A level chemistry

What indicator can be used when titrating a weak acid against a weak base? If any.

None. If you look at the titration curve for a weak acid-weak base titration, there isn’t really a vertical section as such, so it isn’t really possible to actually determine the endpoint of a weak acid-weak base titration with any indicator.

There are methods (such as “thermometric titrations”) to actually determine exactly when the endpoint of a weak acid-weak base titration is reached, but these aren’t assessed at A level and don’t involve pH indicators, so I wouldn’t worry about them.

Reply 2

Kallisto

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Original post by convivialkiwi

What indicator can be used when titrating a weak acid against a weak base? If any.

Technically speaking, yes you can use a weak base for a weak acid, but it has no meaning. The dissociation of the ions would be fairly small, that is to say there is no conjugation from an acid to a base and vice versa. That means in turn that the endpoint of an indicator for an acid or a base can't be determined. In short: it is senseless.