posted by Tyler .
I have a word problem that is driving me crazy, I don't even know where to begin. It goes like this: "A pesticide contains thallium (I) sulfate. By reacting 10.20 grams of the pesticide with excess sodium iodide, 0.1964 grams of thallium (I) iodide is produced by the following reaction: Tl2SO4 + 2 NaI ---> 2 TlI + Na2SO4. What is the mass percent of thallium (I) sulfate in the pesticide?" If someone could help me with it or just show me how to start it off, I'd be very grateful.