quick chem question

[PredentVA]

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If 1 mole of N2 and 1 mole of H2 are
mixed and allowed to react according to
the equation N2 + 3H2 2NH3. What
is the maximum number of moles of NH3
that could be produced?
A. 2/3
B. 3/2
C. 2/1
D. 1/2
E. 1/1

How would one solve this?

 

[Cool Beans]

This is a limiting reagent problem. And we'll calculate the answer based upon the stoichiometry (mol to mol ratios given by the coefficients in the balanced rxn).
Based on the 1:2 ratio, 1 mol of N2 could produce 2 mol NH3 if it's the limiting reagent.
Based on the 3:2 ratio, 1 mol of H2 could produce 2/3 mole of NH3 if it's the limiting reagent. 1 mol H2*(2mol NH3/3mol H2)=2/3 mol NH3

Whichever reactant leads to less product is the limiting reagent and leads to the theoretical yield which is the maximum amount we could get and so we can only get a maximum of 2/3 mol NH3 with H2 being the limiting reagent.

 

[nlbaker7]

Find the limiting reagent, i.e. which reactant quantity will run out first (clearly H2 from our equation because for every 1 mole of N2 we have, we need 3 of H2 and we don't have that)

So we know the reaction will proceed as far as 1 mole of H2 will take us:

I'm big on using dimensional analysis to keep things clean:

1 mol H2 * (2 mol NH3 / 3 mol H2) = 2/3 mol NH3

This ^^^^^ just comes from the equation we are provided... the ratio of NH3 created to H2 used is 2/3

edit: BEATEN! and more concise too 😉 GJ cool beans

 

[ScratchMan]

This is a limiting reagent problem. And we'll calculate the answer based upon the stoichiometry (mol to mol ratios given by the coefficients in the balanced rxn).
Based on the 1:2 ratio, 1 mol of N2 could produce 2 mol NH3 if it's the limiting reagent.
Based on the 3:2 ratio, 1 mol of H2 could produce 2/3 mole of NH3 if it's the limiting reagent. 1 mol H2*(2mol NH3/3mol H2)=2/3 mol NH3

Whichever reactant leads to less product is the limiting reagent and leads to the theoretical yield which is the maximum amount we could get and so we can only get a maximum of 2/3 mol NH3 with H2 being the limiting reagent.

Great explanations.