Measures changes that occur within intervals of time.
A measure of how quickly a reactant is consumed or how quickly a product is formed.
Steeper slopes on a graph equal...?
Faster reaction rate
Why do reactions always slow down ?
You run out of reactants.
Molecules that collide to react. - The greater number of collisions occuring per second, the greater the reaction rate. - For most collisions, only a tiny fraction of the collisions actually lead to a reaction.
Colliding molecules must have total kinetic energy equal to or greater than some minimum value in order to break existing bonds.
Molecules must also be oriented in a certain way for the collision to lead to a reaction.
Factors Affecting Reaction Rate
Concentration of reactants, Temperature, Surface area of solid, Presence of a catalyst.
Concentration of Reactants
Most reactant proceed faster if the concentration of one or more of the reactants is increased.
Rate usually increases with an increase in temperature
Surface area of a solid
The more surface area the faster the reaction will occur
Presence of a catalyst
Speeds up a reaction by reducing the activation energy
When rates of the forward and reverse reaction are equal
The reaction occurs in both directions simultaneously.
What two things happen at equilibrium?
1) Forward and reverse equal each other. 2) Consentration stays the same.
Equilibrium constant Keq
Ratio of products concentrations to reactants concentrations, with each concentration raised to a power given by the number of moles of that substance.
If Keq is > 1...
Products favored at equilibrium
If Keq < 1...
Reactants favored at equilibrium
What are the only terms you put in your expression?
Gases and aq ( Not solids and liquids)
If a system at equilibrium is disturbed by a change in temperature, pressure, or the concentration of one of the componenets, the system will shift its equilibrium position so as to counteract the effect of the disturbance.
Facotrs affecting equilibrium
1) Change in concentration 2) Change in temperature 3) Change in pressure.
If you increase pressure ....
The arrow wil go tot the side of the reaction with the least number of moles of gas.
A quantitative measure of the disorder of a system
Law of disorder
Things move in the direction of maximum disorder or randomness
Change in Entropy
Increases from solid to liquid to gas. - More particles, more entropy.