Question

1.) If you were designing a titration based on a reaction that no one had ever used before in a titration, what “homework” would you need to do?

2.). Sometimes it is advantageous to perform what is called a “back titration”. Two steps are used:

            Step 1:             Add an excess of reagent R to react with analyte completely

            Step 2:             Titrate the excess reagent R with an appropriate titrant

This obviously takes extra work. Under what circumstances might this approach be preferred over a direct titration? What additional information would you need to know in order to achieve accurate analyte measurement?

Answer 1

Titration is used to estimate the concentration of the known volume of a solution by adding small drops (known volume) of another solution(titrant) whose concentration is known until the reaction reaches neutralization which can be observed as the color change. So if I were designing a titration based on a reaction that no one had ever used before in a titration, I would first find the acidity(pH) of the reactants and guess what should be the pH of the solution when reaction going on. Then I would titrate it with the corresponding titrant of known concentration with the corresponding indicator.

2.) Back titration is useful in many cases like when we want to know the kinetics of the reaction so that we have to calculate the concentration of the components involved in the reaction in short intervals of time. For that, if we collect the solution in the test tube and leave it for some time then the reactants involved in the reaction gets completely reacted we will not get the correct concentration of reagent at that time so in this case what we do is add analyte to excess reagent so that one of the reactant in the solution gets completely react with the analyte and the other reactants remains unreacted so that we can titrate that excess reagent to get the concentration value.

Additional information needed is the %error associates with each quantity we measured so that we can know the accuracy of the result we get.