Flashcards in Rate & Extent of Chemical Change Deck (18):
What are the two equations for mean rate of reaction?
Mean Rate of Reaction= Quantity of used Reactant/Time
Mean Rate of Reaction= Quantity of Product/Time
What is the unit for rate of reactions?
g/s, mol/s or cm³/s
As product or reactant can be measured in mass or volume or moles.
Which factors affect the rate of reactions?
Concentration(solution), Pressure(g), Surface Area(s), temperature and catalysts.
What is collision theory?
The theory explaining how chemical reactions occur.
How do chemical reactions occur?
When two reacting particles collide with each other with sufficient energy to react. This energy is the activation energy.
What is the activation energy?
The minimum energy for particles to collide and react.
How does concentration, pressure and surface area increase the rate of reaction?
This increases the frequency of collisions and thus the rate of reaction is increased due to the increased number.
How does increasing the temperature increase the rate of reaction?
The particles collide more frequently as the particles move further. The collisions are also more energetic and thus a greater number of sufficiently energised collisions occur.
Why is surface area to volume ratio important?
An object with a greater surface area to volume ratio will react completely faster.
What are catalysts?
Particles which change the rate of reaction but are not used up.
What are biological catalysts?
How do catalysts function?
They provide a pathway of reduced activation energy to increase the rate of reaction.
What is a reversible reaction?
A chemical reactions in which the products can to react to form the reactants.
How can some reactions be reversed?
Changing conditions (heat for example) the energy released and absorbed is equal in both reactions.
What is it when reversible reactions reach equilibrium?
When, in closed apparatus- where products cannot escape, the rate of reaction for forward and reverse reactions occur at the same rate- they are equal.
How does concentration in a system affect the equilibrium?
Reactants or products will react in inverse to the concentration to find an equilibrium with the same number of moles in each solution.
How does temperature in a system affect the equilibrium?
If temperature increases:
Endothermic products increase
Exothermic products decrease