Gr12 Energy, reaction rate and equilibirium Flashcards
Define heat of reaction
It is the energy absorbed or released in a chemical reaction.
Define exothermic reactions
Reactions that release energy.
Define endothermic reactions
It is reactions that absorb energy.
Define activation energy
It is the minimum energy needed for a reaction to take place.
Define an activated complex
It is the unstable transition state from reactants to
products.
Define reaction rate
It is the change in concentration of reactants or products per unit
time.
List the factors that affect the rate of chemical reactions
nature of reacting substances,
surface area,
concentration (pressure for gases),
temperature
and the presence of a catalyst.
Define the term positive catalyst
It is a substance that increases the rate of a chemical
reaction without itself undergoing a permanent change.
Explain Open system in chemistry
A system which continuously interacts with the environment –
it exchanges matter and energy with its environment.
Explain Closed system
A system that only exchanges energy with its surroundings, but it does not exchange matter with its surroundings.
Define A reversible reaction
A reaction is reversible when products can be converted back to reactants.
Define Chemical equilibrium
It is a dynamic equilibrium when the rate of the forward reaction equals the rate of the reverse reaction.
List the factors that influence the position of an equilibrium
pressure (gases only),
concentration
and temperature.
State Le Chatelier’s principle
When the equilibrium in a closed system is disturbed,
the system will re-instate a new equilibrium by favouring the reaction that will oppose the disturbance.
