back titration

[cootcoot]

i really just dont understand the whole concept.
can anyone explain it please?

[iamdan08]

Back titrations are used when one of the reactants in a titration are volatile substances (such as ammonia) or when a weak acid is being titrated with a weak base (or vice versa) and the end point is very hard to determine accurately by normal titration.

[beezy4eva]

and nearly every single back titration question you come across will be on lawn fertiliser

[doboman]

DUE TO NH3 BEING A WEAK ACID..:d

[Mao]

in some titrations, as the acid or base is really weak and the endpoint is not clear, it is far easier doing it the back way:

in the same way that you prepare the solution for straight titrations, this time you add in a known amount (and known concentration) of strong acid/base so all of the weak base/acid neutralised with some excess. This excess is then determined by titration. Since you know how many moles of the strong acid/base you have added, knowing the excess means you can calculate how much weak base/acid you have, except this time you have a clear end-point.

hope that helped

[bucket]

Back titrations are used when one of the reactants in a titration are volatile substances (such as ammonia) or when a weak acid is being titrated with a weak base (or vice versa) and the end point is very hard to determine accurately by normal titration.

the weak acid is not titrated with a weak base or vise versa, don't get confused =\.
read Mao's explanation... it was perfect, lol.

[Mao]

haha, weak acid + weak base = unclear endpoint²