Reaction Kinetics Flashcards
What is the activation energy?
The minimum energy needed for a reaction to occur.
What is a catalyst?
A substance that speeds up a chemical reaction but is chemically unchanged at the end. They work by providing an alternate reaction pathway with a lower activation energy.
What is enthalpy change?
A heat change at a constant pressure
Define rate of reaction
Change in the concentration of a reactant or product per unit time.
What 3 things must occur for a chemical reaction to occur?
- Reacting particles
- Correct orientation
- Sufficient amount of energy
What is the collision frequency?
The number of collisions per unit time
What happens in an exothermic reaction?
The reactants are higher in energy than the products. The enthalpy of the reacting system decreases and the enthalpy change is negative. Energy is transferred from the reacting system to the surroundings.
What happens in an endothermic reaction?
The reactants are lower in energy than the products. The enthalpy of the reacting system increases so the enthalpy change is positive. Energy is transferred to the reacting system from the surroundings.
How does increasing the temperature affect the rate of reaction?
Increase in temp increases ke of particles
This increases the frequency of collisions and a greater proportion of collisions will have the energy required to react. This gives more successful collisions.
How does increasing the concentration affect the rate of reaction?
Increase in concentration, more reactant particles present which leads to more successful collisions therefore increases rate of reaction.
How does increasing the pressure of the gas increase the rate of reaction?
Particles are forced closer together which leads to more successful collisions between reactants in a given time, increasing the rate of reaction.
How does using a catalyst affect the rate of reaction?
Provides an alternative pathway by lowering the activation energy, therefore more successful collisions in a given time so increases the rate of reaction.
How does using a catalyst affect the rate of reaction?
Provides an alternative pathway by lowering the activation energy, therefore more successful collisions in a given time so increases the rate of reaction.
