Unit 2: Equilibrium

Question 1

Dynamic Equilibrium:

Answer 1

Balance b/t fwd and rev processes occurring at the same rate. Must occur in a closed system.

Question 2

Equilibrium:

Answer 2

When rate of fwd rxn = rate of rev rxn

Question 3

Solubility Equilibrium:

Answer 3

Dynamic equilibrium b/t a solute and solvent in a saturated system. Occurs in a closed system.

Question 4

Phase Equilibrium:

Answer 4

Dynamic equilibrium b/t diff states of a pure substance. Occurs in a closed system.

Question 5

Chemical Equilibrium:

Answer 5

Dynamic equilibrium b/t rxnts and prdts in a chem rxn. Occurs in a closed system.

Question 6

Law of chemical equilibrium:

Answer 6

there is a constant ratio b/t the [C] of rxnts and prdts.

Question 7

Keq (equilibrium constant)

Answer 7

Relationship b/t [c] of prdts over rxnts. Pure substances like (s) or (l) NOT included.

Question 8

When Keq > 1:

Answer 8

Rxn favours the products. If greater than 10^10, the reaction is completed.

Question 9

When Keq = 1:

Answer 9

@ equilibrium.

Question 10

When Keq < 1:

Answer 10

Rxn favours the rxnts. If less than 10^-10, the reaction didn’t occur.

Question 11

Le chateliers principle:

Answer 11

When stress is put on a system at equilibrium, the rxn will shift in the direction that relieves the stress.

Applied stresses: ∆ concentration, ∆ pressure, ∆ temperature

Question 12

Le chateliers principle: Concentration

Answer 12

increase of rxnt [C]: reaction will shift towards the prdts (consume added [c]).

decrease of prdt [C]: reaction will shift towards the prdts (replace lost [c]).

Question 13

Le chateliers principle: Temperture

Answer 13

increase in temp: reaction will shift to consume added heat (right if endo, left if exo)

decrease in temp: reaction will shift to replace the heat (left if endo, right if exo)

Question 14

Le chateliers principle: Pressure

Answer 14

increase in pressure: reaction will shift toward side w/ less molecules.

decrease in pressure: reaction will shift toward side w/ more molecules.

Question 15

Factors that don’t affect equilibrium:

Answer 15

1) adding inert gases
2) adding catalysts

Question 16

Keq if given molar [c] of rxnts & prdts:

Answer 16

Written as Kc.

Question 17

Keq if given gases:

Answer 17

Written as Kp (uses partial pressures).

Question 18

Rxn quotient (Q):

Answer 18

Used if the system is not at equilibrium.

Question 19

If Q > Keq:

Answer 19

equilibrium will shift to the left cuz prdt side is to high.

Question 20

If Q < Keq:

Answer 20

equilibrium will shift to the right cuz rxnt side is to high.

Question 21

I.C.E table:

Answer 21

1) Intial [c]
2) Change (-x or +x)
3) equilibrium

Question 22

Hundred rule:

Answer 22

If Keq is very small (relative to denom) we assume that the [reactant]eq = [reactant]initial

Question 23

Solubility Constant Expression, Ksp:

Answer 23

Eq constant b/t ionic solid and saturated solution. Smaller Ksp = lower the solubility of the ions of an ionic solid. Ksp has only one value at any temp.

Question 24

Reaction quotient (Precipitation): Trial ion Product (Qsp)

Answer 24

Rxn quotient applied to the ion [C] of a slightly soluble salt. Compare value to Ksp to see if precipitate forms.

Question 25

Qsp > Ksp (super saturated)

Answer 25

precipitate will form.

Question 26

Qsp = Ksp (saturated)

Answer 26

precipitate will not form.

Question 27

Qsp < Ksp (unsaturated)

Answer 27

precipitate will not form.

Question 28

Ionization:

Answer 28

A polar covalent compound (acid) breaks up to form new ions as it associates with H2O (irreversible).

Question 29

Dissociation:

Answer 29

Ionic comp breaks apart in a solution (reversible)

Question 30

Bronsted-Lowry Theory of Acids and Bases:

Answer 30

An acid is a substance which loses a proton (H+) to a base. A base is a substance which accepts a proton (H+) from an acid.

Question 31

Conjugate acid:

Answer 31

What remains when a proton is received from a base.

Question 32

Conjugate base:

Answer 32

What remains when a proton is lost from an acid.

Question 33

Amphiprotic:

Answer 33

a molecule or ion that can act as an acid and a base (ex: water).

Question 34

[H3O+] > [OH-]

Answer 34

Acidic soln.

Question 35

[H3O+] = [OH-]

Answer 35

Neutral soln.

Question 36

[H3O+] < [OH-]

Answer 36

Basic soln.

Question 37

pH Scale:

Answer 37

power of hydrogen. measures the amount of H3O+ ions in solution. A change of 1 in the pH = 10x change in the [H3O+].

Question 38

Ion-product Constant of Water, Kw:

Answer 38

As temp increases, Kw (1.0x10^-14) also increases.

Question 39

pOH scale:

Answer 39

power of hydroxide ion concentration → describes the strength of the base in solution.

Question 40

pH, pOH, and pKw relationship:

Answer 40

pKw = -logKw --> Kw = [H3O+][OH-] = 1.0x10^-14 --> pKw = log(1.0x10^-14) = -log[H3O+] + -log[OH-] --> pH + pOH --> 14.

Question 41

Strong acids/bases:

Answer 41

dissociate completely in water to form ions.

Question 42

Weak acids/bases:

Answer 42

dissociates slightly in water to form ions.

Question 43

Monoprotic acid:

Answer 43

a single proton ionizes from an acid.

Question 44

Polyprotic acids:

Answer 44

many acids have more than one proton that can ionize.

Question 45

Strong acid-base:

Answer 45

the CB and CA are weaker so rxn shifts to form weaker CB and CA.

Question 46

Acid ionization constant:

Answer 46

Ka <1 for weak acids.

Question 47

Base ionization constant:

Answer 47

Kb <1 for weak bases.

Question 48

Kw:

Answer 48

= KaKb