Mathematics revision - Chemical Fundamentals of Geology and Environmental Geoscience - page 233

APPENDIX A: MAthEMAtIcs rEvIsIoN

SI units of measurement

The kelvin is the unit of temperature measured from
absolute zero. T (K) = T (°C) + 273.15. Degrees Celsius
(°C) continue to be widely used by geoscientists.
Volume is expressed in m 3 ; in solution chemis-
try (Chapter 4), the litre (L) has been superseded
by dm 3 (cubic decimetres) in SI notation:
1 dm 3 = 10 −3 m 3 = 1 litre.
(b) Names are given to various 'derived' SI units (all
named after scientific luminaries of the past) which
consist of combinations of the basic units above.
The derived units are inconvenient to remember at
first, but make the system much more concise to
use - see Table A2 for examples.
Notice that some derived units have several equiv-
alent forms and may be expressed in alternative
ways, either in the basic units or in terms of other
derived units. An example is the constant g , the accel-
eration due to gravity, which may be expressed m s −2
or as N kg −1 , the two forms being exactly equivalent.

In 1960, the Système International d'Unités ('SI units')
convention was introduced to promote standardiza-
tion between sciences. The following are the most
important features (full details are available at http://
physics.nist.gov/cuu/Units/introduction.html ):

(a) The basic units are as given in Table A1.

Table A1 Basic SI units

Dimension Unit Abbreviation

Length metre m

Mass kilogram kg

Time second s

Electric current ampere A

Temperature kelvin K

Amount of substance mole mol