How pH Affects the Structure of an Organic Compound

Whether a given acid will lose a proton in an aqueous solution depends on both the pK of the acid and the pH of the solution. The relationship between the two is given by the Henderson-Hasselbalch equation. (Its derivation is on page 74.) 

This is an extremely useful equation because it teUs us whether a compound will exist in its acidic form (with its proton retained) or in its basic form (with its proton removed) at a particular pH. Knowing this will be important when we are assessing the reactivity of organic compounds. 

In other words, compounds exist primarily in their acidic forms in solutions that are more acidic than their pK values and primarily in their basic forms in solutions that 

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