Question

So basically, this excel sheet shows how to get the Equilibrium Constant of Fe⁺³ + SCN^- ⇆ FeSCN⁺² and I'm not sure what I need to change in to formulas to replicate this solution for Fe⁺³ + 2 SCN^- ⇆ Fe(SCN)₂⁺¹

Thanks.

Laboratory Data 0.4084 Slope of cal curve (from your pre-lab -- the mo [Fe(NO3)3] 0.002 [KSCN] 0.002 from the bottles in the lab. from the bottles in the lab. Data analysis part 1 For Fe3+ + SCN- <=> Fe(SCN)2+ Test tube number 2 Absorbance 0.088 0.19 0.245 0.385 0.499 initial mols Fe3+ = $B$5*0.05 = $B$5*0.05 =$B$5*0.05 =$B$5*0.05 =$B$5*0.05 initial mols SCN- = $B$6*0.01 =$B$6*0.02 =$B$6*0.03 =$B$6*0.04 =$B$6*0.05 [Fe(SCN)+2]eq =B11/$D$4 =B12/$D$4 =B13/$D$4 =B14/$D$4 =B15/$D$4 5 Test tube number 2 3 4 moles Fe(SCN)2+ eq =E11*0.01 =E12*0.01 =E13*0.01 =E14*0.01 =E15*0.01 moles of Fe+3 eq. =C11-B18 =C12-B19 =C13-B20 =C14-B21 =C15-B22 moles of SCN-eq. =D11-B18 =D12-B19 =D13-B20 =D14-B21 =D15-B22 Test tube number Kc [Fe3+] eq =C18/0.01 =C19/0.01 =C20/0.01 =C21/0.01 =C22/0.01 [SCN-Jeg D18/0.01 =D19/0.01 =D20/0.01 =D21/0.01 =D22/0.01 3 =E11/(B25*C25) =E12/(B26*C26) =E13/(B27*227) =E14/(B28*C28) =E15/(B29*C29)

Answer 1

Following is the - complete Answer -&- Explanation: for the given Question, in.....typed format...

$\Rightarrow$Answer:

As described below, under section:  "Explanation" ... in detail...

$\Rightarrow$Explanation:

Following is the complete Explanation, for the above Answer...

• Given:​​​​​​​

Following will be the given compounds, and we will have to consider the reaction between these compounds:

1.   Iron(III)nitrate : Fe(NO3)3 , which by ionic dissociation, in its aqueous solution will give the following ions, i.e. Fe3+ and NO3- , i.e. Fe(NO3)3 (aq) $\rightleftharpoons$ Fe3+ (aq) + SCN - (aq)
2. Potassium thiocyanate:   KSCN , which by ionic dissociation, in iys aqueous solution, will produce the following:   i.e.  KSCN (aq)  $\rightleftharpoons$ K+ (aq) + SCN - (aq)   
3. We have determined the following reaction: Fe3+ + SCN- $\rightleftharpoons$ Fe(SCN)2+, and we have determined the value of the equilibrium constant ( Keq ), of the above reaction.

• ​​​​​​​Step - 1:

​​​​​​​Now, if we consider the following balanced chemical equation:

$\Rightarrow$ i.e. Fe3+ (aq) + 2 SCN - (aq)  $\rightleftharpoons$ Fe(SCN)2+ (aq) -------------------------------- Eq. (1)

...then, we would be able to find the value of the equilibrium constant ( Keq ), of the reaction denoted by: Eq. (1)...

by following the following method...

• Step - 2:

​​​​​​​Following will be the expression, of the equilibrium constant ( Keq ), of the above reaction ( i.e. Eq. (1) ):

$\Rightarrow$   Keq =   ( [Fe(SCN)2] +eq ) / [ [Fe3+]eq  x [SCN -]2eq ) ---------------------- Equation - (2)

$\Rightarrow$ Where:

1. [Fe(SCN)2] +eq =   Molar concentration of Fe(SCN)2+ , at Equilibrium.
2. [Fe3+]eq = Molar concentration of Iron (III) or Fe3+ , cation, at Equilibrium.
3. [SCN -]eq = Molar concentration of thiocyanate anion, i.e. SCN - , at Equilibrium.

• ​​​​​​​Step - 3:

​​​​​​​Now, we can solve the rest of the problem, based on the following assumption of the initial concentrations...

Let's assume the following initial concentrations:

1. Initial molar conc. of Fe(SCN)2+ , will be: [Fe(SCN)2+] = 0.0 M ( mol/L )
2. Initial molar conc. of Fe3+ , will be: [Fe3+] = 1.0 M ( mol/L )
3. Initial molar conc. of SCN - , will be:  [SCN -] = 1.0 M ( mol/L )

• ​​​​​​​Step - 4:

​​​​​​​Therefore, we can build the following ICE Table, in order to determine the values of the Equilibrium concentrations, of the compounds, in order to determine the value of the Equilibrium constant ( Keq ), by following Equation - 2, as given above...

$\Rightarrow$ Following is the desired ICE Table: -----

	[Fe3+], M ( mol/L )	[SCN -], M ( mol/L )	[Fe(SCN)2+], M ( mol/L )
Initial ( conc. )	1.00	1.00	0.00
change	- X	- 2 X	+X
equilibrium ( conc.)	( 1.0 - X )	( 1.0 - 2X )	+X

• Step - 5:

​​​​​​​Therefore, following will be the expression, of the Equilibrium constant: ( Keq ) :

$\Rightarrow$Keq =   ( [Fe(SCN)2] +eq ) / [ [Fe3+]eq  x [SCN -]2eq )

$\Rightarrow$Keq =   ( +X ) / [ ( 1.0 - X )  x ( 1.0 - 2X )2 ] -------------------------- Equation - ( 3 )

Now, if we can determine the value of  'X'  , olugging in the value in the Equation - ( 3 ) , above, we will be able to determine the value of the Equilibrium constant ( Keq ), of the reaction.

$\Rightarrow$ Therefore, the above is the process of determination, of the value of the Equilibrium constant ( Keq ), of the reaction:. Fe3+ (aq) + 2 SCN - (aq)  $\rightleftharpoons$ Fe(SCN)2+ (aq) ------------ Thanks !!!

------------------------------------------------------------------------------------------------------------