what are the factors affecting chemical equilibrium??
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FACTORS AFFECTING CHEMICAL EQUILIBRIUM ARE :
1. (a) Increase in concentration of reactant: by increasing the concentration of reactant, concentration of product increases and hence equilibrium shifts towards forward direction.
(b) Decrease in concentration of reactant: by decreasing the concentration of reactant, concentration of product decreases and hence equilibrium shifts towards backward direction.
2. (a) Increase in concentration of product: by increasing the concentration of product, concentration of reactant increases and hence equilibrium shifts towards backward direction.
(b) Decrease in concentration of product: by decreasing the concentration of reactant, concentration of reactant decreases and hence equilibrium shifts towards forward direction.
3. Temperature: effect of temperature depends on the type of reaction.
TYPE 1 : A + B +Q Kcal ↔ C + D, (ΔH =+ve)
By increasing temperature, equilibrium shifts in forward direction.
By decreasing temperature, equilibrium shifts in backward direction.
TYPE 2 : A + B ↔ C + D + Q Kcal
By increasing temperature, equilibrium shifts in backward direction.
By decreasing temperature, equilibrium shifts in forward direction.
TYPE 3 : when ΔH = 0 or A + B ↔ B + D
In this case there will be no effect of temperature on chemical equilibrium.
4. Pressure: By increasing pressure, equilibrium shifts towards that direction in which volume decreases of number of moles of gas decreases.
By decreasing pressure, equilibrium shifts towards that direction in which volume increases of number of moles of gas increases.
5. Addition of noble gas
hope it helps!!
1. (a) Increase in concentration of reactant: by increasing the concentration of reactant, concentration of product increases and hence equilibrium shifts towards forward direction.
(b) Decrease in concentration of reactant: by decreasing the concentration of reactant, concentration of product decreases and hence equilibrium shifts towards backward direction.
2. (a) Increase in concentration of product: by increasing the concentration of product, concentration of reactant increases and hence equilibrium shifts towards backward direction.
(b) Decrease in concentration of product: by decreasing the concentration of reactant, concentration of reactant decreases and hence equilibrium shifts towards forward direction.
3. Temperature: effect of temperature depends on the type of reaction.
TYPE 1 : A + B +Q Kcal ↔ C + D, (ΔH =+ve)
By increasing temperature, equilibrium shifts in forward direction.
By decreasing temperature, equilibrium shifts in backward direction.
TYPE 2 : A + B ↔ C + D + Q Kcal
By increasing temperature, equilibrium shifts in backward direction.
By decreasing temperature, equilibrium shifts in forward direction.
TYPE 3 : when ΔH = 0 or A + B ↔ B + D
In this case there will be no effect of temperature on chemical equilibrium.
4. Pressure: By increasing pressure, equilibrium shifts towards that direction in which volume decreases of number of moles of gas decreases.
By decreasing pressure, equilibrium shifts towards that direction in which volume increases of number of moles of gas increases.
5. Addition of noble gas
hope it helps!!
computer11:
thank you so much
ur wlcm
Answered by
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hell.. ooo....
Le Chatelier's Principle: If a system at equilibrium is disturbed by an external stress, the
system adjusts to partially offset the stress as the system attains a new equilibrium position.
Changes in Concentration
⇒ Adding a reactant or product, the equilibria shifts away from the increase in order to
consume part of the added substance.
⇒ Removing a reactant or product, the equilibria shifts toward the decrease to replace part of
the removed species.
E.g. For H2 + I2 2HI, does the equilibria shift left or right if we: a) add H2? b) remove I2?
a)
b)
Changes in Volume and Pressure
Because the pressure of gases is related directly to the concentration by P = n/V, changing the
pressure by increasing/decreasing the volume of a container will disturb an equilibrium system.
⇒ If P increases (V decreases), the system shifts to the side with a smaller number of gas
molecules (this effectively reestablishes equilibrium by decreasing the pressure).
