Unit 15: Reaction Rates and Equilibrium Flashcards
(34 cards)
Collision Theory of Reactions
A chemical reaction only takes place if collisions between molecules have the right energy and the right orientation
Activation Energy
the minimum energy needed for a reaction to take place upon proper collision of reactants
Reaction Rate
- the speed at which reactant is used up
- the speed at which product forms
When temperature increases the reaction rate…
increases
Why does the reaction rate increase when temperature increases?
molecules move FASTER, providing more colliding molecules with energy of activation
When concentration of reactant increases the reaction rate…
increases
Why does the reaction rate increase when the concentration increases?
increases the number of collisions and increases the amount of product
Qualities of a catalyst (3)
- Speeds up the rate of a reaction.
- Lowers the energy of activation.
- Is not used up during the reaction.
The smaller the particle size the ____ the reaction rate
higher
Why do smaller particles allow for increased reaction rates?
SMALLER particle size = HIGHER surface area for a given mass of particles.
What can increase surface area of particles?
dissolving or by grinding into a fine powder
When equilibrium is reached…
There is NO CHANGE in the amounts of reactant and product.
If equilibrium is reached after most of the forward reaction has occurred, the system favors…
the product
A large Kc favors…
the product
If equilibrium is reached when very little of the forward reaction has occurred, the reaction favors…
the reactants
A small Kc favors…
the reactants
LeChatelier’s Principle
- any change in equilibrium conditions upsets the equilibrium of the system
- there will be a change in the rate of the forward or reverse reaction to return the system to equilibrium
If more reactant is added…
- increase the number of collisions between reactants
- shifts toward the product
If more product is added…
- increase the number of collisions between products
- shifts toward the reactant
If reactant is removed…
- decreases the collisions between reactants
- shifts the equilibrium toward the reactant
If product is removed…
- less collisions between products
- shifts toward the products
Decrease in volume…
shifts the equilibrium toward the fewer number of moles
Increase in volume…
shifts equilibrium toward the higher number of moles
At equilibrium…
the rate of the forward reaction becomes equal with the rate of the reverse reaction
