9. Equilibrium Flashcards
(16 cards)
What is a reversible reaction?
When the reacts react the form products, the products can react simultaneously to reform the reactants.
A reaction that goes in both forward and backward directions, represented by a double-facing arrow.
Define “equilibrium”.
The state achieved in a reversible reaction when the concentration of reactants and products remains constant.
Define “dynamic equilibrium”.
A reaction system in which the concentrations of the reactants and products remain constant (steady state) as the rates of the forward and reverse reactions are equal.
Define “homogenous system”.
All reactants and products are in the same physical state.
What is the position of equilibrium?
A measure, in a reversible reaction, of how far the reaction has proceeded to the right (towards the products) or remained to the left (towards the reactants).
To the left = little product, reactants predominate
To the right = little reactant remaining, products predominate
What are the factors affecting the position of equilibrium?
Concentration
Temperature
Pressure
Presence of a catalyst
How does concentration affect the position of equilibrium?
Increased reactant concentration ➡️ Increased product concentration ⬅ Decreased reactant concentration ⬅ Decreased product concentration ➡️ (Equilibrium shifts to the lower side, really)
How does temperature affect the position of equilibrium?
If forward reaction is endothermic: Increasing temperature ➡ Decreasing temperature ⬅️ If forward reaction is exothermic: Increasing temperature ⬅️ Decreasing temperature➡️
How does pressure affect the position of equilibrium?
Only applies in homogenous gaseous systems, and only if one side has fewer moles.
Increasing pressure favours the side with fewer moles so moves towards it.
Decreasing pressure favours the sides with more moles so moves towards it.
What is notable about high pressures in industry?
Expensive to apply.
Thick-walled vessels are required to contain it.
Safety issues - increased explosion risk.
What is the Haber process?
The industrial production of ammonia from nitrogen and hydrogen. Homogenous gaseous equilibrium. Exothermic.
How can position of equilibrium be affected in the Haber process?
Increasing temperature shifts equilibrium to the left, decreases yield.
Increasing pressure shifts equilibrium to the right, increases yield.
Iron catalyst speeds up attainment of equilibrium.
What are the conditions for the Haber process?
450 degrees Celsius (compromise temperature) 200 atm (high pressure to favour product yield) Iron catalyst (equilibrium attained more quickly)
What is the contact process?
The industrial production of concentrated sulfuric acid, wherein sulfur dioxide reacts with oxygen to form sulfur trioxide. Homogenous gaseous reaction. Exothermic.
How can position of equilibrium be affected?
Increasing temperature shifts left, lower product yield.
Increasing pressure shifts right, higher product yield.
Vanadium(v) oxide catalyst speeds up attainment of equilibrium.
What are the conditions for the contact process?
450 degrees Celsius (compromise temperature)
2 atm (to favour product yield)
Vanadium(v) oxide catalyst (quicker equilibrium attainment)
