Consider the reaction below.

Upper C upper C l subscript 5 (g) double-headed arrow upper P upper C l subscript 3 (g) plus upper C l subscript 2 (g).

At 500 K, the reaction is at equilibrium with the following concentrations.

[PCI5]= 0.0095 M
[PCI3] = 0.020
[CI2] = 0.020 M

What is the equilibrium constant for the given reaction?

Kc = 0.042

Explanation:

PCl₅ → PCl₃ + Cl₂

The equilibrium constant's equation will be

Kc = [PCl₃] [Cl₂] / [PCl₅]

Kc = (0.02 x 0.02) / 0.0095

Kc = 0.0421

The equilibrium constant for the given reaction is 0.0421.

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !