In your handout you will note that Equation 18 closely resembles the equation for a line: 

y = mx + b 

Then one can plot y vs. x and determine the slope, where:

y  =        A          x  =  A ([Fe*] + [SCN*])
       [Fe*] [SCN*]    [Fe*] [SCN*]

The slope of the resulting straight line is Keq. 

m = Keq
In TodayÕs Experiment