Chemical Reactions 2: Equilibrium & Oxidation-Reduction

Chemical Reactions 2: Equilibrium & Oxidation-Reduction

Factors Affecting Equilibrium Factors affecting the rate of the forward and reverse reactions, would have an impact on the resultant equilibrium. These factors are: _Concentration _Temperature _Pressure _Use of a catalyst

Factors Affecting Equilibrium Le Chatelier’s principle: “If the conditions of a system at equilibrium are changed, the equilibrium will shift in the direction necessary to restore the original condition” Changing c, T, P, or using a catalyst affects the equilibrium only temporarily as the system will seek to reach a new equilibrium

Factors Affecting Equilibrium

Factors Affecting Equilibrium Concentration A + B C + D _Increasing the concentration of one or all reactants shifts equilibrium toward products _Increasing the concentration of one or all products shifts equilibrium toward reactants

Factors Affecting Equilibrium Concentration A + B C + D A + B C + D *In the case of liquids and solids present at equilibrium, what changes is their masses not their concentrations

Factors Affecting Equilibrium Temperature A + B + 20kJ C + D A + B + 20kJ C + D _Increasing the temperature favours the endothermic reaction _Decreasingthe temperature favours the exothermic reaction

Factors Affecting Equilibrium Reverse Reverse Reverse

Factors Affecting Equilibrium Pressure A(s) + 2B(g) 3C(g) + D(l) • If P increases, equilibrium shifts • If P increases, equilibrium shifts _ONLY applicable to gas molecules _Increasing the pressure favours the reaction with lower number of gas molecules _Decreasingthe pressure favours the reaction with higher number of gas molecules 3 gas molecules 2 gas molecules

Factors Affecting Equilibrium Neither one is favoured Forward is favoured 2 2 4 Reverse is favoured Neither one is favoured Neither one is favoured 3 4 4 Reverse is favoured 2 4 3 Forward is favoured 3

Factors Affecting Equilibrium Catalyst A + B C + D _Catalysts DO NOT have any effect on the concentration of the substances at equilibrium. By lowering the activation energy, catalysts favor both the forward and the reverse reactions, regardless of whether they are exothermic or endothermic. _Catalysts made possible to achieve equilibrium FASTER

Factors Affecting Equilibrium Applications of equilibrium (Haber process) N2(g)+ H2(g) NH3(g)+heat _Exothermic reaction, not favored by high temperatures _Incrementing Pressure favors yield (less number of gas molecules), but increases production costs _Low yield since equilibrium favors reactants _Yield is increased by removing NH3 as it is produced, therefore shifting equilibrium towards products _Use of a catalyst to achieve equilibrium FASTER (at lower values of Temperature)

Factors Affecting Equilibrium Applications of equilibrium (Haber process) *Le Chatelier’s principle proves very useful since decreasing concentration of ammonia (by removing it as it is produced) displaces equilibrium to the forward reaction, thus INCREASING the yield

Factors Affecting Equilibrium Equilibrium in Nature (Water cycle) As a result of Global Warming, T increases, which displaces water equilibrium toward the melting of polar ice caps and the production of vapor water, another GHG.

Factors Affecting Equilibrium Equilibrium in Nature (Carbon cycle) Phytoplankton uses CO2 dissolved in ocean waters to produce oxygen (marine photosynthesis). Acid rain will increment the concentration of H+ ion and shift reactions 2 & 3 to the right, which will increase the concentration of H2CO3, thus shifting reaction 1 to the release of CO2 into air instead of dissolving it in water. This affects directly Phytoplankton, one of the basic components of ocean food chain, and oxygen production

Chemical Reactions 2: Equilibrium & Oxidation-Reduction