7 equilibrium

Question 1

in a dynamic equilibrium?

Answer 1

the rate of the forward reaction is the SAME as the rate of the backward reaction in a CLOSED system
and the conc of reactants and products is CONSTANT

Question 2

graph of reaching equilibrium from reactants and from products

Answer 2

curved line up like an r + curved line down like an L until both cross and are constant
– reactants form products until eq

conc of reactants incr, conc of products decr

Question 3

closed vs open system

Answer 3

closed: no reactant can escape the mixture

open: some is lost to surroundings (so the reaction is technically not reversed)

Question 4

in an equilibrium expression, is reactants/prod or prod/reactants?

Answer 4

prod/reactants

Question 5

in an equilibrium expression, the coefficient is?

Answer 5

added as a power of the conc

Question 6

in an equilibium expression, what is not included from the chemical equation?

Answer 6

SOLIDS!!! NO SOLIDS

WE FUCKING HATE SOLIDS ok when you think abt it the particles cant rearrange so

Question 7

what is Kc dependent on?

Answer 7

temperature

so at a fixed temp Kc is a constant

Question 8

when Kc > 1,

Answer 8

equilibium shifts to the right,
more products

Question 9

Kc for
N2 + 3 H2 == 2NH3
vs (doubled)
2N2 + 6H2 == 4NH3

Answer 9

the first Kc to the POWER of 2 is the new Kc

Question 10

calculating Kc for the reverse equation? hwo does this affect the Kc

Answer 10

reverse Kc = 1/og Kc

Question 11

what is the reaction quotient

Answer 11

ratio of products and reactats for a reaction that has NOT YET reached equilibrium

Question 12

what does the size of the reaction quotient tell us

Answer 12

how far a reaction is from equilibiurm

which direction the reaction proceeds

Question 13

what is the position of equilibrium

Answer 13

refers to the relative amts of products and reactants in an equilibrium mixture

Question 14

what is Le Chatelier’s principle

Answer 14

says that if a CHANGE is made to a system at DYNAMIC EQUILIBRIUM,
position of equilibrium MOVES to minimise this change
(not required to quote but must APPLY)

Question 15

increase in reactants conc effect on equilibrium

Answer 15

shifts RIGHT (= more product)

Question 16

effects of increase in pressure on equilibrium

Answer 16

shifts in direction that produces SMALLER number of molecules of gas

Question 17

effect of incr temperature on equilbirum shift

Answer 17

equilibrium moves in the ENDOTHERMIC direction to reverse the change

change in H = +
means forward is favoured (endo)

Question 18

effect of catalyst on forward and backward reactions

Answer 18

incr rate EQUALLY
= reach equilibirum FASTER

Question 19

is the equilibrium constant affected by changes to reactant/product concentration???

Answer 19

NOOOOOOO
but the opposite reaction is favoured until equilibrium is restored

Question 20

does change in pressre affect Kc?????

Answer 20

NOOOO
its only changes the POSITION of equilibrium

Question 21

do temp changes affect equilibrium constant

Answer 21

of COURSE they do
Kc increases with an endothermic reaction (+)

Question 22

is Kc or position of equilibium affected by change in concnetration

Answer 22

position

Question 23

chemical equaiton for the Haber Process

Answer 23

N2 (g) + 3H2 (g) <==> 2NH3 (g)

Question 24

given the eqn for the haber process, N2 (g) + 3H2 (g) <==> 2NH3 (g)

how will increasing nitrogen amt affect:
1. position of equilibium
2. amount of ammonia
3. amount of hydrogen
4. Kc

Answer 24

1. right
2. incr
3. decr
4. unchanged

new equilibrium would be higher than original

Question 25

what do [ ] mean in Kc calculations

Answer 25

the conc of the chemical in mol/dm3

Question 26

what is the chemical formula of ethanoic acid

Answer 26

CH3COOH

Question 27

how to deduce units for Kc

Answer 27

subsitute the units for the concs into the equation and cancel out

if its like mol/dm3 divided by mol/dm3 then yeah no units

Question 28

equation for Gibbs free energy change? (section 1 data booklet)

Answer 28

gibbs free energy change = -(gas constant)(temp in K) ln(equilibium constant)

Question 29

what are the units for Gibbs free energy change and R (gas constant)?

Answer 29

G –> kJ / mol
R –> J /K/mol

= one value needs to be adjusted by 1000

Question 30

when equilibrium constant > 1, gibbs free energy change?

Answer 30

ΔG < 0

Question 31

when Kc = 0, gibbs free energy change?

Answer 31

ΔG = 0

Question 32

a negative ΔG value means the reaction is (spontaneous/non-spontaneous)

Answer 32

spontaneous!

Question 33

as ΔG becomes more negative
the forward reaction is?
the value of the equilibium constant?

Answer 33

forward favoured

Kc increases

Question 34

to find Kc from lnKc = 1.77?

Answer 34

lnKc = 1.77

Kc = e ^ 1.77