The equilibrium constant, Kc is 3.2 x10 -34 at 25C for the reaction 2 HCl(g) <=> H2(g) + Cl2(g). what is The equilibrium expression, Kc for the reaction

Kc = (H2)(Cl2)/(HCl)^2

These are easy to write. Just remember this.
Put products on top, reactants on bottom, then make the exponent of each reactant and product the same as the coefficient in the balanced equation.

The equilibrium expression, Kc, for the reaction is obtained by writing the ratio of the product concentrations (H2 and Cl2) to the reactant concentration (HCl) raised to their stoichiometric coefficients.

For the given reaction:
2 HCl(g) <=> H2(g) + Cl2(g)

The equilibrium expression is written as:

Kc = [H2]^1 * [Cl2]^1 / [HCl]^2

where [H2] represents the concentration of H2 gas in mol/L,
[Cl2] represents the concentration of Cl2 gas in mol/L, and
[HCl] represents the concentration of HCl gas in mol/L.

Therefore, the equilibrium expression, Kc, for the given reaction is:

Kc = [H2] * [Cl2] / [HCl]^2

To determine the equilibrium expression (Kc) for the given reaction, we need to write the balanced chemical equation and then express the concentrations of the reactants and products.

The balanced chemical equation for the reaction 2 HCl(g) <=> H2(g) + Cl2(g) is as follows:

2 HCl(g) <=> H2(g) + Cl2(g)

Now, let's express the concentrations of the reactants and products in terms of variable "x":

[HCl] = Starting concentration - 2x
[H2] = Starting concentration + x
[Cl2] = Starting concentration + x

It is important to note that the change in concentration for H2 and Cl2 is +x since they are being formed, whereas the change in concentration for HCl is -2x since it is being consumed.

Now, let's substitute the concentrations into the expression for Kc:

Kc = ([H2] * [Cl2]) / ([HCl]^2)

Kc = ((Starting concentration + x) * (Starting concentration + x)) / ((Starting concentration - 2x)^2)

Given that Kc is 3.2 x 10^(-34) at 25°C, you can plug in the values and solve the equation to find the starting concentration and value of "x".

6.71 X 10^-18