Chemistry & Environmental Dictionary

Second Ionization Potential - Stoichiometry

Second Ionization Potential

To be defined

Short Term Exposure Limit (STEL)

The maximum exposure limit to a substance based on a 15 minute time weighted average.

Scientific Method

a research method that involves:

  1. Making an observation
  2. Developing a hypothesis
  3. Experimentation
  4. Testing and retesting (usually by many other scientists)
  5. Developing a theory
  6. If theory is proven beyond a doubt (e.g.: the law of gravity) a law may result (rarely does the scientific method reach this degree of acceptance as fact)


a uniformly dispersed mixture of molecules or ions. The substance being dissolved is the solute, while the substance into which the solute is dissolved is the solvent.

Specific Gravity

the ratio of the density of a substance to the density of a reference substance. Specific Gravity does not have any units. When water is used as the reference material, specific gravity equals density (without units).

Specific Gravity (SG) = (Density of substance g/ml)/(Density of reference substance g/ml)
Notice that g/ml cancels out so that there are no units associated with specific gravity. Specific Gravity then becomes an abstract number.

Specific Heat

the ratio of heat capacity of a substance to the heat capacity of water. Another way of looking at it is the quantity of heat required to raise the temperature of one gram of a substance by one degree centigrade or one degree Kelvin (1 J/gC = 1 J/gK).

Standard Temperature and Pressure (STP)

the standard conditions of 273.15 K and 1 atm (0°C at sea level). used as a baseline for calculations involving quantities that vary with temperature and pressure.


the quantitative relationship between chemical substances in a reaction.

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