c6 - the rate and extent of chemical change Flashcards
how can the rate of a chemical reaction be found
measuring the quantity of a reactant used or the quantity of product formed over time
mean rate of reaction =
quantity of reactant used / time taken
quantity of product formed / time taken
how can the quantity of reactant or product be measured
mass in grams or by volume in cm3.
what factors affect the rates of chemical reactions
The concentrations of reactants in solution
The pressure of reacting gases
The surface area of solid reactants
The temperature
The presence of a catalyst
what is collision theory
chemical reactions can occur only when reacting particles collide with each other
and with sufficient energy
what is activation energy
the minimum amount of energy that particles must have to react.
how does increasing the concentration effect the rate of reaction
increases the frequency of collisions, and so increases the rate of reaction.
how does increasing the pressure effect the rate of reaction
increases the frequency of collisions, and so increases the rate of reaction.
how does increasing the surface area effect the rate of reaction
increases the frequency of collisions, and so increases the rate of reaction.
how does increasing the temperature effect the rate of reaction
increases the frequency of collisions and makes the collisions more energetic, and so increases the rate of reaction.
what is a catalyst
Substance which increase the rate of reaction but are not used up during the reaction.
what does a catalyst do
provides a different pathway for the reaction that has a lower activation energy.
What is meant by a reversible reaction
The products of a reaction can react to produce the original reactants.
If a reaction is endothermic in one direction, what is it in the other direction
Exothermic.
What is meant by the term equilibrium
Forward and reverse reactions occur at the same rate.
