How does acid affect the pH and H concentration when added to water?
An acid should reduce
When an acid is added to water it is conceived to increase concentrations of the characteristic cation (of water!):
This affects the equilibrium that already operates in water under standard condtions:
Note that if we take negative logs to the base 10, we get an expression that should be familiar:
OR, using the standard definition,
So, at neutrality, i.e.
For strong acids, e.g. hydrogen halides, perchloric acid, sulfuric acid, the first equilibrium lies strongly to the right. Whatever the strength of the acid,
And thus in an acidic solution,
I acknowledge that you have been hit with a lot of facts and definitions. Review your notes, and ask for clarification if there are queries.