Titrations Technique Laboratory

Titration Background and Application

Quantitative analysis (determining the quantity/amount of a compound in a

sample) is important in every science, engineering, and health field. If you are in

the pharmaceutical industry, you need to determine how much of an active

ingredient is in the drug you are providing. If you are in the food industry, the

acid content in your preparations can be the difference between something being

properly preserved or tasting horrible. In environmental chemistry, determining

the concentrations of varies species that are dissolved in water is critical for

understanding risks to wildlife and appropriately treating wastewater.

A widespread technique for quantitatively determining the amount of a

compound in a sample is to use a titration. The basic ideas used in a titration are

to identify the compound we are trying to quantify (we call this compound the

analyte) and then slowly add a species that reacts with the analyte (we call this

species the titrant). When we are adding the titrant, it is critical to keep track of

how much we have added. We keep adding the titrant until all the analyte has

reacted with it, and then we make sure to stop adding titrant. We call the point

when we have added the exact amount of titrant to react with the analyte the

equivalence point of the titration.

Now we know exactly how much titrant has been added. By knowing the amount

of titrant we have added, we also know the amount of analyte in the sample by

using stoichiometry.

The moles of the titrant added are stoichiometrically equivalent to the

moles of the analyte.

If they have a 1:1 ratio in the balance equation, then the moles of titrant are

equal to moles of analyte. If they have a different ratio in the balanced equation,

then we just account for that different ratio by using the coefficients in the

balanced equation. Either way at the end point we have added the perfect

amount of titrant so that both the titrant and analyte completely react with

neither of them remaining.

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