2.9c: interpret the results of simple experiments to demonstrate the effect of a change of temperature, pressure and concentration on a system at equilibrium, eg (i) iodine(I) chloride reacting with chlorine to form iodine(III) chloride, or (ii) N2O4 > NO2

MANUFACTURING METHANOL

CO(g) + 2H2(g) → CH3OH(g)

AH = -91kJmol-1

Carried out with aluminium oxide pellets, coated in copper and zinc oxides, as a catalyst

Runs at 100atm and 575K

• there are three moles of gaseous reactants, and only one mole of product, so higher pressure = higher yield
• the reaction is exothermic, so higher temperature = higher yield, but if the temperature is not high enough, the reaction is too slow

CHANGING CONCENTRATION

ICl(l) + Cl2(g) ←> ICl3(s)

• increasing the concentration of chlorine gas will increase the yield of iodine trichloride
• decreasing the concentration of chlorine will cause the backward reaction to be favoured, decreasing the yield of iodine trichloride

CHANGING PRESSURE

2NO2(g) ←> N2O4(g)

• increasing the pressure = more yellow gas
• decreasing the pressure = more brown gas