1.5 Kinetics Flashcards
5 Variables that affect the rate of reaction
Temperature, Concentration, Surface area, Pressure, Presence of a catalyst
Definition of activation energy
The minimum energy particles must collide with in order to react
Definition of rate of reaction
The amount of product formed/ amount of reactant used up in a given time
Why do most collisions of particles not result in a reaction?
In order for molecules to react, the colliding molecules must have enough kinetic energy to overcome the repulsive and bonding forces in the reactants or the collisions are not in the right orientation
What effect does increasing the temperature have on the rate of reaction?
The particles have more kinetic energy so move about faster, so there are more frequent collisions, with enough activation energy to react so the rate of reaction is faster
What does increasing the concentration have on the rate of reaction?
There are more particles in the same volume so there are more frequent collisions and the reaction happens faster
What effect does decreasing the pressure in a gaseous reaction have on the rate of reaction?
It’s reduces the rate of reaction as there are less molecules in a given volume so there are less frequent collisions
The effect of increasing the surface area on the rate of reaction
Increasing the surface area means that there are more sites for the reaction to take place so the reaction happens faster
Why a small temperature increase can lead to a large increase in rate of reaction (in terms of Maxwell-Boltzmann distribution)
A higher temperature means more of the molecules have energy greater than Activation energy so a higher percentage of collisions will result in a reaction occurring
The effect of a catalyst on the rate of reaction
It decreases the activation energy as it provides an alternate route for the reaction to occur and so the rate of reaction is increased
Which distribution compares the fraction of particles and the amount of energy that they have?
The Maxwell Boltzmann Distribution
How does increasing concentration of a solution increase the rate of a chemical reaction?
There are more particles in the solution, therefore there is a higher chance of successful collisions
Which type of reaction leads to the products have more energy than the starting reactants?
Endothermic reactions
How do catalysts lower the activation energy for a reaction?
Provide a different pathway that requires less energy
True or false: catalysts affect the enthalpy change of reactions.
False - catalysts do not affect enthalpy change
