Calculating Final Composition of Compounds in Haber's Process with 50% Yield

[Suyash Singh]

Homework Statement

30 litres of N2 and 30 litres of H2 are taken in Habers process with 50% yield.What is the final composition of the compunds in litres?

Homework Equations

N2+3H2->2NH3

The Attempt at a Solution

N2 + 3H2-> 2NH3
intial: 30 30 0
final: 30 - x/2 30-(3x)/2 (2x)/2

so,
30 - x/2 + 30-(3x)/2 = (2x)/2

this gives x=20
N2=20L
H2=0L
NH3=20L

Am i right?

 

[mfb]

so,
30 - x/2 + 30-(3x)/2 = (2x)/2

Why do you expect these two to be equal?

How is the yield defined? Using all hydrogen with just 50% yield is odd.

 

[Suyash Singh]

Why do you expect these two to be equal?

Howis the yield defined? Using all hydrogen with just 50% yield is odd.

litres are conserved
50 percent yield means half of theoretical value of NH3

 

[Borek]

litres are conserved

2 L of hydrogen plus 1 L of oxygen produce 2 L of gaseous water, 2+1 yields 2, what is conserved here?

50 percent yield means half of theoretical value of NH3

If only 50% of ammonia was produced, was all the limiting reagent consumed?

 

[Suyash Singh]

2 L of hydrogen plus 1 L of oxygen produce 2 L of gaseous water, 2+1 yields 2, what is conserved here?
If only 50% of ammonia was produced, was all the limiting reagent consumed?

Ok i understand the limiting concept now.

NH3 produced=2/3 x 30 =20 L

H2 left= 0 L

N2 left= 30- (1/2 x 20) =20 L

 

[Borek]

So which one is the limiting reagent here? And how much was left if only 50% reacted?

 

[Suyash Singh]

So which one is the limiting reagent here? And how much was left if only 50% reacted?

H2 the limiting reagent

all the elements react only 50 %?

 

[Borek]

H2 the limiting reagent

Right.

all the elements react only 50 %?

Stop guessing, use stoichiometry to calculate.

 

[mfb]

50 percent yield means half of theoretical value of NH3

But you got all of the maximum yield of NH3: You used up all hydrogen.
Based on that you can figure out how much NH3 is produced if you use only half of it.

 

[Suyash Singh]

NH3 produced = 50/100 x (2/3 x 30) = 10 L
H2 left = 30 - (3/2 x 10) = 15 L
N2 left = 30 - (1/2 x 10)= 25 L

 

[mfb]

That looks good.