Rates of reaction Flashcards
Define
effective collision
A collision which results in a reaction
that produces 1+ products
The speed of the reaction
state mathematical relationship
The speed of the reaction is directly proportional to the
- # collisions per unit time
- The fraction # collisions that are effective
When do reaction occur? When are collisions effective?
Reactions occur when reactant particles collide with
A. the correct orientation
B. sufficient energy
List 6 factors which affect the rate of reaction
- Temperature
- Concentration (liquids only)
- Surface area (solids only)
4, Pressure (gases only)
5, Catalysts
6, Nature of reactants
Define rate of reactionadn give unit
The change in concentration of reactants or products per unit time
mol.dm-3.s-1
Activation energy (or enthalpy Ea)
The (minimum) energy that a system must acquire before a chemical reaction can occur
reaction rate (mathematically) and unit
delta c
———– (change in conc. Pro. or Rea over time)
delta t
UNIT: mol.dm-3.s-1
Explain collision theory
- For a reaction to occur particles must collide
- This collision provides energy needed for reaction to take place
- A reaction can only occur if the collision is effective ( see conditions )
Activated complex
The unstable transition sate from reactants to products
Heat of the reaction
The energy absorbed or released in a chemical reaction.
Heat of the reaction linking to ΔH(Eb - Ef)
At constant pressure heat of reaction is referred to as enthalpy changes
Endothermic reactions
Reaction that absorb energy
ΔH>0
Exothermic reactions
Reactions that release energy
ΔH<0
Define collision theory
A model that explains reaction rate
-as the result of particles colliding with a certain minimum energy
Positive catalyst
A substance that increase the rate of a chemical reaction
without itself undergoing a permanent change
