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Flashcards in Equilibrium Deck (31):
0

Reaction shift

A reaction goes the other way
ie synthesis becomes decomposition

1

Reversible

Term for chemical equations that can undergo a reaction shift

2

Dynamic equilibrium

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

3

Equilibrium Constant (k)

Quantifies the concentrations of reactants and products in a reaction

4

Law of Mass Action

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

Coefficients in chemical equations becomes the exponent

5

Evaluation of the equilibrium constant

K>>1 forward reaction is more common

6

Equilibrium constants in reversals

Invert the constant in reversals

7

Equilibrium constant when the chemical equation is multiplied

Multiply the constant by that same factor

8

Equilibrium constant for the elementary step in a reaction mechanism

Multiply the constants together

9

Partial pressure (Kp)

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

10

Reaction quotient (Q)

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)

11

Kc

Standard equilibrium constant
Concentrations of products to their coeffients over reactants to their coeffiecients

12

Concentrations of di-atomic molecules

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

13

Solid and liquid concentrations in Kc

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

14

Reaction progress towards equilibrium (%)

Q/Kc x100%

If >100%, reaction moves backwards towards reactants

15

Relationships between Q and Kc

If QKc, the reaction moves left (towards reactants)
Q=Kc reaction is at equilibrium at that point

16

Graphs of Q

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

17

Law of equlibrium

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

18

Initial→final relationships

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

19

Le chatelier's principal

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)

20

Causing a forwards reaction

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)

21

Causing a reverse reaction

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)

22

Increasing volume on a system at equilibrium

Shifts reaction in the direction of fewest gas particles

23

Increasing temperature on a system at equilibrium

Shifts the reaction in the more exothermic direction

24

Product quantity from Kc

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

25

Equilibrium constant (Kc) from Kp and temperature

Kc=Kp/(RT)^Δn

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

26

Units of Kp and converting

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

27

Converting to K

C=(F-32)/1.8
K=C+273.15

28

Equilibrium constant from Gibbs Free Engergy

Ln(K)=ΔG/(-R*T)

29

Equilibrium constant (k) from standardcell potential

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

30

Calculating concentration from 'k' and time

K=Δ[material]/Δt