General Chemistry 2 Ch14

Chapter 14

Chemical kinetics

The study of how fast chemical reactions occur.

What are the four chemical kinetics?

Concentraction of reactions, temperature, presence of a catalyst, and surface area of a solid reactant or catalyst

Catalyst

A substance that increases the rate of a reaction without being consumed in the overall reaction

Reaction rate

a) The increase in the molar concentration of product of the reaction per unit time

b) The decrease in molar concentration of reactant per unit time

Instantaneous rate

The tangent to the curve at any given time

Rate Law

A equation tha trelated the rate of a reaction to the concentrations of reactants (and catalyst) raided to various powers

Rate constant

Proportionality constant in the relationship between rate and concentration

Reaction order

With respect to each given reactant species equals the exponent of the concentration of that species in the rate law, as determined experimentally

Half life

Is the time it takes for the reaction concentration to decrease to one half its initial value

Collision Theory

In order for a reaction to occur, reactant molecules must collide with an energy greater than some minimum value and with teh proper orientation

Energy of activation

The minimum energy of collision required for two molecules to react

Arrhenius Equation

A mathematical equation that expresses the dependence of the rate constant
lnk =lnA - (Ea/Rt)

Elementary reaction

Is a singular molecular event, such as a collision of molecules, resulting in a reaction

Reaction intermediate

A species produced during a reaction that does not appear in the net equation because it reacts in a subsequent step in the mechanism

Catalysis

The increase in the rate of a reaction as a result of the addition of a catalyst

Molarity

The number of molecules on the reactant side of an elementary reaction

Rate Determining Step

The slowest step in the reaction mechanism

Transition-State Theory

Explains the reaction resulting from the collision of two molecules in terms of an activated complex

Activated Complex

An unstable group of atoms that can break up to form products. The halfway point of an elementary process

Chemical Equilibrium

Is the state reached by the reaction mixture when the rates of the forward and reverse reactions have become equal

Homogeneous equilibrium

An equilibrium that involves reactants and products in a single phase

Heterogeneous equilibrium

An equilibrium that involves reactants and products in more than one phase

Le Chatelier’s Principle

When a system in chemical equilibrium is disturbed by a change of temperature, pressure, or concentration, the system at equilibrium will shift in a way that counteracts this change of variable

Arrhenius Acid

Is a substance, that when dissolved in water, increases the concentration of hydrogen ion, H^+

Arrhenius base

Is a substance, that when dissolved in water, increases the concentration of hydroxide ion, OH^-

Conjugate acid

consists of two species in an acid-base reaction, one acid and one base, that differ by the loss or gain of a proton

Bronsted Acid

Is a proton (H^+) donor in a proton transfer reaction

Bronsted base

is a proton (H^+) acceptor in a proton transfer reaction

Amphiprotic species

Can act as either an acid or a base (it can lose or gain a proton), depending on the other reagent

Lewis acid

Is a species that forms a covalent bond by accepting an electron pair from another species

Lewis base

Is a species that can form a covalent bond b donating an electron pair to another species

Acid Base Indicators

Are dyes that are weak acids or bases themselves. The acid form has a different color than the base