mole calculations?

Question

if 2Li react to form H2, does that mean i hav to times or divide the number of moles of lithium by 2?
tnx

Answer 1

You are probably referring to the reaction:

2Li(s) + 2H2O → 2LiOH(aq) + H2(g)

You do not necessarily need to divide the number of moles of Li by 2. It will depend on what may be asked about the reaction details.

If you are asked how many moles of H2 are produced for each mol of Li, then you may want to write the reaction as:

Li(s) + H2O → LiOH(aq) + (1/2)H2(g)

Answer 2

Okay, well in this case you would need the chemical equation first, therefore:

2Li(s) + 2H20 ---> 2LiOH + H2(g)

If you are given the amount of Li in the reaction, and want to know how much of each product would produce then it's the matter of knowing your mol ratio. Since the mol ratio of Li : LiOH is 2:2 or 1:1, therefore, the mol value for LiOH does not change. But, in the case of Li : H, the mol ratio is 2:1, therefore, you have to divide by 2 to get your mol value for H2. The reason for diving is that for every 2 mol of Li you get 1 mol of H2, and for every 2 mol of Li you get 2 mol of LiOH. Therefore, you have to work out the mole ratio of each reactants and products to solve for the answer.

Hope that helps!

Good luck =]

Answer 3

no