If you have 3 moles of I2, how many moles of NaI will you make in this reaction? 2Na + I2 -> 2NaI

Question

If you have 3 moles of I2, how many moles of NaI will you make in this reaction?

2Na + I2 -> 2NaI

Answer 1

You should have learned how to use dimensional analysis. That, coupled with the stoichiometry of the balanced equation is all you need to answer this question.

3 mols I₂ x 2 mol NaI / mol I₂ = 6 mols NaI needed. (mols I₂ cancel, leaving you with mols NaI)

Answer 2

This is a mole ratio problem. By looking at the balanced equation that was given, we can figure out the mole ratio by looking at the coefficients. For example, for every 2 moles Na, 2 moles NaI are made. I know this because I looked at the coefficients in front of the two compounds. In the same way, for every one mole of Iodine, 2 moles NaI will be made. How do I know this? The coefficient in front of I2 is 1. Whenever there is no coefficient in front of the element or compound, you must assume that it is a 1. Therefore, to answer your question, for every 3 moles of I2 there will be 6 moles NaI.