• Froth floatation: crushing of the ore, then air bubbles are passed through a mixture of water and crushed ore. It can increase the concentration of the metal from less than 1% to 50%.

• after the ore is concentrated, a series of reactions produces the metal from the ore:

1. roasting uses oxygen gas to convert metal sulfides to metal oxides.

2. Then it goes through reduction, where it is heated extremely with carbon or carbon monoxide, reducing the metal ions in the oxide to the metal. It is a vapor that is then condensed.

Calculating enthalpy

• The enthalpy of a reaction is calculated from the enthalpies of formation, ΔH_f (the amount of energy it takes to form one mole of a substance from its elements at a stated temperature).

• Because energy is conserved in a chemical reaction, ΔH_reaction is the difference between the total ΔH_f of the reactants and the total ΔH_f of the products.

• a negative value for ΔH_reaction means the reaction is exothermic, same as ΔH_f

• ΔH°_reaction = total ΔH°_f(products) - total ΔH°_f(reactants)

Gibb’s Free Energy

• Spontaneity of a reaction depends on gibb’s free energy.

• ΔG° = ΔH° – TΔS°

• ΔG° < 0; = spontaneous

Any time a compound’s ΔH_f is equal to 0, it is because it is in in it’s standard state.