Rates of Reaction Flashcards
What are rates of reaction?
the speed at which the amount of reactants decreases or the amount of products increases.
What is the formula for rate of reaction?
(change in concentration,volume,mass)/time
What is wrong about the formula?
it is the mean rate of reaction throughout the full reaction, in reality is starts fast and slows down
What is the collision theory?
for particles to react, they have to collide with each other with sufficient activation energy. if there isn’t enough the reaction cannot occur and the particles just move apart without reacting.
What are the 2 things that are affected by the factors affecting rates of reaction?
- the amount of energy the particles have
the more energy they can transfer during the reaction the more likely they can surpass the minimum activation energy. meaning number of successful collisions increases - frequency of collisions
particles gain kinetic energy, move faster and collide more frequently. if the collisions occur more frequently the chances for successful collisions increases
What are the factors affecting rates of reaction?
temperature, pressure, concentration, surface area, catalyst
How does temperature affect the rate of reaction?
as the temperature incresaes, particles gain kinetic energy and therefore move faster. So the frequency of collisions increases as well with more energy. This means that these particles are more likely to exceed the minimum activation energy and there will be a higher rate of successful collisions, leading to a higher rate of reaction according to collision theory.
How does concentration and pressure affect the rate of reaction?
increasing the concentration/pressure increases the particles per unit volume, this increases the frequency of collisions therefore increasing the rate of reaction
What does concentration/pressure refer to in rates of reaction?
how many particles there are per unit volume
concentration: solutions
pressure: gases
How does surface area affect the rate of reaction?
higher surface area means more particles are exposed to collide with eachother. eg a powder instead of small chunks. although same volume, powder can have a higher frequency of collisions. increasing the rate of reaction.
How does a catalyst affect the rate of reaction?
catalyst: substances that speed up reactions without being used up and remain chemically unchanged at the end of the reaction
they lower the activation energy by providing an alternative reaction pathway. therefore theres a higher frequency of successful collisions and the rate of reaction increases.
