Hello, I was able to get pretty far in my homework, but I need help figuring out this last question.

Question: The pKa for any weak acid can be determined from the Henderson Hasselbalch Equation pH = pKa + log [A- ] [HA]. Notice that this equation is like that for a straight line; y = mx + b. Using data from our table, we can take advantage of this fact to find an estimate for the pKa of p-nitrophenol.

For example, if we make the following substitutions: y = pH m = slope of the line = 1.0 (each increase in pH represents a directly proportional increase in log [A- ]/[HA] x = log [A- ]/[HA] b = pKa Then we can estimate the pKa for p-nitrophenol from a graph of pH versus log [A- ]/[HA] Prepare a second graph (Figure 2) of pH (y-axis) versus log [A- ]/[HA] (x-axis) using the values from Table 1. Use the scatter plot option in Microsoft Excel or similar and produce a line of best fit (regression) through the data points.

pH	Absorbance	[A-] (mM)	[HA] (mM)	log [A-]/[HA]
9.0	0.516	0.00004mM	0mM	N/A
8.0	0.409	4.09 X 10^-4mM	1.82 X 10^-4	1.63
7.5	0.308	3.08 X 10^-4	1.71 X 10^-4	-0.52
7.0	0.256	2.56 X 10^-4	7.11 X 10^-5	-0.6
6.5	0.108	1.08 X 10^-4	1.57 X 10^-5	-1.3
6.0	0.007	7.0 X 10^-7	1.9 X 10^-8	-3.5