20.5k views
3 votes
The exothermic reaction between liquid hydrazine

(
N
2
H
4
)
(N
2

H
4

) and liquid hydrogen peroxide
(
H
2
O
2
)
(H
2

O
2

) is used to fuel rockets. The products of this reaction are nitrogen gas and water. a. Write the balanced chemical equation. b. How much hydrazine, in grams, is needed to produce 10.0 mol of nitrogen gas?

User Reggoodwin
by
8.2k points

1 Answer

3 votes

Answer:

320.04 grams of hydrazine.

Step-by-step explanation:

Please check the format when posting a question. As best I can tell, we are being asked to balance the following reaction:

N2H4 + H2O2 = N2 + H2O

[hydrazine + hydrogen peroxide = nitrogen + water]

a) Start with the most complec molecule, N2H4, and pencil in a "1" for the coefficient:

1N2H4 + H2O2 = N2 + H2O

b) Now find homes for the 2 N and 4 H atoms:

1N2H4 + H2O2 = 1N2 + 2H2O [both the 2N and 4H atoms are now accounted for in the 1N2 and 2H2O molecules]

c) The oxygen needed for the H2O must come from the H2O2 molecule. We need 2 O atoms for the products [2H2O]. Add a coefficient of 1 to the H2O2 to supply the two O atoms:

1N2H4 + 1H2O2 = 1N2 + 2H2O

The O atoms are now balanced, but the H2O2 now adds 2 more H atoms. The only possible place for them to come from is the H2O2, so lets change its coefficient to 2:

1N2H4 + 2H2O2 = 1N2 + 2H2O

d) The N atoms are accounted for. But the others:

Reactant Product

N 2 2

H 8 4

O 4 2

We're missing homes for 4 H and 2 O atoms in the products. That is the equivalent of 2 H2O molecules, so add 2 to the existing coefficient of 2:

1N2H4 + 2H2O2 = 1N2 + 4H2O

Now we have:

Reactant Product

N 2 2

H 8 8

O 4 5

The equation is balanced.

-------------------

Now we are asked how much hydrazine is needed to produce 10.0 moles of nitrogen gas.

The balanced equation tells us that we'll get 1 mole of N2 for every 1 mole of N2H4. That's a molar ratio of 1:1 (1 moles N2)/(1 mole N2H4)

That means we need 10 moles of hydrazine to produce 10 moles of N2.

Convert 10 moles hydrazine into grams:

Find the molar mass of hydrazine: 32.04 grams/mole

Multiply by 10 moles:

(10 moles hydrazine)*(32.04 grams/mole hydrazine) = 320.04 grams of hydrazine.