sec3 pure chem qn

Blasst SG

A toilet cleaner contains the acid salt,sodium dihydrogen phosphate, Na2H2PO4. explain why sodium dihydrogen phosphate is both an 'acid' and a 'salt'.

Moka SG

Random guessing : Because it's a buffer? When it reacts with water, it will exist as both acid and alkaline.

UltimaOnline SG

Moka is right in that it could act as a buffer, but the most direct answer would be :

Na2H2PO4 is an acid because it (still) has the capacity to donate protons (ie. H+ ions).

Na2H2PO4 is also salt because it is a product between an acid (H3PO4) and a base (eg. Na2O, Na2CO3, NaOH, etc) in which one or more protons (ie. H+ ions) have been 'replaced' by the metal cation from the base.

SBS n SMRT SG

it is amphipthatic