Flashcards for JEE Chemistry - Equilibrium Class 11

 Page 1


Equilibrium
Flash cards
Page 2


Equilibrium
Flash cards
Introduction
Equilibrium is a state in which there are no observable 
changes with time
At equilibrium
• Rate of forward reaction (r
f
) = rate of backward reaction (r
b
)
• Concentration of reactants and products remains constant 
with time.
Page 3


Equilibrium
Flash cards
Introduction
Equilibrium is a state in which there are no observable 
changes with time
At equilibrium
• Rate of forward reaction (r
f
) = rate of backward reaction (r
b
)
• Concentration of reactants and products remains constant 
with time.
Properties of chemical equilibrium
• Independent of the direction from which it is attained.
• Dynamic in nature and not static.
• Catalyst can alter the rate of approach of the equilibrium but 
does not change the state of equilibrium.
• ?G = 0
Page 4


Equilibrium
Flash cards
Introduction
Equilibrium is a state in which there are no observable 
changes with time
At equilibrium
• Rate of forward reaction (r
f
) = rate of backward reaction (r
b
)
• Concentration of reactants and products remains constant 
with time.
Properties of chemical equilibrium
• Independent of the direction from which it is attained.
• Dynamic in nature and not static.
• Catalyst can alter the rate of approach of the equilibrium but 
does not change the state of equilibrium.
• ?G = 0
Law of mass action Goldberg & wage 
(Continued)
Rate at which a substance reacts ?? [Active mass of the 
substance]. Generally, active mass is taken to be molarity.
Note : Active mass is unit less while molarity has units of 
moles/lite.
• Active mass for solids and solvents is always taken as '1'.
For a general reaction aA + bB ? cC + dD.
r
f
= k
f
[A]
a
[B]
b
r
b
= k
b
[C]
c
[D]
d
Page 5


Equilibrium
Flash cards
Introduction
Equilibrium is a state in which there are no observable 
changes with time
At equilibrium
• Rate of forward reaction (r
f
) = rate of backward reaction (r
b
)
• Concentration of reactants and products remains constant 
with time.
Properties of chemical equilibrium
• Independent of the direction from which it is attained.
• Dynamic in nature and not static.
• Catalyst can alter the rate of approach of the equilibrium but 
does not change the state of equilibrium.
• ?G = 0
Law of mass action Goldberg & wage 
(Continued)
Rate at which a substance reacts ?? [Active mass of the 
substance]. Generally, active mass is taken to be molarity.
Note : Active mass is unit less while molarity has units of 
moles/lite.
• Active mass for solids and solvents is always taken as '1'.
For a general reaction aA + bB ? cC + dD.
r
f
= k
f
[A]
a
[B]
b
r
b
= k
b
[C]
c
[D]
d
Law of mass action Goldberg & wage
k
c
= equilibrium constant in terms of concentration.
* unit of k
c
= (mole/litre)
(c + d) – (a + b)
* If gaseous components are present k
p
, equilibrium constant 
in terms of partial pressure can be used.
Eg. : aA(g) + bB(g) ? cC(g) + dD(g)
Unit of k
p
= (atm)
??ng
,
??ng = (sum of the stoichiometric coefficient of gaseous 
products) – (sum of the stoichiometric coefficient of gaseous 
reactants)
* k
p
= k
c
(RT)?ng