[spas105]

Ok so i have a graph of pH vs log([HPO4^2-]/[H2PO4-])
Then it says to perform a least squares fit. I did that and then it asks to determine the pka from this graph. I dont understand how i do that from the graph.  I know how to use the equation but do not understand how to use the graph.

[Borek]

Linear regresion?

Take a look at the Henderson-Hasselbalch equation - it is exactly what you need.