Equilibrium Unit

Question 1

What is dynamic equilibrium

Answer 1

a state of balance between two opposite processes taking place at the same rate

Question 2

what is physical equilibria

Answer 2

phase equilibrium, solution equilibrium, and vapor liquid equilibrium

Question 3

what is phase equilibrium

Answer 3

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

Question 4

what is solution equilibrium

Answer 4

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.

Question 5

what is vapor liquid equilibrium

Answer 5

the rate of evaporation will equal the rate of condensation. the number of particles becomes constant and also the vapor pressure.

Question 6

what is chemical equilibrium

Answer 6

occurs only in reversible reactions. the forward and reverse reaction must occur at the same time. has to be in a closed system

Question 7

what are the concentrations of the products/reactions generally like

Answer 7

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

Question 8

what happens as a reaction proceeds

Answer 8

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.

Question 9

what is the mass action expression

Answer 9

k = concentration of products over concentrations of reactants. remember that the coefficient determines the exponent.

Question 10

what does the mass action expression show

Answer 10

the relationshio between the reactants and products in a system at equilibrium.

Question 11

what is the equilibrium constant

Answer 11

Keq or Kc or Ks

Question 12

what does it mean if the value of Keq is large

Answer 12

at equilibrium the products are in a greater concentration

Question 13

what is la chatelier’s principle

Answer 13

if a system at equilibrium is subjected to a stress, it will respond to reduce the stress.

Question 14

what does a stress do to a reaction

Answer 14

either slows down or speeds up the reverse or forward reaction

Question 15

what is the effect of concentration on a reaction

Answer 15

• 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

Question 16

what is the effect of temperature on equilibrium

Answer 16

• 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

Question 17

how does pressure affect the equilibrium

Answer 17

• 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

Question 18

how does a catalyst affect the equilibrium

Answer 18

a catalyst will increase the rate of both the forward and reverse reactions equally. equilibrium will be reached more quickly.