Equilibrium Expressions Nov 2017

The equilibrium reaction below was studied at 448oC: H2(g) + I2(g)  2HI(g) Colourless Purple Colourless The following observations were made: The purple colour never completely disappears The same intensity of purple is present at the end of the reaction regardless of whether the reaction starts with, for example, 1 mole each of H2 and I2 or it starts with 2 moles of HI.

The equilibrium reaction below was studied at 448oC: H2(g) + I2(g)  2HI(g) Colourless Purple Colourless The following relationship exists between the final concentrations of H2, I2, and HI regardless of starting concentrations: [HI]2 = 49.5 this value changes if T changes [H2][I2] 49.5 is called the equilibrium constant Keq and the relationship is called the equilibrium expression.

The equilibrium reaction below was studied at 448oC: H2(g) + I2(g)  2HI(g) Colourless Purple Colourless The equilibrium expression can easily be derived for any equilibrium reaction – the products go in the numerator, the reactants in the denominator and the coefficients become the exponents. 2A(aq) + 3B(aq)  C(aq) Keq =

Write the equilibrium expressions for the following equilibrium reactions: SO(g) + O2(g)  SO3(g) 2SO2(g) + O2(g)  2SO3(g) N2(g) + 3H2(g)  2NH3(g) C(s) + O2(g) CO2(g) 2Na(s) + Cl2(g)  2NaCl(s)