⇒ If P decreases (V increases), the system shifts to the side with a greater number of gas
molecules.
Example. For N2(g) + 3H2(g) 2NH3(g), does the equilibrium shift left or right if the pressure is
increased?
Changes in Temperature
Heat can be considered a reactant in an endothermic rxn and a product in an exothermic rxn.
Endothermic (∆H > 0) R + Heat Products
Exothermic (∆H < 0) R Products + Heat
Recall that both Kc and the position of the equilibrium system will vary with temperature:
• Kc is larger when the reaction shifts right. This occurs if T is increased for an
Endothermic Reaction or T is decreased for an Exothermic reaction.
• Kc is smaller when the reaction shifts left. This occurs if T is decreased for an
Endothermic Reaction or T is increased for an Exothermic reaction.
Example. If the temperature is decreased for the reaction: 2CO2 2CO + O2, ∆H = 566 kJ.
a) Will the equilibrium shift left or right? b) Does Kc become larger or smaller?
Effect of a Catalyst
⇒ Catalysts lower Ea for the reaction, so a catalyst decreases the amount of time taken to reach
equilibrium for both the forward and reverse reactions.
⇒ The catalyst does not affect the equilibrium concentrations of reactants and products in the
equilibrium mixture; thus, the Kc value does not change.
Choosing Optimum Conditions
Le Chatelierís principle can be used to select optimum conditions to form a substance.
e.g. To form more NH3, predict the optimum conditions for temperature and pressure.
N2(g) + 3H2(g) 2NH3(g) ∆H = -91.8 kJ
Le Chatelier's Principle: If a system at equilibrium is disturbed by an external stress, the
system adjusts to partially offset the stress as the system attains a new equilibrium position.
Changes in Concentration
⇒ Adding a reactant or product, the equilibria shifts away from the increase in order to
consume part of the added substance.
⇒ Removing a reactant or product, the equilibria shifts toward the decrease to replace part of
the removed species.
E.g. For H2 + I2 2HI, does the equilibria shift left or right if we: a) add H2? b) remove I2?
a)
b)
Changes in Volume and Pressure
Because the pressure of gases is related directly to the concentration by P = n/V, changing the
pressure by increasing/decreasing the volume of a container will disturb an equilibrium system.
⇒ If P increases (V decreases), the system shifts to the side with a smaller number of gas
molecules (this effectively reestablishes equilibrium by decreasing the pressure).
⇒ If P decreases (V increases), the system shifts to the side with a greater number of gas
molecules.
Example. For N2(g) + 3H2(g) 2NH3(g), does the equilibrium shift left or right if the pressure is
increased?
Changes in Temperature
Heat can be considered a reactant in an endothermic rxn and a product in an exothermic rxn.
Endothermic (∆H > 0) R + Heat Products
Exothermic (∆H < 0) R Products + Heat
Recall that both Kc and the position of the equilibrium system will vary with temperature:
• Kc is larger when the reaction shifts right. This occurs if T is increased for an
Endothermic Reaction or T is decreased for an Exothermic reaction.
• Kc is smaller when the reaction shifts left. This occurs if T is decreased for an
Endothermic Reaction or T is increased for an Exothermic reaction.
Example. If the temperature is decreased for the reaction: 2CO2 2CO + O2, ∆H = 566 kJ.
a) Will the equilibrium shift left or right? b) Does Kc become larger or smaller?
Effect of a Catalyst
⇒ Catalysts lower Ea for the reaction, so a catalyst decreases the amount of time taken to reach
equilibrium for both the forward and reverse reactions.
⇒ The catalyst does not affect the equilibrium concentrations of reactants and products in the
equilibrium mixture; thus, the Kc value does not change.
Choosing Optimum Conditions
Le Chatelierís principle can be used to select optimum conditions to form a substance.
e.g. To form more NH3, predict the optimum conditions for temperature and pressure.
N2(g) + 3H2(g) 2NH3(g) ∆H = -91.8 kJ
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