N2+3H2=2NH3;
As we know
N2+H2=100 atm.
Let
Partial pressure of N2 &H2 be
= pN2 +p3H2
=P +3P
=4P
Therefore,
4P=100
P=25
As we know,20% mixture react means α=2. As per the Formula,
α=x÷P;
x=5
So, N2+3H2=2NH3
Intially, The pressures of N2, 3H2 and 2NH3 would be 25, (3×25) and (2×25) i.e., 25,75 and 50 atm respectively.
At Equilibrium, the pressures would be (25-x), (75-3x), 2x
i.e.,
(25-5) ,(75-15), {2(5)} = 20,60,10 atm resp.
P=20+60+10
P=90 atm
Hope this helps!!!

Calculating the Pressure Change in a Closed Vessel after Chemical Reaction

To understand why the pressure would be 90atm after 20% of the N2 and H2 mixture reacts, we need to first use the balanced chemical equation for the reaction:

N2 + 3H2 → 2NH3

1. Determine the initial moles of N2 and H2:

Assuming that we have 1 mole of the mixture, then the initial moles of N2 and H2 are:

N2 = 0.8 moles (20% of 1 mole)
H2 = 0.6 moles (3 times the moles of N2)

2. Determine the limiting reactant:

To determine the limiting reactant, we need to calculate the moles of NH3 that can be formed from each reactant. The reactant that produces the least amount of product is the limiting reactant.

From the balanced equation, we know that 1 mole of N2 reacts with 3 moles of H2 to produce 2 moles of NH3. Therefore, the moles of NH3 that can be formed from N2 and H2 are:

NH3 from N2 = 0.8/1 x 2/1 = 1.6 moles
NH3 from H2 = 0.6/3 x 2/1 = 0.4 moles

Since H2 produces the least amount of NH3, it is the limiting reactant.

3. Determine the moles of H2 that react:

Since H2 is the limiting reactant, all of the H2 will react. Therefore, 0.6 moles of H2 will react.

4. Determine the moles of NH3 formed:

From the balanced equation, we know that 3 moles of H2 react with 1 mole of N2 to produce 2 moles of NH3. Therefore, the moles of NH3 formed from the 0.6 moles of H2 that reacted are:

NH3 = 0.6/3 x 2/1 = 0.4 moles

5. Determine the moles of N2 left:

Since only 0.4 moles of NH3 were formed, there must be some N2 left over. The moles of N2 that did not react are:

N2 left = 0.8 – 0.4/1 x 1/3 = 0.6 moles

6. Determine the final pressure:

To determine the final pressure, we need to use the ideal gas law:

PV = nRT

Assuming that the temperature and volume stay constant, the equation becomes:

P1V1 = P2V2

The initial pressure was 100atm and the initial moles were 1 mole. The final pressure can be calculated as follows:

P2 = P1 x (n2/n1)

n1 = moles of the mixture = 1 mole
n2 = moles of N2 left = 0.6 moles

P2 = 100 x (0.6/1) = 60atm

However, we need to add the pressure of the NH3 that was formed. NH3 is also a gas and will contribute to the total pressure of the system. Assuming that the volume stays constant, we can use