Question

Given 4Al +3O₂ = 2Al₂O₃ how do you determine the equilibrium oxygen pressure for a given temperature? How do you show how the reaction would respond with an increase or decrease in pressure?

Answer 1

4Al (s) +3O₂ (g) <------------------> 2 Al₂O3 (s)

               x                                                       ----------- initial

             x - 3y                                                         ------------ equilibrium

here Al and Al2O3 are solids. so they are not consider to take in equilibrium expression.so

Kp = P³_O2

Kp = (x - 3y)^3

if we know the initial pressure of O2 , and the value of equilibrium constant. then we calculate the equilibrium pressure of O2.

b)

if pressure decreases reaction shifts to more number of moles side.

if pressure decreases number of moles (volume) increases. so reaction shifts to back ward direction.

if pressure increases reaction shifts to less number of moles side.