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Any chemical reaction goes both ways

According to Le Chatelier, if at equilibrium point we make any change in concentration, pressure or temperature the point of equilibrium will move to counteract the change.

If the reaction produces heat then heating the system will move the equilibrium to the left and cooling the system will move the equilibrium to the right. If volume of the products is greater than the volume of the reactants then increasing the pressure will move the equilibrium to the left. Decreasing the pressure will move the equilibrium to the right. Increasing concentration of reactants will move the equilibrium to the right, increasing concentration of the products will move the equilibrium to the left.

Equilibrium constant K c = [C] * [D] / [A] * [B]

where [] is concentration in moles

H2 + I2 <=> 2HI

The concentration of products and reactants is raised to the power of their respective coefficients.

K c = [HI] ^2 / [H2] [I2]

The concentration of products and reactants is raised to the power of their respective coefficients: a, b, c, d.

Let us calculate the equilibrium constant for the following reaction.

2Al +6HCl + H20= 2AlCl3 +3H2

The concentration of HCl is 0,5 M, the concentration of AlCl3 is 0.2M and the concentration of H2 is 0.2M at equilibrium point.