kc

Question 1

how is dynamic equilibrium reached

Answer 1

at the start of the reaction the forward reaction is fast and the backward reaction is slow
after the start the reverse reaction speeds up as the forward reaction slows down
the rate of the forward reaction becomes the same as the rate of forward reaction

Question 2

dynamic meaning

Answer 2

the forward and backward reactions proceed at equal rates and happen simultaneously

Question 3

equilibrium meaning

Answer 3

the concentration of the reactants and products are constant

Question 4

state le chateliers principal

Answer 4

the position of equilibrium will shift to oppose a change made to the system

Question 5

CO + H2O <-> CO2 + H2
if concentration of CO is increased…

Answer 5

the equilibrium will shift to the right to oppose the addition of CO so yeild of CO2 and H2 increases

Question 6

2NO2 <-> N2O4
if pressure is increased

Answer 6

there are fewer moles on the right
the equilibrium shift to the right to oppose the increase in pressure
so yeild of N2O4

Question 7

how does a decrease in volume affect pressure

Answer 7

increase in pressure

Question 8

describe an exothermic reaction

Answer 8

realises heat energy
temperature of surroundings increases
enthaply change is negative

Question 9

CH4 + H2O <-> CO + 3H2
-206KJmol-1

if temperature of the reaction is decreased …

Answer 9

forward reaction is exothermic
the equilibrium shifts to the right to oppose the decreases in temperature
yeild of CO +H2 increases

Question 10

what happens when a catalyst is added reversible reaction

Answer 10

the rate of both the forwards and reverse reactions increase equally
there is no change to the position of the equilibrium
dynamic equilibrium is reached faster

Question 11

why are compromised conditions necessary

Answer 11

higher pressures are too exspensive
45O°C gives a good yeild in a fast time

Question 12

expression for Kc

Answer 12

Kc = [products]/[reactants]

molar ratio is the power

Question 13

what is the meaning of Kc

Answer 13

if Kc is greater then 1 then there are more products than reactants at equilibrium and the equilibrium is shifted to the right

if Kc is less then 1then there are more reactants than products at equilibrium and the equilibrium has shifted to the left

if Kc is exactly 1 then the concentration of the products is equal to the concentration of reactants

Question 14

what affects Kc

Answer 14

pressure doesn’t affect Kc
temp increase = equilibrium shifts endothermic direction