The Rate and Extent of Chemical Change Flashcards
What is the formula to calculate the rate of reaction?
RofR = amount of reactant used (or product formed) divided by time taken
How do you calculate the rate of reactions graphically?
Draw a tangent on the curved line and then calculate the gradient of the tangent.
Describe how concentration affects the rate of reaction?
If the concentration is increased, there will be more particles present, so more successful collisions, so RofR is increased
Describe how temperature affects the rate of reaction?
By increasing the temp, particles can collide more often with more energy, meaning RofR increases.
Describe how surface area affects the rate of reaction?
If the SA is increased, more particles are exposed to the reactant, so more collisions, so RofR increases.
Describe how pressure affects the rate of reaction?
By increasing the pressure, there are more particles for a given volume, so more collisions, meaning the RofR increases.
Describe how catalysts affect the rate of reaction?
Catalysts speed up the reaction without being changed or used up. It does this by providing a different pathway with a lower activation energy. Enzymes are an example of a biological catalyst.
What is collision theory?
Collision theory states that reactions can only happen if particles collide with enough energy to change into a new substance. the minimum amount of energy needed is called the activation energy.
What is equilibrium in a reversible reaction?
When a reversible reaction occurs in a closed system, equilibrium is reached when the reactions occur at exactly the same rate in each direction.
What is the effect of changing conditions on equilibrium (Le Chatelier’s principle)?
If a system is at equilibrium and changes are made to the conditions, then the system responds to counteract the change.
Describe the effect on the equilibrium of changing concentration within a reaction
Concentration of reactants increased = equilibrium shifts towards the products
Concentration of products increased = equilibrium shifts towards the reactants
Describe the effect on the equilibrium of changing the temperature within a reaction
Temp increased = equilibrium shifts towards endothermic reaction
Temp decreased = equilibrium shifts towards exothermic reaction
Describe the effect on the equilibrium of changing the pressure within a reaction
Pressure increased = equilibrium shifts towards side with fewer moles
Pressure decreased = equilibrium shifts towards side with more moles
