Equilibrium Flashcards
When is a chemical reaction in equilibrium
A chemical reaction is in equilibrium when the composition of the reactants and products remains constant indefinitely.
What does the letter K represent and say
The equilibrium constant ( K ) characterises the equilibrium composition of the reaction mixture.
Whats the general equation for K
For the general reaction aA + bB ~cC +dD expression is:
K=[C]^c.[D]^d/[A]^a.[B]^b
The value of equilibrium constant can be … and indicates and have no
The value of equilibrium constants can be calculated.
The value of an equilibrium constant indicates the position of equilibrium.
Equilibrium constants have no units.
Describe factors that affect and don’t affect the equilibrium constant
The numerical value of the equilibrium constant depends on the reaction temperature and is independent of concentration and/or pressure.
Describe an endothermic reactions yield of product when temperature increases and its affect on k
For endothermic reactions, a rise in temperature causes an increase in K and the yield of the product is increased.
Describe the affect of increasing temperature in a exothermic reaction and the change in value k
For exothermic reactions, a rise in temperature causes a decrease in K andtheyieldoftheproductisdecreased.
How does a catalyst affect the equilibrium constant
The presence of a catalyst does not affect the value of the equilibrium constant.
Describe the equilibrium between water and hydroxide ions and when it occurs
In water and aqueous solutions there is an equilibrium between the water molecules and hydronium (hydrogen) and hydroxide ions.
This ionisation of water can be represented by: H2O( ) + H2O(l ) H3O+ (aq) + OH− (aq)
What does H3O+ represent
H3O+ (aq) represents a hydronium ion, a hydrated proton. A shorthand representation of H3O+ (aq) is H+ (aq) .
What is name given to water which can act as a base and acid
Water is amphoteric (can react as an acid and a base).
What is the dissociation constant for the ionisation of water
The dissociation constant for the ionisation of water is known as the
ionic product and is represented by K w : K =[H3O+][OH–]
What does the ionic product vary with
The value of the ionic product varies with temperature.
What what temperature is the Kw at 1x10^-14
At 25°C the value of K w is approximately 1 × 10-14
What is the relationship between pH and the hydrogen ion concentration
The relationship between pH and the hydrogen ion concentration is given by:
pH=−logbase10 [H3O+] and [H3O+] =10−pH
