Equilibria: Introduction to Equilibrium | A-level Chemistry | OCR, AQA, Edexcel
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5 سال پیش
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Equilibria: Introduction to Equilibrium in
Equilibria: Introduction to Equilibrium in a Snap!
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The key points covered in this video include:
1. What are reversible reactions?
2. Analogy: Dynamic Equilibrium
3. The Position of equilibrium
4. Features of a Dynamic Equilibrium
5. Changing the Position of Equilibrium
a) Changing Temperature
b) Changing Concentration
c) Changing Pressure
d) Presence of a Catalyst
What are Reversible Reactions?
Reversible reactions are at equilibrium. Although nothing appears to be happening, The system is constantly moving. It is Dynamic, A reversible reaction is only completely dynamic when it is isolated, Nothing is put in or taken out of our system.
Analogy: Dynamic Equilibrium
If you hang your washing out to dry on the line. It begins to rain. The rate at which your clothes are drying off and the rate at which they are getting wet are the same. This is an equilibrium.
Features of a Dynamic Equilibrium
At the same time: Reactants are being converted to Products, Products are being converted to Reactants. A chemical system is in dynamic equilibrium when: The concentration of reactants and products is constant, The rate of forward reaction is the same as the rate of the reverse reaction.
The Position of the Equilibrium
The extent of the reaction is the position of the equilibrium.
Changing the Position of the Equilibrium
Le Chatelier’s Principle states that: When a system in dynamic equilibrium is subjected to change, the position of the equilibrium will shift to minimise the change. The system will move to minimise any change to the position of the equilibrium. It will move to carry out the Forward/Reverse reaction more. We can alter the position of the equilibrium by changing: Temperature, Concentrations of the Reactants/Products, Pressure in Reactions involving Gasses.
Position of Equilibrium: Changing Temperature
The effect of a change in temperature on the position of the equilibrium will depend on the enthalpy of the reaction. The forward reaction: ΔH is -ve, Exothermic reaction.The backward reaction: ΔH is +ve, Endothermic reaction. Increasing the temperature will cause the system to move to oppose this change. It will move in the endothermic direction, The system will move to the left.
Position of Equilibrium: Changing Concentration
A change in concentration of either products or reactants will cause a change in the position of the equilibrium. Increasing the concentration of a reactant or product will cause the equilibrium to shift to oppose this change. Shift to decrease this concentration.
Position of Equilibrium: Changing Pressure
Changing the pressure of a system will only change the position of the equilibrium of the reaction involves gases. Increasing the pressure of the system will cause it to move to the side with fewest moles of gases. Decreasing the pressure of the system will cause it to move to the side with greatest moles of gases. e.g. L: 4 moles, R: 2 moles. Increasing the pressure will cause the system to move to the right.
Position of Equilibrium: Catalyst
Adding a catalyst does not change the position of the equilibrium. A catalyst increases the rate of the forwards and backwards reaction equally, It will increase the rate at which the equilibrium is established, It does not alter the position of the equilibrium.
Unlock the full A-level Chemistry course at http://bit.ly/2ZMub0J created by Ella Buluwela, Chemistry expert at SnapRevise.
SnapRevise is the UK’s leading A-level and GCSE revision & exam preparation resource offering comprehensive video courses created by A* tutors. Our courses are designed around the OCR, AQA, SNAB, Edexcel B, WJEC, CIE and IAL exam boards, concisely covering all the important concepts required by each specification. In addition to all the content videos, our courses include hundreds of exam question videos, where we show you how to tackle questions and walk you through step by step how to score full marks.
Sign up today and together, let’s make A-level Chemistry a walk in the park!
The key points covered in this video include:
1. What are reversible reactions?
2. Analogy: Dynamic Equilibrium
3. The Position of equilibrium
4. Features of a Dynamic Equilibrium
5. Changing the Position of Equilibrium
a) Changing Temperature
b) Changing Concentration
c) Changing Pressure
d) Presence of a Catalyst
What are Reversible Reactions?
Reversible reactions are at equilibrium. Although nothing appears to be happening, The system is constantly moving. It is Dynamic, A reversible reaction is only completely dynamic when it is isolated, Nothing is put in or taken out of our system.
Analogy: Dynamic Equilibrium
If you hang your washing out to dry on the line. It begins to rain. The rate at which your clothes are drying off and the rate at which they are getting wet are the same. This is an equilibrium.
Features of a Dynamic Equilibrium
At the same time: Reactants are being converted to Products, Products are being converted to Reactants. A chemical system is in dynamic equilibrium when: The concentration of reactants and products is constant, The rate of forward reaction is the same as the rate of the reverse reaction.
The Position of the Equilibrium
The extent of the reaction is the position of the equilibrium.
Changing the Position of the Equilibrium
Le Chatelier’s Principle states that: When a system in dynamic equilibrium is subjected to change, the position of the equilibrium will shift to minimise the change. The system will move to minimise any change to the position of the equilibrium. It will move to carry out the Forward/Reverse reaction more. We can alter the position of the equilibrium by changing: Temperature, Concentrations of the Reactants/Products, Pressure in Reactions involving Gasses.
Position of Equilibrium: Changing Temperature
The effect of a change in temperature on the position of the equilibrium will depend on the enthalpy of the reaction. The forward reaction: ΔH is -ve, Exothermic reaction.The backward reaction: ΔH is +ve, Endothermic reaction. Increasing the temperature will cause the system to move to oppose this change. It will move in the endothermic direction, The system will move to the left.
Position of Equilibrium: Changing Concentration
A change in concentration of either products or reactants will cause a change in the position of the equilibrium. Increasing the concentration of a reactant or product will cause the equilibrium to shift to oppose this change. Shift to decrease this concentration.
Position of Equilibrium: Changing Pressure
Changing the pressure of a system will only change the position of the equilibrium of the reaction involves gases. Increasing the pressure of the system will cause it to move to the side with fewest moles of gases. Decreasing the pressure of the system will cause it to move to the side with greatest moles of gases. e.g. L: 4 moles, R: 2 moles. Increasing the pressure will cause the system to move to the right.
Position of Equilibrium: Catalyst
Adding a catalyst does not change the position of the equilibrium. A catalyst increases the rate of the forwards and backwards reaction equally, It will increase the rate at which the equilibrium is established, It does not alter the position of the equilibrium.
5 سال پیش
در تاریخ 1398/06/10 منتشر شده
است.
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