Question

Can someone please help me with this ? I have tried to solve it but I feel like answer is wrong. When heated, lithium reacts with nitrogen to form lithium nitride:

6Li(s) + N2(g) --> 2Li3N(s)

What is the theoretical yield of Li3N in grams when 12.3 g of Li are heated with 33.6 g of N2?

Answer 1

i will give you the steps - because the steps are important and can be used through most
problems.

Step 1 get a balanced equation --you already have one

Step 2 we need to figure out the limiting reagent. we do this by obtaining the moles
of the reactants.

get the molecular weights of
MW of Li = ??g/mol(molecular wt from periodic table)
N2=??g/mol
Li3N=??g/mol

Step 3
then mult. supplied g by MW

(12.3g)(MW of Li) = moles

Step 4
you will see that Li is the limiting reagent
1 mole N2 need 6 moles Li

6Li --> 2Li3N

Li --> 1/3Li3N
one mole Li produces 1/3 mole Li3N so

Step 5
the moles from step 3 and multiply by the 1/3. this will give you the moles of Li3N produced


Step 6
take the moles of Li3N produced and multiply
by the Molecular weight of Li3N that is your

theoretical yield


go ahead and go thru the steps
see what you get