Equilibrium Systems

Question 1

Graphing reversible reactions

Answer 1

Lines meet in middle: state of dynamic equ. in which the r(forward) = r(reverse) [rate/time]
Lines cross and level out: concentrations of reactant and products remain constant over tiime [amount/time]

Question 2

What does an eq system look like?

Answer 2

Macroscopic properties (colour, pressure, temp, [ ], ph) remain constant
Microscopically something is happening there is a dynamic change at the molecular level.

Question 3

Types of dynamic eq

Answer 3

Solubility eq, Phase eq, Chem eq.

Question 4

Solubility Equilibrium

Answer 4

undissolved and dissolved solute in a saturated solution in a closed system. Exists when a chemical compound in (s) state is in chemical eq with a solution of that compound.

Question 5

Phase Equilibrium

Answer 5

between 2 physical states of a pure substance in a closed system

Question 6

Chemical Equilibrium

Answer 6

reactants and products of a chem rxn in a closed system

Question 7

How to calculate Equilibrium Concentration?

Answer 7

Stoichiometry to determine [react] or [prod] organised using a RICE table

Question 8

RICE Table

Answer 8

R = mole ratio
I = initial [react] and [prod]
C = stoichiometric change in [ ] (see mole ratio)
E = equilibrium [react] and [prod] ( I + C )

Question 9

Equilibrium Law Expression

Answer 9

K = [C]^c [D]^d / [A]^a [B]^b

[does not include (s) or (l)]

Question 10

Relation between k and K

Answer 10

r(f) = k(f) [A]^a [B]^b
r(r) = k(r) [C]^c [D]^d
K = k(f) / k(r) As temp changes so does value of K

Question 11

Magnitude of K?

Answer 11

K>1 : more products @ eq
K about 1 : equal amounts of react + prod
K<1 : more reactants @ eq

Question 12

Reaction Quotient

Answer 12

Q = [C]^c [D]^d / [A]^a [B]^b
If Q = K system @ eq
If Q>K system needs to shift left
If Q

Question 13

Le Chatelier’s Principle

Answer 13

When you stress/disturb an eq system (by [ ], volume, temp, add chemical that reacts with R or P) it will shift to return to eq.

Question 14

Stress: Change [ ]

A B

Answer 14

Increase [A] shifts right, Increase [B] shifts left

No effect on K

Question 15

Stress : Change Temp

Answer 15

Endo (energy as react), Increase energy, shifts right
k(f) inc - K inc
Exo (energy as prod), Increase energy, shifts left
k(r) inc - K decreases
Exo, increase temp (energy), shifts left
k(r) inc - K decreases
Exo, decrease temp, shifts right
k(f) inc - K inc

Question 16

Solubility

Answer 16

A measure in the amount of a substance that will dissolve in a given volume of solvent at a given temp. A saturated solution is when no more solute can be dissolved.

Question 17

Molar Solubility

Answer 17

Measures solubility in mols/L of a saturated solution.

Question 18

K

Answer 18

Solubility product constant. Obtained from the eq law expression of a saturated solution.

Question 19

How to predict a ppte?

Answer 19

One product must be slightly soluble or insoluble in water. Ions must be high enough to produce visible ppte.

Question 20

Trial Ion Product [Q(sp)]

Answer 20

Indicates if a ppte will form when solutions of metal cations and non-metal anions are mixed.
If QKsp : [ions] exceeds tht which is possible for a saturated solution and ppte will form.

Question 21

Common Ion Effect

Answer 21

Solubility of a salt is reduced due to the presence of another salt having a common ion. Ksp describes the solubility of a system. Incorporates Le Chatelier’s Principle. When solving for x(x)^2 test assumption if x is insignificant.