Equilibrium

Question 0

Reversible

Answer 0

Term for chemical equations that can undergo a reaction shift

Question 1

Reaction shift

Answer 1

A reaction goes the other way

ie synthesis becomes decomposition

Question 2

Dynamic equilibrium

Answer 2

The condition in which the rate of the forward reaction equals the rate of the forward reaction equals the rate of the reverse reaction,
But not the concentrations of the products and reactants

Question 3

Equilibrium Constant (k)

Answer 3

Quantifies the concentrations of reactants and products in a reaction

Question 4

Law of Mass Action

Answer 4

K=(product of individual product concentrations)/(product of individual reactant concentrations)

Coefficients in chemical equations becomes the exponent

Question 5

Evaluation of the equilibrium constant

Answer 5

K»1 forward reaction is more common

Question 6

Equilibrium constants in reversals

Answer 6

Invert the constant in reversals

Question 7

Equilibrium constant when the chemical equation is multiplied

Answer 7

Multiply the constant by that same factor

Question 8

Equilibrium constant for the elementary step in a reaction mechanism

Answer 8

Multiply the constants together

Question 9

Partial pressure (Kp)

Answer 9

Equilibrium pressure of the reaction
Kp=Kc*(RT)^Δn

Δn- |molesProducts-molesReactants|
T- given in Kelvin
Will be expected to calculate all these variables given the others… Need practice

Question 10

Reaction quotient (Q)

Answer 10

Concentrations of the products raised to their stoichiometric coefficients divided by the concentrations of the reactants raised to their stoichiometric coeffients… AT A CERTAIN POINT IN THE REACTION (Kc only applies at equilibrium)

Question 11

Kc

Answer 11

Standard equilibrium constant

Concentrations of products to their coeffients over reactants to their coeffiecients

Question 12

Concentrations of di-atomic molecules

Answer 12

The sub-2 in O2 remains in the conentration-variable box like [O2] and is not raised to a power when calculating Kc

Question 13

Solid and liquid concentrations in Kc

Answer 13

Do not factor in at all when calculating for Kc
Only use the gasses in the reaction,
Their concentrations remain constant regardless of the amount of substance

Question 14

Reaction progress towards equilibrium (%)

Answer 14

Q/Kc x100%

If >100%, reaction moves backwards towards reactants

Question 15

Relationships between Q and Kc

Answer 15

If QKc, the reaction moves left (towards reactants)

Q=Kc reaction is at equilibrium at that point

Question 16

Graphs of Q

Answer 16

Measure the product reactant concentration ratio over a change in (M)
Independent variable runs from 1M-0M for reactants and 0M-1M for products
Usually exponential, Kc represents one horizontal line on that graph, equilibrium when the two meet,
Reactions always move towards that point

Question 17

Law of equlibrium

Answer 17

The natural tendency is towards a concentration of equilibrium
Q will always approach Kc from either direction
(Reverse if greater, forwards if less than)

Question 18

Initial→final relationships

Answer 18

Provide Q with the initial values
Assume that they work towards Kc
Find Kc value (often given) and solve algebraically

Question 19

Le chatelier’s principal

Answer 19

Any disturbance at equilibrium (temperature, volume, mass) and the rest of the system will work to restore equilibrium
(Causes either a forwards or reverse reaction)

Question 20

Causing a forwards reaction

Answer 20

Add concentration to the reactants
Decrease concentration of the products
Increase concentration of the reactants
Increase volume (if products have fewer gas particles)
Decrease volume (if reactants have fewer gas particles)
Increasing temperature (if endothermic)
Decreasing temperature (if exothermic)

Question 21

Causing a reverse reaction

Answer 21

Increase concentration of the products
Decrease concentration of the reactants
Increase volume (if reactants have fewer gas particles)
Decrease volume (if products have fewer gas particles)
Increasing temperature (if exothermic)
Decreasing temperature (if endothermic)

Question 22

Increasing volume on a system at equilibrium

Answer 22

Shifts reaction in the direction of fewest gas particles

Question 23

Increasing temperature on a system at equilibrium

Answer 23

Shifts the reaction in the more exothermic direction

Question 24

Product quantity from Kc

Answer 24

Convert units of reactants to M
Use algebra to solve for product concentration given Kc
Convert [product]M to grams

Question 25

Equilibrium constant (Kc) from Kp and temperature

Answer 25

Kc=Kp/(RT)^Δn

Δn- |molesProducts-molesReactants|
T- given in Kelvin
Will be expected to calculate all these variables given the others… Need practice

Question 26

Units of Kp and converting

Answer 26

Always given as Pascals (Pa)

1 Pa=1N/m^2
        =1/101,325 atm
        =760/101,325 mmHg
        =760/101,325 torr
        =14.7/101,325 psi

Question 27

Converting to K

Answer 27

C=(F-32)/1.8

K=C+273.15

Question 28

Equilibrium constant from Gibbs Free Engergy

Answer 28

Ln(K)=ΔG/(-R*T)

Question 29

Equilibrium constant (k) from standardcell potential

Answer 29

log(K)=E.cell/(0.0592/n

Question 30

Calculating concentration from ‘k’ and time

Answer 30

K=Δ[material]/Δt