Chapter 5 - Rates of Reactions Flashcards
What are the two fundamental things needed for particles to react?
- have the correct orientation
- Sufficient amount of energy (above Ea)
What is Activation Energy (Ea)?
The amount of energy needed to break the original bonds in a molecule so a chemical reaction can occur.
What can we measure to see if a chemical reaction has taken place?
- vol of gas evolved
- decrease of mass due to gas evolving
- mass of solid formed
- intensity of colour in solution
- formation of a precipitate
- pH change
- temperature change
What does a maxwell-boltzmann curve show?
These distribution curves represent the kinetic energy of the molecules in a substance.
The highest point is the most probable velocity. This is not the same a s average velocity.
Area under graph represents no. of particles
What temperature increase do to maxwell-boltamann curve?
Stretches it to the right, highest point comes down and moves to the right, larger area past Ea
What does a catalyst do to a maxwell-boltmann curve?
Moves the vertical line representing Ea to the left so that there is more area past the Ea
what are ways to increase rate of reaction?
- increasing pressure
- increasing temp
- increasing surface area
- adding catalyst
How does pressure increase rate?
Higher pressure pushes molecules closer together therefore can come into contact more frequently therefore increase number of successful collisions
How does temperature increase rate?
higher temp=more kinetic energy=more collisions with sufficient energy=more successful collisions
How does Surface area increase rate?
increasing SA=more places for reactants to come into contact=more successful collisions
What is the function of a catalyst?
To provide an alternate reaction pathway, with a lower activation energy, for a reaction to occur at a faster rate.
