How many Liters of N2 form when 1kg N2H4 reacts with 1.2kg O2

Answer 1

Hi Skylre,

First we have to write a balanced reaction equation:

N₂H₄ + O₂ -> N₂ + 2 H₂O

Next we have to determine our limiting reactant. Our limiting reactant is going to be the substance that is 100% consumed by the time our reaction has completed. Before doing any further calculations, it is easiest to convert the masses of each reactant into molar quantities first.

1,000 g N₂H₄ (1 mole / 32.05 grams) = 31.2 moles of hydrazine are available

1,200 g O₂ (1 mole / 31.98 grams) = 37.5 moles of O₂ are available

Now to determine our limiting reactant, we must determine how many moles of one reactant are needed to completely consume the other reactant:

Let's assume all of our hydrazine is consumed (using the coefficients from the balanced equation):

31.2 moles hydrazine (1 mole O₂ / 1 mole hydrazine)

= 31.2 moles of O₂ required to completely consume all of our hydrazine

Now let's assume all of our oxygen is consumed:

37.5 moles of O₂ (1 mole hydrazine / 1 mole O₂)

= 37.5 moles of hydrazine required to completely consume all of our oxygen

Now look back to the molar quantities of each reactant that we have available for this reaction. If all of our hydrazine was used up, we would need 31.2 moles of oxygen to consume all of it (and we have 37.5 moles of oxygen available). If all of our oxygen was used up, we would need 37.5 moles of hydrazine to consume all of it (which is not possible because we only have 31.2 moles of hydrazine available). Since we have enough oxygen to consume all of our hydrazine, but not enough hydrazine to consume all of our oxygen, we know that hydrazine is our limiting reactant and we will have an excess of oxygen at the end of the reaction.

So using the moles of hydrazine, we can calculate the moles of N₂ formed, and then the volume:

(remember that 1 mole of gas will occupy approximately 22.4 liters at STP).

31.2 moles hydrazine (1 mole N₂ / 1 mole hydrazine) ( 22.4 liters / 1 mole of N₂)

= 698.88 L of N₂ should be produced from this reaction