Equilibrium Unit Flashcards
What is dynamic equilibrium
a state of balance between two opposite processes taking place at the same rate
what is physical equilibria
phase equilibrium, solution equilibrium, and vapor liquid equilibrium
what is phase equilibrium
can exists between the solid and liquid phase of a substance, occurs at melting point of a solid . melting and freezing can occur at the same time. during equilibrium the relative amounts of ice and liquid water are constant
what is solution equilibrium
solids in liquids can exist in equilibrium only in a saturated solution. it reaches equilibrium when the rate of dissolving and recrystalization are equal and the solution is saturated.
what is vapor liquid equilibrium
the rate of evaporation will equal the rate of condensation. the number of particles becomes constant and also the vapor pressure.
what is chemical equilibrium
occurs only in reversible reactions. the forward and reverse reaction must occur at the same time. has to be in a closed system
what are the concentrations of the products/reactions generally like
at equilibrium the quantities of the reactants and the products are usually not equal but the rates are, ratio becomes constant. when equilibrium is reached, most of the reactant has been converted to product
what happens as a reaction proceeds
the concentration of the reactants decreases and the reaction slows. the concentrations of the products increases which causes the rate of the reverse reaction to increase.
what is the mass action expression
k = concentration of products over concentrations of reactants. remember that the coefficient determines the exponent.
what does the mass action expression show
the relationshio between the reactants and products in a system at equilibrium.
what is the equilibrium constant
Keq or Kc or Ks
what does it mean if the value of Keq is large
at equilibrium the products are in a greater concentration
what is la chatelier’s principle
if a system at equilibrium is subjected to a stress, it will respond to reduce the stress.
what does a stress do to a reaction
either slows down or speeds up the reverse or forward reaction
what is the effect of concentration on a reaction
- if a concentration of a product increases, the equilibrium will shift in whichever way will decrease the concentration of that substance.
- if the concentration of any reactant or product is decreased, the equilibrium will shift in whatever way will increase the concentration of that substance.
- will not change the equilibrium constant
what is the effect of temperature on equilibrium
- an increase in temp will favor whichever reaction is endothermic
- a decrease in temp will favor whichever reaction is exothermic
- it will change the equilibrium constant.
- f you increase the temperature, the position of equilibrium will move in such a way as to reduce the temperature again
how does pressure affect the equilibrium
- an increase in pressure will increase the rate of whichever reaction produces fewer moles
- a decrease in pressure will increase the rate of whichever reaction produces more moles.
- does not affect the equilibrium constant
how does a catalyst affect the equilibrium
a catalyst will increase the rate of both the forward and reverse reactions equally. equilibrium will be reached more quickly.
