Stronger acids have weaker conjugate bases. HCl is a stronger acid than water. Strong acids react with strong bases to form weaker acids and bases. NaOH is a stronger base than NH 3 . Water is a weaker acid than NH 4 Cl.
Weaker bases have stronger conjugate acids.
NH 3 is a weak base, but its conjugate acid, NH 4 Cl, is a strong acid.