CHEM111 CHAPTER 13-14 Flashcards
Reaction rate
Speed of a chemical reaction; occur when atoms or molecules collide but only when there is enough energy and at an orientation that allows the rearrangement to take place
Collision theory
Theory that states that for a reaction to occur, reactant particles must collide and collision must have a certain minimum amount of energy; Activation Energy
3 major factors that affect collisions and rates of chemical reaction:
- Concentration
- Temperature
- Energy changes
Factors that affect reaction rates (4):
- Physical state: solid, liquid, gas
- State of subdivision, size of particles
- Solid reactions occur at surfaces which increases surface area and increases rate of reaction
- Gas phase reactions tend to react faster than solid or liquid phase
Effects of concentration (2):
- Low concentration = fewer collisions
- High concentration = more collisions
Effects of increased temperature (2):
- Lower temperature, = less kinetic energy = fewer collisions
- Higher temperature = more kinetic energy = more collisions
Transition state
The highest energy arrangement of atoms that occurs during a chemical reaction
Activation energy
The energy barrier for a reaction. This energy determines how quickly a reaction occurs. Reaction rates depend on the concentration and the activation energy
Catalysts
Substance that when added to a chemical reaction speeds up rate of reaction but is itself unchanged after the reaction is completed (Catalysts lower activation energy needed of a reaction and provides an alternate pathway for reaction)
Equilibrium reaction
Reactions that can go in the forward direction and also backwards represented by a double arrow. Side of equilibrium with lower energy has greater concentration and vice versa
How does the changing concentrations affect rate of for the forward and reverse reactions
As the concentration of reactants decreases expect the rate of the forward reaction to decrease. As the concentration of the products increases, expect the rate of the reverse reaction to increase
The Equilibrium equation
Just remember that right side of equation goes on numerator and left side is bottom and its the one with [][]/[][] with powers raised
Solubility product
The equilibrium constant for the solution of a slightly soluble ionic compound
Le Chatelier’s Principle
States that if one or more particular substance (reactant or product) is added to the system, equilibrium will shift to use up that substance
A + B + heat = C is an example of
Endothermic
E + F = G + heat is an example of
Exothermic
Shifts in equilibrium (3):
- Adding to an equilibrium pushes it towards the other side
- Heating shifts an equilibrium towards the higher energy side
- High pressure shifts equilibria towards the side with fewer moles of gas
Oxidation - Reduction reactions
A chemical change in which one species loses electrons (oxidation), while another gains electrons (reduction); also called redox reactions
Oxidation
Loss of electrons
Reduction
The gain of electrons
Oxidizing agent
Takes electrons
Reducing agent
Loses electrons
Types of redox reactions (4):
- Disproportionation reactions
- Metals as reducing agents; reactions of metals with acids, reactions of metals with aqueous metal salts
- Reaction of two nonmetals
- Reaction of metal salts and non metals in acid solution
Disproportionation reactions
Reactions in which atoms of a single element undergo both oxidation and reduction
