What is the chemical formula of sodium sulfate?
(1) Na2SO4 (2) Na2SO3
(3) NaSO4 (4) NaSO3
Answer and Explanation: Too write a chemical formula from a name, we must first determine whether the compound is ionic or covalent. Since sodium is a metal (on the left on periodic table), sodium sulfate must be an ionic compound. Next, we will write the symbols for the two ions with their corresponding charges (oxidation numbers). Sodium: Na +, sulfate SO4 2-. The formula for sulfate can be found on reference sheet in polyatomic ions section. Now, all that is left to do is to combine the ions by giving their oxidation numbers to their partners in the form of subscripts. Therefore, Na should get a 2, and SO4 should get a 1, making the formula Na2SO4, choice (1).