Titration is the process of gradually adding a solution of known concentration to another of unknown concentration. In the presence of an indicator, which by changing color shows the progress of the reaction between the two, the concentration of the unknown can be found. The known solution is added gradually until a point is reached where an indicator swings wildly from one color to another. This is the equivalence point.
Example:
Manganese (VII) oxidizes iron (II) in acidic solution. The reaction begins with 12.0 of an solution of unknown molarity. Then 1.71M is released from a buret. The equivalence point is reached when 14.3 mL of the solution has been released. What is the concentration of the solution?
The first step is to write out the half reactions showing which species are oxidized and reduced. To balance the reactions in an acidic solution, use and . In a basic solution, use and .
