At what point is a base no longer added during a titration? when the ph increases suddenly in the flask when the phenolphthalein remains clear in the flask before the solution in the flask reaches the equivalency point before half of the base is completely drained from the burette

Option (a) is the correct answer.

Explanation:

The relation between pH and concentration of hydrogen ions is as follows.

              pH =

or,         pH =

At the equivalence point concentration of hydrogen ions equal hydroxide ions. Or, we can say concentration of hydrogen ions = 0.

Therefore,  pH =

                         =

                  pH  = infinity

Hence, there will be sudden increase in pH. Thus, we can conclude that when the pH increases suddenly in the flask then a base is no longer added during a titration.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.