What will be present?

Question

A 15-g sample of lithium is reacted with 15 g of fluorine to form lithium fluoride: 2Li + F2 --> 2LiF. After the reaction is complete, what will be present?

a.2.16 moles lithium fluoride only
b.0.789 moles lithium fluoride only
c.2.16 moles lithium fluoride and 0.395 moles fluorine
d.0.789 moles lithium fluoride and 1.37 moles lithium
e.none of these

Answer 1

This is a stoichiometry problem. Here is the concept. You do the math.

Convert the grams of Li and F to moles. Multiply each respectively by the molar ration. i.e. 2 moles of Li produces 2 moles of LiF(1:1) and 1 mole of F2 produces 2 moles of LiF (1:2).

This will give you the potential moles of LiF for each reactant. Take the smaller answer, as it is the limiting reactant, and convert to grams based on the molar mass of LiF. You then have all of the data you need to complete the problem

Answer 2

15g of Li and 15g of F2 gives you 30g of LiF.
i cannot work this out without the moles of Li or F2.
i would say none of these because i was always taught to work out the moles by the numbers so it would be 2LiF.
but here is a website that i looked at may help...
http://www.chemistrycoach.com/stoichiometry_2.htm