Kinetics Flashcards
(17 cards)
Define activation energy.
The minimum amount of energy needed for a reaction to start.
What does the collision theory state?
For two particles to react they must collide with enough energy to break bonds in the correct orientation.
Is breaking bonds exothermic or endothermic?
endothermic
Is making bonds exothermic or endothermic?
exothermic
What is enthalpy change?
Energy change.
What are the factors that affect the rate of reaction?
The temperature
The pressure
The surface area of a solid
A catalyst
and the concentration of a substance
How does an increase in temperature affect the rate of reaction?
An increase in temperature means the particles have more kinetic energy and move randomly at higher speeds, which increases their frequency of successful collisions.
How does an increase in concentration affect the rate of reaction?
An increase in concentration means there are more reactant particles in a given volume, so there’s less free space, which increases the frequency of successful collisions.
How does an increase in pressure affect the rate of reaction?
An increase in pressure means particles are being compressed in a smaller volume so there is less free space, which increases their frequency of successful collisions.
How does an increase in surface area affect the rate of reaction?
An increase in surface area means there is more area for particles to collide with, which increases their frequency of successful collisions.
How does the addition of a catalyst affect the rate of reaction?
A catalyst provides an alternative reaction which overcomes the activation energy through the increased frequency of successful collisions.
Define the rate of reaction.
A change in concentration of reactant or product per unit of time.
What happens to the shape of the Maxwell-Boltzmann distribution graph when temperature increases?
The graph shifts to the right and lowers.
What happens to the shape of the Maxwell-Boltzmann distribution graph when the pressure in a gas increases and the concentration in a liquid increases?
The graph’s peak becomes larger and ends at a similar point.
Define catalyst.
A substance that affects the rate of a reaction but is chemically unchanged at the end of the reaction.
What is the use of catalytic converters?
They convert harmful pollutants from combustion into less harmful gases in a car.
Why are catalytic converters in a ‘honeycomb structure?
Catalytic converters are made of expensive metals such as rhodium, palladium, and platinum. This structure allows for the cost to be cheap and also have maximum successful collisions.
