Two Monoprotic Acid-Base Systems

A consistent mathematical approach to all the problems in this section will greatly simplify these seemingly complex cases. Charge and/or material balancing equations will be the key, leading either to useful equations which are easy to solve exactly, or in some cases to reasonable numerical approximations. The general process is as follows  

Obtain an equation of linear terms involving the equilibrium species. Proton balance is usually the best approach, but charge and/or material balancing may be required in complex cases. 

Use the equilibrium constant expressions to eliminate in step 1 the minor (low concentration) species, retaining H and the major species for which we often have good numerical approximations, the analytical concentrations. 

Solve and check for internal consistency by getting numerical values for all species and checking the material balances. 

Example 1. Find H in 0.10 M NH4HCOO solution, ammonium formate. This involves both conjugates of the formic acid and ammonia systems. We perform a proton balance as follows. Write down the hypothetical species added together  

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