Rote Method for Simple Systems

Write all species of relevance or interest. Count the number of unknown species. You will need this many equations. 

If there are charged species, write a charge balance equation. 

You should now have the same number of equations as unknown species. Reduce these by algebraic substitution to one (or two) equations that can be solved for the unknown concentrations. At first, assume all activity coefficients are 1.0. 

If activity coefficient corrections are required, use the concentrations calculated in step 5 to estimate activity coefficients. Repeat step 5 using these new activity coefficients. Iterate on steps 5 and 6 until successive concentrations and activities stop changing within some acceptable limit. 

We will work through our example in detail, remembering that exactly the same procedure applies to more complicated problems. The problem is to calculate all concentrations (or activities) in an m-molal acetic acid solution. Follow the above steps in sequence  

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