COLLISION THEORY Flashcards
(13 cards)
is a theory that was proposed independently by Max Trautz in 1916 and William Lewis in 1918.
collision theory
states that when suitable particles of the reactant hit each other, only a certain fraction of the collisions cause any noticeable or significant chemical change; these successful changes are called SUCCESSFUL COLLISIONS.
collision theory
The successful collisions must have enough energy, also known as ___________, at the moment of impact to break the pre-existing bonds and form all new bonds. This results in the products of the reaction.
activation energy
Increasing the concentration of the reactant particles or raising the temperature - which brings about more collisions and hence more successful collisions - therefore increases the rate of a reaction.
true
When a CATALYST is involved in the collision between the reactant molecules, LESS ENERGY is required for the chemical change to take place, and hence more collisions have sufficient energy for reaction to occur. The REACTION RATE therefore INCREASES.
true
For a reaction to occur, the atoms or molecules must collide with one another with enough energy (activation energy) and must collide in the right orientation.
collision theory
Factors that affect KINETICS
FACTORS:
1)Concentration of reactants
2)Temperature
3)Presence of a catalyst
4)Surface area
5)Agitation
6)Nature of reactants
If you INCREASE CONCENTRATION (Molarity), the RATE OF REACTION INCREASES
Why? There are more molecules which increases the number of collisions altogether; however, there are better chances that molecules will collide in the right orientation.
concentration of reactants
Temperature is an averaged kinetic energy of molecules so if you INCREASE TEMPERATURE, you INCREASE KINETIC ENERGY. This means you INCREASE the NO. OF COLLISIONS
Heat supplies the energy to allow the reaction to proceed (i.e. overcoming the
activation energy barrier)
Think about: Why do we refrigerate milk?
temperature
Catalyst assist a reaction and increase the reaction rate without being consumed in the reaction.
Adding a catalyst DECREASES the ACTIVATION energy which means more molecules will have ENOUGH ENERGY TO REACT
Think about: Catalytic converter, Enzymes
presence of a catalyst
Increased surface areas of molecules/particles will increase the rate of reaction. This
means to break into smaller particle sizes.
More places to react give better chances for collisions in the right orientation. How to increase surface area? Grind or crush a mixture of reactants.
surface area
Stirring or shaking a reaction will increase the reaction rate.
By stirring or shaking, you are introducing energy into the reaction and thus giving molecules/particles more energy to react (overcome activation energy barrier). Your mechanical energy is converted to kinetic energy.
agitation
Reactants whose bonds are weaker have a lower activation energy and thus a higher rate of reaction.
All chemical reactions involve bond breaking and bond making. Bond breaking occurs on reactant side. Collisions between reactants that require less kinetic energy are needed to break weaker bonds (i.e. smaller activation energy)
nature of reactants
