Equilibria & redox reactions

• What affects the value of Kc?

  Changing temperature. If change means more product formed, Kc rises.
• Dynamic equilibrium

  Rates of both reactions are same and concentration of reactants & products are constant. Only happens in closed system at constant temperature.
• Le Chatelier's principle:

  If a reaction at equilibrium is subjected to a change in concentration, pressure or temperature, the position of equilibrium will move to counteract the change.
• What happens when pressure is increased?

  Equilibrium shifts to side with fewer gas molecules to reduce pressure.
• What happens when conc. increased?

  Equilibrium shifts to opposite side to reduce conc.
• What happens when temperature is increased?

  Equilibrium shifts to endothermic side to absorb more heat.
• What happens when temperature is decreased?

  Equilibrium shifts to exothermic side to replace heat by producing more.
• What is a redox reaction?

  Oxidation & reduction happens simultaneously.
• What is an oxidation state of an element?

  Tells you total number of electrons it has donated or accepted.
• What is the oxidation state for uncombined elements or identical elements bonded together?

  Zero.
• What is the oxidation state of a simple monatomic ion?


  Same as its charge.
• What is the oxidation state of compounds or compound ions?

  Charge. Within compound ion, most electronegative element has negative oxidation state. Sum of oxidation states = overall oxidation state= overall charge on ion.
• What is the oxidation state for a neutral compound?

  Zero.
• What is the oxidation state for combined oxygen?

  -2, except in peroxides where its -1.
• What is the oxidation state for combined hydrogen?

  +1, except in metal hydrides (-1) & H2 (0).