Question

Consider this reversible reaction: PCl5(g) + heat ↔ PCl3(g) + Cl2(g) Which change to the system will cause equilibrium to shift right and produce more PCl3? A) removing the heat B) adding Cl2 C) increasing the pressure D) removing the PCl3 as it forms

Answer 1

Explanation for each.
A) if heat is removed.. the reaction would want to produce more heat and hence reaction will shift backward causing a decrease in PCl3.
B)if Cl2 is added..the reaction will shift in such a direction such to decrease the amount of Cl2..so backward ..again PCl3 will decrease.
C)Reactant :product is 1:2.. wrong as increase pressure imply decrease volume...

D) is correct as if the Pcl3 is removed .. more PCl3 will be produced

Answer 2

D) is correct as if the
`PCl_(3) _((g))` is removed the equilibrium will shift to produce more
`PCl_(3) _((g))`

`PCl_(5) _((g))+heat`⇆
`PCl_(3) _((g)) +Cl_(2) _((g))`

The equilibrium will shift to "anulate" the disturbance. If we want to increase the production of
`PCl_(3) _((g))` we should give the system more heat of more
`PCl_(5) _((g))`, so they will be consumed to restore the equilibrium. Alternativaly we could decrease pressure, so the equilibrium shifts into producing
`PCl_(3) _((g)) +Cl_(2) _((g))` in order to restore the pressure equilibrium or we could withdraw
`PCl_(3) _((g))` as it is formed, so the equilibrium is shifted into formation of products.