Question

How can some substances (water, for example) act in some reactions as an acid and in other reactions as a base?

I don't need the name. I just want to know why because google wasn't very helpful

Answer 1

Water can donate a hydrogen ion and form hydroxide `OH^-`, making it an acid. It can also receive a hydrogen ion and form hydronium `H_3O^+`, making it a base. Hope this helps.