Chapter 13

Question 1

equilibrium

Answer 1

• the state where the concentrations of all reactants and products remain constant with time
• this does not mean there is no activity
• there is just no net change
• concentrations of the reactants never go to zero, they’ll just be in small but constant concentrations
• the concentrations of all reactants and products remain constant because forward and reverse reactions rates are equal (molecules react by colliding with one another, and the more collisions, the faster the reaction)

Question 2

equilibrium constant

Answer 2

• Kc or K
• it’s concentration is in molarity (moles /volume)
• its the equilibrium constant at an given constant temperature
• IT DOES NOT HAVE UNITS

Question 3

law of mass action

Answer 3

-if you know something in that form, it equals Kc

Question 4

when writing the equation for equilibrium constant

Answer 4

• do not include solids or liquids because the concentration and molarity is constant
• only include gas, aqueous, and ions

Question 5

if the balanced equation is multiplied by a factor n

Answer 5

-the equilibrium is the original expression raised to the nth power.

Question 6

if the balanced equation is reverse

Answer 6

-the new equilibrium is 1/k of the original equilibrium (look in book)

Question 7

if the balanced equation is multiplied by 1/2

Answer 7

-Kc to the 1/2

Question 8

if k > 1

Answer 8

• favor the products

- more products

Question 9

if k < 1

Answer 9

• favour reactants

- more reactants

Question 10

Kp

Answer 10

• equilibrium constant in terms of partial pressures
• ONLY WRITTEN AS Kp
• Kp = Kc(RT) squared delta n

Question 11

n in Kp = Kc(RT) squared delta n

Answer 11

-number of mol gas products - number of mol gas reactants

Question 12

homogeneous equilibria

Answer 12

• equilibria for systems in the gas phase

- all reactants and products are gases

Question 13

heterogeneous equilibria

Answer 13

• involve more than one phase

- the Kc is only the

Question 14

reaction quotient (Q)

Answer 14

• it is obtained by applying the law of mass action using initial concentrations instead of equilibrium concentrations
• there are three different ways an equilibrium can shift
  1. q is equal to k (no shift)
  2. q is greater than k (ratio of initial concentrations of products to reactants is too large, shifts to left or consume products and form reactants)
  3. q is less than k (ratio of initial concentrations of products of reactants is too small, shift to right or form products and consumes reactants)

Question 15

le chatelier’s principle

Answer 15

• if an change is imposed on an system at equilibrium, the position of the equilibrium will shift in an direction that tends to reduce that change
• if an component is added to an reaction system at equilibrium (at constant T and P or constant T and V) the equilibrium position will shift in the direction that lowers the concentration of that component. If an component is removed,the opposite effect occurs
• the system shifts in the direction that compensate for imposed change

Question 16

three ways to change the pressure of an reactionary system involving gaseous components

Answer 16

• add or remove an gaseous reactant or product
• add an inert gas (one not involved in the reaction)
• change the volume of the container

Question 17

the effect of adding an inert gas

Answer 17

-it increases the total pressure but has no effect on the concentrations or partial pressures of the reactants or products

Question 18

the effect of changing the volume of the container

Answer 18

• concentrations (and thus partial pressures) are changed
• when the the volume is reduce, the system responds by reducing its own volume by decreasing total number of gaseous molecules in the system (equilibrium position will shift toward side of the reaction involving smaller number of gaseous molecules in the balanced equation

Question 19

the effect of an change in temperature

Answer 19

• the value of K changes with temperature
• treat energy as an reactant (in an endothermic process) and predict the direction of the shift in the same way as when and actual reactant or product is added or removed
• treat energy as an product (in an exothermic process) and predict the direction of the shift in the same way as when and actual reactant or product is added or removed

Question 20

how do you treat energy (in an endothermic process) ?

Answer 20

-reactant

Question 21

how do you treat energy ((in an exothermic process)?

Answer 21

-product

Question 22

when the temperature is positive…..

Answer 22

-endothermic

Question 23

when the temperature is negative….

Answer 23

-exothermic

Question 24

adding water (blue)

Answer 24

turns pink

Question 25

adding hydrochloric acid and calcium chloride

Answer 25

turns blue

Question 26

adding silver nitrate

Answer 26

turns pinks

Question 27

heating up solution

Answer 27

turns blue

Question 28

cooling down solution

Answer 28

turns pink

Question 29

endothermic

Answer 29

increased temp … cause to shift to right and K increase

Question 30

exothermic

Answer 30

increased temp … cause shift to left and K decrease