Topics in Chemistry: Entropy, Acids, and Organic Compounds

Entropy

measure of the randomness or disorder in a system. A system with greater disorder has greater entropy.

Spontaneous Reactions

Exothermic reactions that result in increased entropy are

Arrhenius Theory

Behavior of many acids and bases can be explained by the - theory.

Electrolyte

substance which, when dissolved in water, forms a solution capable of conducting electricity. The ability to conduct electricity depends on the concentration of ions.

Arrhenius Acids

yield H+(aq) ions as the only positive ion in solution.

Hydronium Ions

ions may also be written as H3O+ (aq)

Arrhenius Bases

yield OH(aq) ions as the only negative ion in solution.

Neutralization Reactions

an Arrhenius acid and an Arrhenius base react to form salt and water.

Net Ionic Equation for Neutralization

all neutralization reactions is the same: H+(aq) + OH-(aq) → H₂O(l).

Titration

a lab process in which a volume of a solution of known concentration is used to determine the concentration of another solution.

Acidity and Alkalinity Measurement

a solution can be measured by pH.

Low pH

indicates a higher concentration of H+ ions than OH- ions.

High pH

indicates a lower concentration of H+ ions than OH- ions.

Neutral pH

indicates an equal concentration of H+ ions than OH- ions.

Pure Water pH

a neutral pH.

pH Scale

each decrease of one pH unit represents a tenfold increase in H+ ion concentration.

Redox Reaction

reaction involves the transfer of electrons (e-).

Reduction

the gain of electrons and decrease of oxidation number.

Oxidation

the loss of electrons and increase of oxidation number.

Electrochemical Cell

can be either voltaic or electrolytic.

Voltaic Cell

spontaneously converts chemical energy to electrical energy.

Electrolytic Cell

requires energy to produce a chemical change. This is called electrolysis.

Organic Compounds

consist of carbon atoms which bond to each other in chains, rings and networks to form a variety of structures.

Hydrocarbons

are compounds that contain only carbon and hydrogen.

Saturated Hydrocarbons

contain only single carbon-carbon bonds.

Unsaturated Hydrocarbons

contain at least one multiple carbon-carbon bond (double or triple bond).

Functional Groups

give organic molecules distinct physical and chemical properties.