Final answer:
The pH of a coffee solution with a hydrogen ion concentration of 1.00 x 10^-3M is 3, making it acidic.
Step-by-step explanation:
The question asks to calculate the pH of a coffee solution with a hydrogen ion concentration of 1.00 x 10-3M. Using the pH formula pH = -log[H+], we find that the pH equals -(-3), which simplifies to pH = 3.
Therefore, the coffee has a hydrogen ion concentration that makes it an acidic solution, as any pH below 7 is considered acidic.