# Chemistry - Limiting reagents

1. Oct 18, 2006

### Joules23

Problem

My work

In part (b) do i just subtract the 3310 from 29700?

and part (c) im really lost.. i got 1 mol of NH_3 = 30.036g.. would i then multiply this by the limiting reagent mol(1059.957)??

Last edited: Oct 18, 2006
2. Oct 18, 2006

### leaf345

I dont think Nitrogen is the limiting reactant. The one that will produce the least amount of products is the limiting reactant. Figure out which one that is.

For part b, the difference between the moles of limiting reactant and excess reactant will give you how much reactant moles are left over.

3. Oct 18, 2006

### Mattara

Don't forget that there are 3 moles of $$H_2$$ for every one mole of $$N_2$$ in the equation.

$$n = \frac{m}{M}$$

4. Oct 18, 2006

### physics girl phd

watch out -- the prior responses are good hints towards a)... but for b) you need to figure out the amount of the other reactant that the limiting reactant will use up. the difference between the amount used up and the total amount is the excess.... just like what "excess" sounds like.

this is also a good check for a)... if you find that you need more of the other reactant than was given... there is something wrong somewhere.

5. Oct 23, 2006

### Joules23

OK now im understanding!... since i need 3$$H_2$$'s for every $$N_2$$, then, i can only use a total of 547.29g of $$N_2$$ out of the total 1059.96g i have, thus making the $$H_2$$ the limiting reagent since i will be using it all.

for part b) after subtracting 547.29 from 1059.96 i get 512.67, which is the excess of $$N_2$$

for part c) the reaction cannot go into completion, because all of the reactants are NOT used up.. hence the answer to part b... But since its asking IF, would i simply add 29700g of $$N_2$$ + 3310g of $$H_2$$, to get the answer: 33010g of $$NH_3$$??

Does this look good now?

EDIT: i forgot to add, my teacher is also asking, is Nitrogen oxidized or reduced? .. i say Oxidized, because each N is giving up 3 electrons, making it +3... each H is gaining one electron making it -1.. this makes both of them add up to 6.. am i right on this?

Last edited: Oct 23, 2006