond with thiocyanate ions (SCN-) to form straightener (III) thiocyanate, FeSCN2+. It is represented in the equation beneath:

Fe3+ (aq) + SCN- (aq) FeSCN2+ (aq)

Therefor the balance constant just for this reaction is usually:

KC sama dengan [FeSCN2+]/([Fe3+]вЂў[SCN-]

Just for this experiment i was able to identify the balance constant KC for this response. First we prepared five different mixtures with noted initial concentrations of iron (III) and thiocyanate ion. By using the colorimeter we decided the absorbance of each mix once it reached balance. Looking at the equation previously mentioned we see which the mole to mole bout between SCN- and FeSCN2+ is one particular: 1 so we can simply set up a ratio making use of the absorbancy to get the consentration of FeSCN2+: (where Absorbance one particular, Absorbance a couple of and [FeSCN2+ ] 2 are already known) Absorbance one particular = [FeSCN2+ ] one particular

Absorbance 2 = [FeSCN2+ ] two

We then simply pluged the determined value of [FeSCN2+ ] one particular to find the concentration of [Fe3+ ]#@@#@!!. [Fe3+ ] = [Fe3+ ](initial) - [FeSCN2+ ]

Though we prepared five several equilibrium alternatives, each having different concentrations, the balance constant KC for each of the reactions got similar values. By calculating the average and comparing each one of the values to the average there were a percent error of _____.

Post Lab Queries:

Write the KC expression for the reaction 1 . 1?

KC = [FeSCN2+]/([Fe3+]вЂў[SCN-]

Calculate the first concentration of [Fe3+ ] in combos 1-4 (total volume was 4mL)? [Fe3+]my spouse and i = 0. 002M (0. 002L) sama dengan 1 . 0e-3M

0. 004L

Calculate the first concentration of SCN- in mixtures 1-4 (total volume was 4mL)? M1V1=M2V2 -> 0. 2M(x) = zero. 002M(50mL) -> x = 0. 5mL (amount of SCN- (mL) added) [SCN- ]= 0. 002M (0. 0005L) = 2 . 5e-4 M

0. 004L

Compute [FeSCN2+] (control) in cuvette #5?

[FeSCN2+] = [SCN- ] since in the well balanced equation we come across that for every 1M of [SCN- ] used 1M of [FeSCN2+] is made so...