7.1 dynamic equilibrium
When doing stoichiometry calculations, we assume that reactions proceed until 1 of reactants run out
◦Some reactions do not proceed to completion
Chemical equilibrium : state of reaction where all reactants and products have reached constant concentrations in a closed system
◦Can tell by - color intensity, concentration, pressure
Dynamic equilibrium: balance between forward and reverse processes that are occurring simultaneously at the same rate
◦Forward reaction is favourable
◦Dynamic means moving
◦Solubility equilibrium: dissolve to form aqueous solution until point of saturation
‣ After saturation, any solid added appears to remain as solid, but rate of dissolution equals rate of recrystallization
• If both rates are equal, no observable charges occur
Equilibrium position: relative concentration of reactants and products in a system in dynamic equilibrium
Equilibrium → forward reaction is making products at same rate of the backward reaction
Phase equilibrium: same element different state (g to 1)
◦Some liquids gain enough energy from collisions to leave surface of liquid and movie into gas phase
◦When rate of 2 processes are equal, no further changes will be observed
Chemical reaction
◦Reaction favors reactants
‣ Percent reaction is much less than 1%
‣ Mixing reactants have no observable result
◦Reaction favors products
‣ Percent reaction is more than 99%
‣ Effect of reverse is negligible
◦Reaction that achieves noticeable equilibrium
‣ Between 1% 99%
• Percent less than 50 → reactants favoured but still equilibrium
• Percent more than 50 → products favoured but still equilibrium
ICE table