This little website shows you the pH of various acids, bases, food products, bodily fluids, cleaners, and more!
Here's a random substance:
pH of Arsenic Acid
Chemical formula: H3AsO4
Also known as: arsoric acid
Arsenic Acid is Strongly Acidic
At concentration of 1 mM, it has a pH of 3.08
At concentration of 10 mM, it has a pH of 2.31
At concentration of 100 mM, it has a pH of 1.7