This presentation discusses chemical equilibrium, including: 1) Reversible reactions where reactants form products and vice versa under the same conditions, versus irreversible reactions where the reverse reaction does not occur. 2) Chemical equilibrium being reached when the forward and reverse reaction rates are equal and concentrations do not change over time. 3) The equilibrium constant K relating concentrations or pressures of products over reactants at equilibrium. 4) The relationship between the concentration constant Kc and pressure constant Kp for gas reactions. 5) Homogeneous equilibrium involving one phase and heterogeneous equilibrium involving multiple phases.

1. Presentation Topic:Chemical Equilibrium
Present to
Name: Md. Mohin Uddin
Lecturer
Department of Textile
Engineering
Course code: CHE 101
Presented by
Name Id
Md.Torikul Islam 221002057
Md.Iftekhar Ul Alam 221002059
Forkan Hossen Noman 221002301
Department : Department of CSE
Batch : 221 (Day) Group:08
Section: CHE 101 (D11)

2. Content
 Reversible Reaction
 Irreversible reactions
 Chemical Equilibrium
The Equilibrium constant
 Relationship between 𝐾𝑐 and 𝐾𝑝
 Types Of Chemical Equilibrium

3. Reversible Reaction
A reaction in which reactants react to form products and at
the same time the products react to from reactants under the
same conditions is called reversible reactions.
In general, A+B C+D
E.g. 𝑁2(𝑔) + 3𝐻2(𝑔) 2𝑁𝐻3(𝑔)

4. Irreversible reactions
A reaction that takes in forward direction reactants forming
products but the reverse reaction does not take place is called an
irreversible reaction.
Example:
𝐴𝑔𝑁𝑂3(𝑎𝑞) + 𝑁𝑎𝐶𝑙(𝑎𝑞) 𝐴𝑔𝐶𝑙(𝑠) + 𝑁𝑎𝑁𝑂3(𝑎𝑞)
2𝑀𝑔(𝑠)+ 𝑂2(𝑔) 2𝑀𝑔𝑂(𝑠)

5. Chemical Equilibrium
Chemical equilibrium may be defined as: the state of a reversible
reaction when the two opposing reactions occur at the same rate and
the concentrations of reactants and products do not change with time.
Figure: At Equilibrium the forward reaction rate equals the reverse reaction rate.

6. Md.Iftekhar Ul Alam
Id:221002059

7. The Equilibrium constant
To generalize this expression, consider the reaction
aA + bB cC + dD
The equilibrium expression for this reaction would be
𝐾𝑐=
[𝐶]𝑐[𝐷]𝑑
[𝐴]𝑎[𝐵]𝑏 K =
𝒑𝒓𝒐𝒅𝒖𝒄𝒕𝒔
𝒓𝒆𝒂𝒄𝒕𝒂𝒏𝒕𝒔

8. The Equilibrium constant
𝑁2𝑂4(𝑞) 2𝑁𝑂2(𝑞)
Forward Reaction Reverse Reaction
𝑁2𝑂4(𝑞) 2𝑁𝑂2(𝑞) 𝑁2𝑂4(𝑞) 2𝑁𝑂2(𝑞)
2𝑁𝑂2(𝑞) 𝑁2𝑂4(𝑞)
Rate Law Rate Law
rate = 𝑘𝑓[𝑁2𝑂4] rate = 𝑘𝑟[𝑁𝑂2]2

9. The Equilibrium constant
At equilibrium,
𝑟𝑎𝑡𝑒 𝑓 = 𝑟𝑎𝑡𝑒 𝑟
k𝑓 [𝑁2𝑂4] = 𝑘𝑟[𝑁𝑂2]2
Rearranging gives:
k𝑓
𝑘𝑟
=
[𝑁𝑂2]2
[𝑁2𝑂4]

10. The Equilibrium constant
Because pressure is proportional to concentration for gases
in a closed system, the equilibrium expression can also be
written in terms of partial pressures
𝐾𝑝=
( 𝑃𝐶)𝑐( 𝑃𝐷)𝑑
( 𝑃𝐴)𝑎( 𝑃𝐵)𝑏

11. Forkan Hossen Noman
Id:221002301

12. Relationship between 𝑲𝒄 and 𝑲𝒑
From the ideal gas law we know that,
PV = nRT
P =
𝑛
𝑉
RT = Pressure in terms of concentration
𝑃𝐴 =
𝑛𝐴
𝑉
RT = [A]RT

13. Relationship between 𝑲𝒄 and 𝑲𝒑
Substituting P=[A]RT into the expression for K, for each substance,
the relationship between K, and K, becomes
𝐾𝑝 = 𝐾𝑐(𝑅𝑇)∆𝑛
Where:
∆𝑛 = (moles of gaseous product) − (moles of gaseous reactant)
Hint: 'products-reactants' and 'products over reactants' is a common theme in
chemistry.

14. Types Of Chemical Equilibrium
Homogeneous equilibrium: In a homogeneous system, all the
reactants and products are in the same phase.
For e.g
𝑁2(𝑞) + 3𝐻2(𝑞) 2𝑁𝐻3(𝑔)
In this gaseous reaction, reactants and products are in the
homogeneous phase(all are in gaseous phase).

15. Types Of Chemical Equilibrium
Heterogeneous equilibrium: when equilibrium reaction has its
reactants and products in different phases, it is termed as
heterogeneous equilibrium.
• The equilibrium between water vapour and liquid water in a closed
container is an example of heterogeneous equilibrium.
H₂O(1) H₂O(g)

16. THANK YOU