Equilibrium

• Open systems exchange matter and energy
• Closed systems exchange only energy
• Physical changes are usually reversible
• A chemical reaction can be reversible in a closed system
• Dynamic Equilibrium is when the rate of the forward reaction is equal to the reverse reaction
• Product favoured when reaction is forward
• Reactant favoured when reaction is reverse
• Rates are equal and concentration is constant when lines on a graph are flat and horizontal
• Forward position means product favoured thus high percentage yield of product
• High temperature provides more energy to overcome Ea
• Increasing temperature shifts reaction towards endothermic direction (absorb)
• Le Chateliers principle states if a system is subjected to change, it will partially adjust itself to oppose the effect of change
• Collision theory 3 factors; collide, have sufficient energy and correct orientation
• Increasing pressure shifts reaction to side with fewer molecules
• Increasing concentration will shift reaction to the opposite
• Diluting will shift reaction to side with most mols
• Catalysts do no affect position of equilibrium, only rate
• Inert gases do no affect equilibrium position as concentration is unchanged
• Only temperature changes Kc
• Kc is the ratio between product and reactants, only way to change ratio is temperature
• Large Kc means product/forward favoured
• Small Kc means reactant/reverse reaction favoured
• An acid donates H+ ion
• Bases accept H+ ions
• Strong acid and bases disassociate entirely
• Strong acids and bases have increased conductivity (mobile charges/ions)
• Kw = [H+][OH-]
• pH = -log[H+/OH-]
• [H+/OH-] = 10^-pH
• Amphiprotic acts as both and acid and base
• Buffers resist changes in pH
• catalyst lower the Ea, thus increased rate but done equally therefore no concentration change
• Q > Kc, product is favored therefore shift reverse
• Q = Kc, reaction at equilibrium
• Q < Kc, shift right to create more product thus increasing Q
• Metal + Acid = salt + H2
• Metal oxide + Acid = salt + H2O
• Acid + Carbonate = salt + H2O + CO2
• Acid + Base = salt + H2O
• amphoteric acts as both an acid or base