Sooo difficult! problem about gas?

Question

Reaction of hydrogen at a partial pressure of 0.588 atm and oxygen at a partial pressure of 0.302 atm in a 5.00 L reaction vessel produced gaseous water.. Which gaseous element is the limiting reactant in the reaction?


It's super difficult for me. I hope you guys can help me out.

10 pts for the best answer. =)

thanks!

Answer 1

The balanced equation is
2 H2 + O2 >> 2 H2O
The ratio between H2 and O2 is 2 : 1

We can use the equation
p (H2) / pt = V( H2) / Vt
pt = 0.588 + 0.302 = 0.890 atm
0.588 / 0.890 = V (H2) / 5.00
V ( H2) = 3.30 L

p (O2) / pt = V (O2) / Vt
0.302 / 0.890 = V(O2) / 5.00
V (O2) = 1.70 L

p( H2) x V (H2) = n(H2) RT
p(O2) x V (O2) = n (O2 RT

p(H2) x V(H2) / p(O2) x V(O2) = n (H2) / n (O2)

0.588 x 3.30 / 0.302 x 1.70 = 3.78 = n (H2) /n (O2)
H2 is the limiting reactant

Answer 2

0.302 atm of O2 would require 0.604 atm of hydrogen. But there isn't that much, so hydrogen is the limiting reagent!

2H2 + O2 ----> 2H2O

This, then, is a simple problem using Dalton's Law of Partial Pressures. The size of the container is irrelevant. The partial pressure of each gas is proportional to its number of moles. We do not have enough information to work out the moles, and so we work in partial pressures.