3.3 - Reversible Reaction and Equilibrium Flashcards
What are reversible reaction?
A reversible reaction is one that can go both ways reactants form products and products can react to form reactants.
What is the Dehydration of Copper(II) Sulfate crystals?
If you heat blue Copper(II) sulfate crystals crystals gently, the blue crystals turn to a white powder and water is driven off. Heating causes the crystals to lose their water of crystallisation and white anhydrous copper(II) sulfate is formed anhydrous is without water.
CuSO45H2O > CuSO4 + 5H2O Heat is required for this reaction
If you add water to the white solid it turns blue again and becomes warm
CuSO4 + 5H20 > CuSO45H20 >
Original change has been reversed even he heat that has been put is has been given out again. This is a reversible reaction
How is Heating Ammonium Chloride a revisable reaction?
When heating ammonium chloride white crystals disappear from the bottom of the tube and reappear further up. Heating ammonium chloride splits it into the colourless gases ammonia and hydrogen chloride.
NH4CL > NH3 +HCL Heat is required for this reaction to occour
NH3 + HCL > NH4CL Heat is released from this reaction
The reaction reverses when the conditions are changed from hot to cold
How are there Reversible reactions in a sealed container?
A sealed container means no substance are added to the reaction mixture and no substances can escape heat can be given of or absorbed.
This is because the forward reaction is proceeding at exactly the same rate as revisable. Its now described as state of equilibrium.
What is dynamic equilibrium?
The concentration of the reactants and products are constant. The concentrations do not have to be the same as one another but they are a fixed ratio
The reaction is still proceeding
The rate of the forward reaction = The rate of the reversible reaction.
Dynamic meaning active so even though the reaction has reached an equilibrium the reaction is still proceeding.
How is dynamic equilibrium reached
1.There is only reactants at the start of a reaction
A+B >
2.The rate of forwards reaction is greater than the rate of backwards reaction because there are more reactants than products. We say the position of equilibrium lies to the left.
3.The rate of the backwards reaction increases as the level of C and D increases. The rate of the forwards reaction decreases as the reactants get used up
- The rates of the forward and backwards reactions eventually become equal = equilibrium
3.
What is a closed system?
No products or reactants can escape from the system
What is equilibrium defined as?
Equilibrium means the concentration of the reactants and products in a reversible reaction remain constant. Dynamic means the reactions are still continuing, but the rate of forward reaction is equal to the rate of the reverse reaction.
What does a graph look like when it is in equilibrium
What are the factors used to influence the position of equilibrium?
Changing pressure
Changing tempreture
Adding a catalyst
Changing concentration of reactants or products.
How does changing the pressure affect the position of equilibrium?
When increasing the pressure the reaction will respond by reducing it again. It can reduce it by producing fewer gaseous molecules to hit the walls of the container. Increasing the pressure will always cause the position of equilibrium to shift to the side with fewer gas molecules this decreases the pressure
Decreasing the pressure will cause the position of equilibrium to shift to the side with more gas molecules.
How does changing the concentration have on the position of equilibrium?
Increasing concentration of the reactants will cause the position of equilibrium to shift to the forward reaction (Right) in order to decrease the concentration of the reactants so that equilibrium is reached again/ This will result in an increase in the yield of the products
Decreasing the conc of the reactants shifts to the left revisable reaction to decrease the yield of the products
Increasing conc of product shift to left.
Decrease conc of product shift to right.
What effect does changing the tempreture have on the position of equilibrium?
Exothermic:
Decreasing the temp will shift the position of equilibrium to the right as the systems tries to increase the tempreture to reach equilibrium so will shift to exothermic reaction heat energy is released so the temp increase yield of the products.
Increasing temp will shift position of equilibrium to left system tries to decease temp to reach equilibrium yield of products falls. Solution turns brown.
Endothermic:
Decreasing the tempreture causes equilibrium position to shift to the left or reverse reaction to increase temp or yield of products
Increasing temp causes equilibrium position to shift to the left to decrease temp and yield of the products Solution turns yellow.
How does adding at a catalyst change the position of equilibrium?
Using catalyst doesn’t shift position of equilibrium. It does increase Rate of Reaction by lowering Activation energy increase in the forward and Reverse reaction so that equilibrium is reached faster.
What is the Haber process?
Haber process important industrial process. Produces ammonia (NH3) used in industrial processes like production of fertiliser
Combines nitrogen from the air with hydrogen derived from natural gas into ammonia. Reaction is reversible and forward reaction is exothermic.
What is the atom economy for this reaction and why is the yield never 100%
Atom economy in this reaction is 100% as there is only one product.
The yield is never 100% as the reaction is reversible. It is important to carry out at optimal conditions in industry to get efficent yield.
Why is High pressure and Low tempreture favoured in aforward reaction?
This is a forward reaction
High pressure 4 moles of reacts 2 moles of products equilibrium shift to decrease pressure shift to side with fewest moles so shifts to right.
Low Tempreture forward reaction is exothermic as the temp is decreased equilibrium will shift to increase the temp equilibrium will shift right.
What are the conditions for this reaction?
Iron catalyst
Pressure = 200 atmospheres
Tempreture = 450c
Gases are cooled and liquid ammonia is removed
Unreacted hydrogen and nitrogen are recycled back into the reaction vessel.
Why is there a high tempreture and high pressure for this reaction?
Low tempreture produces a high yield of ammonia but the rate of reaction is too slow. A compromised tempreture of 450C is used as it produced ammonia at a reasonable rate.
A high pressure will produce a high yield of ammonia but high pressures require expensive equipment and therefore there is a slightly compromised pressure of 200
What effect does the removal of ammonia have on the equilibrium position?
Equilibrium shift to increase (NH3) so shifts to the right
What effect does recycling hydrogen and nitrogen have on equilibrium position?
Equilibrium will decrease by shifting to left.
Why is iron catalyst used in this reaction
To speed up the rate of reaction.
