Kinetics basics Flashcards
Rate of reaction
Change in concentration of reactants or products per unit time
Units: mol dm3 s1
How to find instantenous rate of reaction on a concentration vs time graph
Draw tangent to graph at that point in time. Find gradient of tangent
Activation energy
Minimum energy that reacting particles need for a successful reaction to start
According to collision theory, what 3 things are needed for a chemical reaction to occur?
- Particles must physically collide with each other
- Colliding particles must have the correct mutual orientations
- Reacting particles must have sufficient kinetic energy to initiate reaction
How does an increase in temperature increase rate of reaction?
Particles gain more kinetic energy, move faster and collide more frequently.
More particles have an energy equal to or greater than activation energy, so more successful collisions.
How does an increase in temperature increase rate of reaction?
Particles gain more kinetic energy, move faster and collide more frequently.
More particles have an energy equal to or greater than activation energy, so more successful collisions.
What is a catalyst?
A substance that increases the rate of a chemical reaction but is not used up in the reaction and remains chemically unchanged
How does a catalyst increase rate of reaction?
It lowers the activation energy
How does a catalyst increase rate of reaction?
It lowers the activation energy
How does increasing concentration increase rate of reaction?
There will be more reactant particles in the same fixed volume, increasing the number of successful collisions
How does increasing surface area(by decreasing particle size) increase rate of reaction?
More surfaces are exposed, leading to more successful collisions.
How does increasing pressure increase rate of reaction?
If 1 or more reactants are gases, increasing pressure forces particles closer together. This increases the collision rate and the number of successful collisions
Homogenous catalyst
It is in the same physical state as the reactants
Heterogenous catalyst
It is in a difficult physical state (usually solid) from the reactants (which may be liquids or gases)
How does a heterogenous catalyst work?
It provides a surface that correctly orientates reactant molecules and makes collisions more successful
