Cambridge International AS and A Level Chemistry (9701)
University of Indonesia CHEM 004
Summary & 15’s Chemical Equilibria Practice Exam Solutions
Chemical Equilibria
, Equilibrium Concept
IRREVERSIBLE REACTION REVERSIBLE REACTION
An irreversible reaction is a reaction A reversible reaction is a reaction
that takes place in the same that goes in both directions (back
direction or a reaction that cannot and forth). In this case the product
reversed. can react again to form reactants.
CH4(g) + 2 O2(g) CO2(g) + 2 H2O(g) N2(g) + 3 H2(g) 2 NH3(g)
The reaction to the right is called
the forward reaction, the reaction
to the left is called the reverse
reaction
Equilibrium State
Concentration (M) Characteristic of equilibrium
Equilibrium time is obtained
when the rate of the forward
reaction = the rate of the
reverse reaction
Although in a state of
equilibrium the
concentrations of the
reactants and products
remain constant,
The reaction continues at the
molecular level, so this
equilibrium is called a
Equilibrium Time
Dynamic Equilibrium.
It requires a closed system
, Equilibrium Type
HOMOGENEOUS EQUILIBRIUM HETEROGENEOUS EQUILIBRIUM
Homogeneous Equilibrium: Heterogeneous Equilibrium:
Equilibrium in which all the Equilibrium consisting of two or
components are in one phase. more phases.
N2(g) + 3 H2(g) 2 NH3(g) CaCO3(s) CaO(s) + CO2(g)
CH3COOH(aq) CH3COO-(aq) + H+(aq) Ag2CrO4(s) 2 Ag+(aq) + CrO42-(aq)
Laws and Provisions of Equilibrium
The product of the equilibrium concentrations of a substance on the right
side divided by the product of the equilibrium concentrations of a substance
on the left side, each raised to the power of its reaction coefficient, has a
certain value at a certain temperature.
aA + bB cC + dD
Concentration Equilibrium Pressure Equilibrium Constant
Constant (Kc) (Kp)
Aqueous (aq) and gas (g) gas (g)
Solid (s) and liquid (l) solid (s), liquid (l), aqueous
(aq)
Kp = Kc (RT)n The partial pressure of each gas is
proportional to the moles in the
R = ideal gas constant balanced state.
T = absolute temperature The total pressure of the gases is
the sum of the partial pressures
n = the number of product of all the gases
coefficients minus the number
of reactant coefficients
University of Indonesia CHEM 004
Summary & 15’s Chemical Equilibria Practice Exam Solutions
Chemical Equilibria
, Equilibrium Concept
IRREVERSIBLE REACTION REVERSIBLE REACTION
An irreversible reaction is a reaction A reversible reaction is a reaction
that takes place in the same that goes in both directions (back
direction or a reaction that cannot and forth). In this case the product
reversed. can react again to form reactants.
CH4(g) + 2 O2(g) CO2(g) + 2 H2O(g) N2(g) + 3 H2(g) 2 NH3(g)
The reaction to the right is called
the forward reaction, the reaction
to the left is called the reverse
reaction
Equilibrium State
Concentration (M) Characteristic of equilibrium
Equilibrium time is obtained
when the rate of the forward
reaction = the rate of the
reverse reaction
Although in a state of
equilibrium the
concentrations of the
reactants and products
remain constant,
The reaction continues at the
molecular level, so this
equilibrium is called a
Equilibrium Time
Dynamic Equilibrium.
It requires a closed system
, Equilibrium Type
HOMOGENEOUS EQUILIBRIUM HETEROGENEOUS EQUILIBRIUM
Homogeneous Equilibrium: Heterogeneous Equilibrium:
Equilibrium in which all the Equilibrium consisting of two or
components are in one phase. more phases.
N2(g) + 3 H2(g) 2 NH3(g) CaCO3(s) CaO(s) + CO2(g)
CH3COOH(aq) CH3COO-(aq) + H+(aq) Ag2CrO4(s) 2 Ag+(aq) + CrO42-(aq)
Laws and Provisions of Equilibrium
The product of the equilibrium concentrations of a substance on the right
side divided by the product of the equilibrium concentrations of a substance
on the left side, each raised to the power of its reaction coefficient, has a
certain value at a certain temperature.
aA + bB cC + dD
Concentration Equilibrium Pressure Equilibrium Constant
Constant (Kc) (Kp)
Aqueous (aq) and gas (g) gas (g)
Solid (s) and liquid (l) solid (s), liquid (l), aqueous
(aq)
Kp = Kc (RT)n The partial pressure of each gas is
proportional to the moles in the
R = ideal gas constant balanced state.
T = absolute temperature The total pressure of the gases is
the sum of the partial pressures
n = the number of product of all the gases
coefficients minus the number
of reactant coefficients
