Rate of Reaction Flashcards
What factors affect the rate of reaction?
Changing concentration, particle size, or temperature
Instantaneous rate of a reaction is given by …
Instantaneous rate = 1/time
To increase rate of reaction how would you change concentration, temperature and particle size?
Concentration - Increase concentration
Temperature - Increase temperature
Particle Size - Decrease particle size to increase surface area of reactants.
What factors must be correct in order for a collision to result in a successful reaction?
Collision Geometry
Particles must have enough energy
How does increasing concentration and/or pressure increase rate?
When concentration or pressure is increased you have a greater number of particles in the same space, this increases the likelihood of collisions occurring and so increases rate of reaction due to greater number of collisions.
How does decreasing particle size increase rate?
Decreasing particle size increases surface area and so more surface is available for reactions.
Why does increasing temperature result in such a large increase in rate?
Increasing temperature increases the energy of all the particles, since temperature is a measure of the average KE of all the particles, so particles collide with higher energy and a larger number of particles have energy higher than the activation energy and so have sufficient energy to form an activated complex.
What affect does increasing the temperature have on a energy distribution diagram?
Shifts it to the right
In an exothermic reaction, the enthalpy change is… and why?
negative
Heat Energy has been released into the surroundings
In an endothermic reaction, the enthalpy change is … Why?
Positive
HEat Energy is absorbed from the surroundings, so products have more energy than reactants.
What is the activated complex?
A highly unstable arrangement of reactants and products formed at the intermediate stage of the reaction where old bonds are being broken and new bonds are being formed
How does a catalyst speed up the rate of reaction?
Form temporary bonds with reactants, which weakens the bonds, and so lowers the activation energy, providing an alternative, lower energy pathway for the reaction.
Where is the activated complex formed?
At the top of the reaction energy barrier?
