Ease Into Prep with an MCAT^® Question of the Day

Sulfuric acid is composed of two positively charged hydrogen atoms and one sulfate ion. For a molecule of sulfuric acid to be neutral, the sulfate ion must have a -2 charge. (B) is correct.

Expert Approach:
What is the charge of the sulfate ion in sulfuric acid? I know from sheer exposure to chemistry problems that the sulfate ion has a charge of -2, which I match to (B). But I also could have reasoned my way there. I would have recognized that since sulfuric acid is a neutral molecule, the sum of the charges of all its atoms must equal zero. Its formula is in the question stem, and the two hydrogen atoms each have a charge of +1, so the sulfate ion must have a charge of -2. If I were really lost on this question, I still might have realized that the sulfate ion must have a negative charge to balance the positive charges of the hydrogen atoms, at the very least narrowing things down to (A) and (B).

Content Review:

Test Yourself: