Reversible reactions and equilibrium

Learning objectives

State that some reactions are reversible, as shown by the symbol ⇌, and describe how changing the conditions changes the direction of a reversible reaction, e.g. heating hydrated copper(II) sulfate or cobalt(II) chloride and adding water to the anhydrous compounds

State that a reversible reaction in a closed system is at equilibrium when the forward and reverse reactions occur at the same rate and the concentrations of reactants and products no longer change (Extended)

Predict and explain the effect of changing the temperature, pressure or concentration on the position of equilibrium, and state that a catalyst does not change the position of equilibrium (Extended)

State the equation for the Haber process, N₂ + 3H₂ ⇌ 2NH₃, the sources of the hydrogen (methane) and nitrogen (air), the typical conditions of 450 °C, 200 atm and an iron catalyst, and explain why these conditions are chosen in terms of rate and equilibrium yield (Extended)

State the equation for the key step of the Contact process, 2SO₂ + O₂ ⇌ 2SO₃, the sources of the sulfur dioxide (burning sulfur or roasting sulfide ores) and oxygen (air), the typical conditions of 450 °C, 2 atm and a vanadium(V) oxide catalyst, and explain why these conditions are chosen (Extended)