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
True or false: catalysts don’t affect the position of equilibrium in a reversible reaction
True
What is the definition of a catalyst
A substance that affects the rate of chemical reactions without being changed up or used in the process.
The curve on the Maxwell-Boltzmann distribution never touches the X axis. What does this tell us about particle energy?
No particles have 0 energy
Why does temperature increase the rate of reaction
Particles have mor
Which distribution compared the fraction of particles with the amount of energy they have?
The Maxwell Boltzmann distribution
How does increasing concentration increase the rate of reaction?
More particles mean a higher chance of a collision, which gives a higher chance of the particles reacting
Which type of reaction results in the reactants having less energy than the products?
Endothermic
How do catalasts lower the activation energy needed for a reaction
They provide a different pathway (that requires less energy)
True or false: catalysts affect the enthalpy change of a reaction
False
Do catalysts affect the position of equilibrium in reversible reactions?
No
What is the definition of a catalyst?
A substance which affects the rate of a chemical reaction without being changed or used up in the process
The curve on the Maxwell Boltzmann Distribution never touches the X axis. What does this tell us?
No particles have 0 energy
Why does the increase of temperature affect reaction rate?
The particles have more kinetic energy, so move fast which gives a higher chance of successful collisions
Raising temperature by 10 degrees Celsius does what to the reaction rate? (Approximately)
Doubles rate of reaction
