Stoichiometry of Titration Reactions

At the equivalence point of a titration, exact stoichiometric amounts of the reactants have reacted, i.e., the amount of titrant added is the exact amount required to consume the amount of substance titrated in the reaction flask. If the reaction is one-to-one in terms of moles (moles of titrant equals the moles of substance titrated, as is the case for the reaction represented by Equation (4.4), for example), then the moles of titrant added equals the moles of substance titrated consumed  

This equation will be useful as we explore titration calculations in Sections 4.6 and 4.7. 

Some analysts prefer to work with equivalents rather than moles. In that case, the normality method of expressing concentration is used and the equivalent weight is needed, rather than the formula weight. The equivalent weight of one substance reacts with the equivalent weight of the other substance. In other words, the reaction is always one-to-one one equivalent of one substance always reacts with one equivalent of the other. Thus, we can write the following as a true statement at the equivalence point of the titration  

Standardization was defined in Section 4.2 as a titration experiment in which the concentration of a solution becomes known to a high degree of precision and accuracy. In a standardization experiment, the solution being standardized is compared to a known standard. This known standard can be either a solution that is already a standard solution or an accurately weighed solid material. In either case, the solute of the solution to be standardized reacts with the known standard in the titration vessel. If the solution to be standardized is the titrant, then the known standard is the substance titrated, and vice versa. We will now describe these two methods and the calculations involved. 

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But the stoichiometry of titration reaction A tells us that at the equivalence point [Fe ] = 5[Mn ] and [Fe ] = 5[Mn04]. Substituting these values into Equation D gives... 

As we learned in the discussion of the stoichiometry of titration reactions (Section 5-7), the equivalence point of a neutralization reaction is the point at which both acid and base have been consumed and neither is in excess. 

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