Factors that affect The rate
- Temperature- Increasing temp ALWAYS increases the rate of a reaction.
- Surface Area- Increasing the surface area increases the rate of the reaction.
- Concentration - Increasing concentration USUALLY increases the rate of the reaction.
- Presence of a Catalyst
Catalysts
A substance that speeds up a reaction with out being consumed itself in the reaction.
Enzyme- A large molecule ( usually protien) that catalyzes biological reactions
- Human body temp = 37 degrees C
Inhibitors- interfere with the action of a catalyst; reactions slow or even stop.
A substance that speeds up a reaction with out being consumed itself in the reaction.
Enzyme- A large molecule ( usually protien) that catalyzes biological reactions
- Human body temp = 37 degrees C
Inhibitors- interfere with the action of a catalyst; reactions slow or even stop.
Reversible Reactions
- Some reactions do not go to completion as we have assumed… some may be reversible
- The 2 equations can be combined into one, by using a double arrow, which tells us that it is a reversible reaction
- Just because the rate are equal on the forward and backward of the reaction are equal the concentrations on each side might be difference, then it would be shown where the forward or backward reaction will be have an arrow longer than the opposite. Usually the side with the higher concentration is favored.
Le Chatelier's Principle
Le Chatelier studied how the equilibrium position shifts as a result in a change in the conditions.
His Principle: If stress is applied to a system in equilirium, the system changes in a way that relieves the stress.
What does he mean when he mentions "stress"
Types of stress include
His Principle: If stress is applied to a system in equilirium, the system changes in a way that relieves the stress.
What does he mean when he mentions "stress"
Types of stress include
- Concentration-- Adding more reactant produces more product, and removing the product as it's being formed will produce more product.
- Temperature-- increasing the temperature causes the equilibrium position to shift in the direction that absorbs heat.
- Pressure-- changes in pressure will only effect gaseous equilibria
Equilibrium Constants :)
- The values relate to the amounts ( Molarity ) of reactants and products at equilibrium, this is called the equilibrium constant which is a K with a subscript of ' eq '
Consider the equation where the lower case letters are coefficients, and capital letters are the chemicals.
aA + bB <--> cC +dD
to find the Equilibrium constant
Keq = [C]^c x [D]^d
[A]^a x [B]^b where the brackets [-] = molarity concentration.
to show which arrow ( forward or backward ) is favored then…
if
Keq > 1 PRODUCTS are favored
Keq < 1 Reactants are favored
Information was presented in class.