Chapter 2.5-2.6: Life's Chemical Basis

solvent

Substance, typically a liquid, that can dissolve other substances; e.g., water

solute

A dissolved substance

hydrophilic

Describes a substance that dissolves easily in water; e.g., a salt
Having a strong affinity for water

hydrophobic

Describes a substance that resists dissolving in water; e.g., an oil
Lacking affinity for water

temperature

Measure of molecular motion

evaporation

Transition of a liquid to a gas; requires energy input

cohesion

Tendency of molecules to stick together under tension; a property of liquid water

hydrogen ions (H+)

an atom of hydrogen that has lost its electron. they are the key to the reactions of acids

hydroxide ions (-OH)

released from bases when added to water

pH scale

A measure of the number of hydrogen ions in a solution

acids

Any substance that releases hydrogen ions in water

bases

A substance that accepts hydrogen ions as it dissolves in water

salt

Compound that dissolves easily in water and releases ions other than H+ and OH-

buffer system

Set of chemicals that can keep the pH of a solution stable by alternately donating and accepting ions that contribute to pH