Ch - 9 (Reversible Reactions) Flashcards
What happens in a reversible reaction?
Reaction can go in both directions.
To the right (forms the products)
To the left (forms the reactants)
What does the Haber process help in the production of?
Ammonia, hydrogen and nitrogen
What colour do anhydrous blue cobalt (II) chloride crystals turn into when water is added.
pink
What colour do cobalt crystals turn into when heated?
Blue (water of crystallisation is lost)
What are the chemical tests commonly used to detect the presence of water?
CoCl2 (Copper chloride)
CuSO4 (Copper sulfate)
What happens in the concept of equilibrium?
The rate of forward reaction equals the rate of the reverse reaction.
How is the molecules affecting the concept of equilibrium?
Dynamic, molecules are changing into each other by chemical reactions constantly changing
What happens to the concentration in equilibrium?
Remains constant in a closed system
What happens to the position of equilibrium when concentration of reactant increases?
Shifts to the left
What happens to the position of equilibrium when concentration of product increases?
Shifts to the right
What does the Le Chatelier principle state?
When a change is made to the conditions of a system at equilibrium, the system automatically moves to oppose the change.
What is the Le Chatelier Principle used to predict?
Predicts the chances to the position of equilibrium when there ate changes in temperature, pressure and concentration.
What is the effect on equilibrium when temperature is increased?
Moves in the endothermic direction to reverse the change.
What is the effect on equilibrium when temperature is decreased?
Equilibrium moves in the exothermic direction to reverse the change.
What is the effect of an increase in pressure on equilibrium?
shifts in the direction that produces the smaller number of molecules of gas to decrease the pressure again.
What is the effect of an decrease in pressure on equilibrium?
equilibrium shifts in the direction that produces large number of molecules of gas to increase the pressure.
What is the effect of an increase in concentration on Equilibrium?
Shifts to the right to reduce the effcf of increase in conc. of a reactant
What is the effect of a decrease in concentration on Equilibrium?
equilibrium shifts to the left to reduce the effect of a decrease in reactant
What is the effect of a catalyst on Equilibrium?
it does not affect the position of equilibrium but it does increase the rate at which equilibrium is reached.
Why does a catalyst not have an effect on equilibrium?
- Catalyst increases the rate of both forward and backward reactions by the same amount.
- Concentration of reactant and products is the same.
Define Haber process.
The manufacturing of ammonia in an exothermic reaction.
What are the stages of Haber process?
Stage 1: H2 and N2 are obtained from natural gas and the air respectively and are pumped into the compressor through pipe.
Stage 2: Gasses are compressed to about 200 atmospheres inside the compressor.
Stage 3: Pressurized gases are pumped into a tank
Stage 4: Unreacted H2 & N2 and the product ammonia pass through the cooling tank. The ammonia is liquefied and removed to pressurize storage vessels.
Stage 5: The unreacted H2 and N2 gases are recycles back into the system and it starts over again.
What happens to yield as pressure increases on x - axis ?
Yield increases at any temperature.
What happens to yield as temperatures decreases on y - axis ?
the yield increases
What’s re the economic conditions in the Haber peocess?
- Readily available and inexpensive to purify
- Nitrogen: From the air
- Hydrogen: From natural gas
What are the conditions needed for Haber process?
a) Temperature
b) Pressure
c) catalyst
a) Temperature - 450°C
b) Pressure - 200atm
c) catalyst - iron
What will happen at a higher temperature for Haber process?
- Favour the reverse reaction as it is endothermic (takes in heat) so a higher yield of reactants would be made.
What will happen at a lower temperature for Haber process?
It favors the forward reaction as it is exothermic (releases heat) so a higher yield of products would be made.
What will happen at Lower pressure for the Haber process?
- Favor the reverse reaction, the system will try to increase the pressure by creating more molecules, so a higher yield of reactant will be made
What will happen at higher pressure for the Haber process?
Favor the forward reaction as it will try to decrease the pressure by creating less molecules, so a higher yield of products will be made.
What will happen for catalyst iron in Haber process?
It allows an acceptable yield to be achieved at a lower temperature by lowering the activation energy required
What is a contact process?
- sulfuric acid synthesized by the contact process.
- concentrated sulfuric acid is used in car batteries, making fertilizers, soaps and detergents
What are the stages of contact process?
Stage 1: Production of sulfur dioxide, with by burning sulfur to oxidise the sulfur, or roasting sulfide ores.
Stage 2: the oxidation of sulfur dioxide to sulfur trioxide using vanadium (V) oxide, V2O5, catalyst.
O2 is obtained from the air.
What are the conditions needed for Haber process?
a) Temperature
b) Pressure
c) catalyst
a) Temperature - 450°C
b) Pressure - 200kPa
c) catalyst - vanadium (V) oxide
Why is increasing the temperature Good in contact process?
- Forward reaction is exothermic, it shifts the equilibrium to the left of the reactants
- higher temperature, lowers the yield of sulfur trioxide
Why is increasing the pressure in contact process Good?
- Shifts the equilibrium to the right, in direction of a smaller no. molecules
- equilibrium lies far to the right
Why the contact process carried just above atmospheric pressure?
- High pressures can be dangerous and very expensive equipment is needed
- A higher pressure causes the sulfur dioxide to liquefy
