Physical Chemistry Flashcards
(29 cards)
When is a chemical reaction in equilibrium?
When the composition of the reactants and products remains constant indefinitely.
What is the equilibrium constant?
K
What does the numerical value of the equilibrium constant depend on?
It depends on the reaction temperature and is independent of concentration and pressure.
What does the value of equilibrium constant indicate?
The position of equilibrium.
What are the concentrations of pure solids and pure liquids at equilibrium taken as?
They are taken as constant and given a value of 1 in the equilibrium expression.
What happens to the equilibrium constant in an endothermic reaction?
A rise in temperature causes an increase in K and the yield of product is increased.
What happens to the equilibrium constant in an exothermic reaction?
A rise in temperature causes a decrease in K and the yield of product is decreased.
Does the presence of a catalyst affect the value of the equilibrium constant?
No
In water and aqueous solutions what is there an equilibrium between?
Between the water molecules and hydronium (hydrogen) and hydroxide ions.
How can the ionisation of water be represented?
H2O (l) + H2O (l) <=> H3O^+ (aq) + OH^- (aq)
What does H3O^+ (aq) represent?
A hydronium ion which is a hydrated proton.
What is a shorthand representation of H3O^+ (aq)?
H^+ (aq)
What does amphoteric mean?
It means it can react as an acid or as a base.
Is water amphoteric?
Yes.
What is the dissociation constant for the ionisation of water known as?
Known as the ionic product.
What does the Brønsted-Lowry definition state?
States that an acid is a proton donor and a base is a proton acceptor.
For every acid there is a conjugate base, what is this formed by?
Formed by the loss of a proton.
For every base there is a conjugate acid, what is this formed by?
Formed by the gain of a proton.
What are strong acids and bases in aqueous solutions?
They are completely dissociated into ions.
What are weak acids and bases in aqueous solutions?
They are partially dissociated into ions.
What are some examples of strong acids?
Hydrochloric acid, sulfuric acid and nitric acid.
What are some examples of weak acids?
Ethanoic acid, carbonic acid and sulfurous acid.
What are solutions of metal hydroxides?
Strong bases.
What is ammonia and amines examples of?
Weak bases.
