Unit 12 Kinetics Quiz Flashcards
Explain the meaning of the “rate of a chemical reaction”. Give an example of a slow reaction and a fast reaction:
•rate = change in concentration of a reactant or product per unit time
- fast —> any double replacement; combustion
- slow —> rusting, fossil fuel formation
What are two characteristics of an effective collision?:
- particles collide with sufficient energy (activation energy)
- particles collide with the correct orientation
to form the activated complex
What property of a molecule changes when the speed of a molecule changes?:
kinetic energy
Consider the reaction A + B = C + D
State two reasons why a collision between molecules A and B many not be effective:
- wrong orientation
* insufficient energy
What is an activated complex?:
Transition state between reactants and products (must be formed in order to form product)
Define activation energy:
The minimum energy particles must collide with in order to form the activated complex
List seven factors that affect the rate of a chemical reaction:
- nature of reactants
- concentration
- pressure (gases)
- surface area (particle size)
- temperature
- catalysis
- agitation
Explain why a given mass of magnesium will react faster when broken into small pieces than when it is in the form of a single ribbon:
Particles can only react with a solid on its surface. When the magnesium is broken into smaller pieces parts of the Mg that were inside are now on the surface. This increases the probability of collision and therefore increases rate.
In terms of collision theory, explain why the rate of a reaction increases when the temperature is increased:
Increasing temperature increases particle speed. This means they will collide more frequently and a greater percentage of these collisions will have enough energy to form the activated complex.
Define catalyst:
A substance which speeds up a reaction but is not consumed by the reaction
