Unit 3 Equilibrium, Acids and Redox Reactions
Topic 1 – Chemical Equilibrium concept map
1.1 Chemical Equilibrium Equilibrium graphs
Open vs Closed Systems Rate vs time
Open system: Both matter and energy can be exchanged from the system (reaction) to the surrounding. Concentration vs Time
Closed: Matter is not exchanged but energy can be exchanged from the system to the surrounding. Key features to look at
Key Features of Dynamic Equilibrium (5) 1. Sudden spikes
2. Gradual increases or decreases.
1. The rate of the forward and reverse reaction is equal. 3. Ratio of increases/decrease. If 1:2 ratio
2. The concentration of products and reactants do not change. Are not equal concentrations as there are mole ratios to consider. (reactants: products). Reactants increase
3. Observable properties such as change in colour at constant temperature. but products increase double the
4. Catalyst will increase rates of reactions, but equilibrium position of the system will not change. amount.
5. Temperature, pressure (for gases only) and change in concentrations are factors that effect the equilibrium position. 4. Flat lines mean reaction is at equilibrium.
1.2 Factors that Affect Equilibrium
Le Chatelier’s Principle: States that when a system is in state of dynamic equilibrium and is subjected to a change, it will adjust itself to partially oppose the effect.
Temperature: Pressure: Concentration:
Exothermic: increasing temp shifts position to the left and Increasing pressure will favour the side Adding a reactant will increase the rate of the net forward reaction and the
decreasing temp will shift it to the right. with the least number of particles. In this equilibrium position will shift to the right to oppose the excess reactant,
case the reactants and products ratio is resulting to an increase in products.
Endothermic: increasing temp shifts it to the right and 4:2. This means the products side will be
decreasing temp will shift it the left. Adding a product, shifts to the left and rate of the net reverse reaction
favoured if pressure increases. On the
increases to consume the excess products.
Will be explained more in 1.3 section. other hand, if pressure decreases the side
with the greater number of particles will Explanation continued in next page.
From the graph, at t =3 there is change in temperature. be favoured, the reactants.
Changes in temperature takes time hence there are only
gradual changes. Steps to analyse temp graph: At t=2 there are two sudden spikes and
a curved increase. Usually these are the
1. Determine the type of reaction. In this case we have signs it is a change in pressure. If there is
an exothermic as enthalpy is negative only one reactant and one product, then
2. What is increasing/decreasing? N 2 and H 2 are it would be one sudden spike and a
gradually increasing while N H 3 is gradually curved increase/decrease. As the sudden
decreasing. This means there is a net reverse spikes then decrease for the reactants,
reaction as more products are getting produced. the products are favoured. The products
Hence there is an increase in temperature as the net have a smaller number of particles thus
reverse reaction (endothermic reaction) is favoured. this means the pressure have increased.
Topic 1 – Chemical Equilibrium concept map
1.1 Chemical Equilibrium Equilibrium graphs
Open vs Closed Systems Rate vs time
Open system: Both matter and energy can be exchanged from the system (reaction) to the surrounding. Concentration vs Time
Closed: Matter is not exchanged but energy can be exchanged from the system to the surrounding. Key features to look at
Key Features of Dynamic Equilibrium (5) 1. Sudden spikes
2. Gradual increases or decreases.
1. The rate of the forward and reverse reaction is equal. 3. Ratio of increases/decrease. If 1:2 ratio
2. The concentration of products and reactants do not change. Are not equal concentrations as there are mole ratios to consider. (reactants: products). Reactants increase
3. Observable properties such as change in colour at constant temperature. but products increase double the
4. Catalyst will increase rates of reactions, but equilibrium position of the system will not change. amount.
5. Temperature, pressure (for gases only) and change in concentrations are factors that effect the equilibrium position. 4. Flat lines mean reaction is at equilibrium.
1.2 Factors that Affect Equilibrium
Le Chatelier’s Principle: States that when a system is in state of dynamic equilibrium and is subjected to a change, it will adjust itself to partially oppose the effect.
Temperature: Pressure: Concentration:
Exothermic: increasing temp shifts position to the left and Increasing pressure will favour the side Adding a reactant will increase the rate of the net forward reaction and the
decreasing temp will shift it to the right. with the least number of particles. In this equilibrium position will shift to the right to oppose the excess reactant,
case the reactants and products ratio is resulting to an increase in products.
Endothermic: increasing temp shifts it to the right and 4:2. This means the products side will be
decreasing temp will shift it the left. Adding a product, shifts to the left and rate of the net reverse reaction
favoured if pressure increases. On the
increases to consume the excess products.
Will be explained more in 1.3 section. other hand, if pressure decreases the side
with the greater number of particles will Explanation continued in next page.
From the graph, at t =3 there is change in temperature. be favoured, the reactants.
Changes in temperature takes time hence there are only
gradual changes. Steps to analyse temp graph: At t=2 there are two sudden spikes and
a curved increase. Usually these are the
1. Determine the type of reaction. In this case we have signs it is a change in pressure. If there is
an exothermic as enthalpy is negative only one reactant and one product, then
2. What is increasing/decreasing? N 2 and H 2 are it would be one sudden spike and a
gradually increasing while N H 3 is gradually curved increase/decrease. As the sudden
decreasing. This means there is a net reverse spikes then decrease for the reactants,
reaction as more products are getting produced. the products are favoured. The products
Hence there is an increase in temperature as the net have a smaller number of particles thus
reverse reaction (endothermic reaction) is favoured. this means the pressure have increased.
