Science / Chemistry Glossary

Standard Solution: A solution of precisely known concentration.

Standard State: A set of conditions defined to allow convenient comparison of thermodynamic properties. The standard state for a gas is the the state of the pure substance in the gaseous phase at the standa . . . View Full Definition

Standard Temperature And Pressure: Used to describe a substance at standard pressure and a temperature of 0°C (273.15 K).

Starch: A polysaccharide used by plants to stockpile glucose molecules. The most common forms are amylose and amylopectin.

State Function: A property that depends only on the condition or 'state' of the system, and not on the path used to obtain the current conditions. Energy, enthalpy, temperature, volume, pressure, and temper . . . View Full Definition

State Of Matter: There are three common states of matter: gases, liquids, and solids. States of matter differ in the way the molecules are arranged at the molecular level, but not in the structure of the mol . . . View Full Definition

Stationary Phase: A stationary phase is a substance that shows different affinities for different components in a sample mixture in a separation of the mixture by chromatography. The mobile phase (a solution . . . View Full Definition

Steel: An alloy of iron and carbon. Steel contains anywhere between 0.2% carbon (for soft wire and sheet steel) and 1.5% carbon (for cutting tools), with small amounts of many other elements often present.

Steradian: A solid angle with vertex at the center of a sphere of radius r that encompasses an area of r2 on the surface of the sphere.

Stereochemistry: Stereochemistry is the study of how the properties of a compound are affected by the spatial positions of groups within its molecules. Stereochemistry is also concerned with determining the . . . View Full Definition

Stereoisomer: Molecules with the same atoms and bond structure, but different three dimensional arrangements of atoms. For example, the CH3 groups in CH3CH=CHCH3 can be placed on the same side of the doub . . . View Full Definition

Stoichiometric Coefficient: The coefficients given before substances in a balanced chemical equation. For example, the stoichiometric coefficient of carbon dioxide in the following reaction is 4: 2 C2H6(g) + 7 O2(g) ri . . . View Full Definition

Stoichiometry: 1. Ratios of atoms in a compound. 2. Ratios of moles of compounds in a reaction. 3. A branch of chemistry that quantitatively relates amounts of elements and compounds involved in chemical r . . . View Full Definition

Stripping: Stripping is a technique for removing volatile components in a mixture by bubbling a stream of an chemically unreactive gas (like nitrogen) through the sample, and then 'scrubbing' the nitro . . . View Full Definition

Strong Acid: A strong acid is an acid that completely dissociates into hydrogen ions and anions in solution. Strong acids are strong electrolytes. There are only six common strong acids: hcl (hydrochlori . . . View Full Definition

Strong Base: A strong base is an base that completely dissociates into ions in solution. Strong bases are strong electrolytes. The most common strong bases are alkali metal and alkaline earth metal hydroxides.

Strong Electrolyte: A strong electrolyte is a solute that completely dissociates into ions in solution. Solutions of strong electrolytes conduct electricity. Most soluble ionic compounds are strong electrolytes.

Strong Ligand: A ligand that causes a large crystal field splitting which results in a low-spin complex.

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