General Chemistry/Units

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SI Fundamental Units[edit]

These are the seven basic SI units from which all other units are constructed.

Quantity Symbol Unit Unit Symbol
Length l metre m
Time t second s
Mass m kilogram kg
Thermodynamic temperature T kelvin K
Amount n mole mol
Electrical charge Q coulomb C
Luminous intensity IV candela cd

SI Derived Units[edit]

All other units are derived units. They are built from fundamental units. This is a small selection of units that may be found in General Chemistry.

Quantity Symbol Unit Unit Symbol Derived From
Force F newton N kg·m·s-2
Energy U joule J kg·m2·s-2
Pressure P pascal Pa kg·m-1·s-2
Power watt W kg·m2·s-3
Electrical current I ampere A C·s-1
Electrical potential V volt V J·C-1

SI Prefixes[edit]

A prefix appears before a unit's symbol when expressing very large or very small quantities. For example: 0.001 kg = 1 g = 1000 mg.

1000n 10n Prefix Symbol Decimal
10008 1024 yotta Y 1 000 000 000 000 000 000 000 000
10007 1021 zetta Z 1 000 000 000 000 000 000 000
10006 1018 exa E 1 000 000 000 000 000 000
10005 1015 peta P 1 000 000 000 000 000
10004 1012 tera T 1 000 000 000 000
10003 109 giga G 1 000 000 000
10002 106 mega M 1 000 000
10001 103 kilo k 1 000
102 hecto h 100
101 deca da 10
10000 100 (none) (none) 1
10−1 deci d 0.1
10−2 centi c 0.01
1000−1 10−3 milli m 0.001
1000−2 10−6 micro µ 0.000 001
1000−3 10−9 nano n 0.000 000 001
1000−4 10−12 pico p 0.000 000 000 001
1000−5 10−15 femto f 0.000 000 000 000 001
1000−6 10−18 atto a 0.000 000 000 000 000 001
1000−7 10−21 zepto z 0.000 000 000 000 000 000 001
1000−8 10−24 yocto y 0.000 000 000 000 000 000 000 001

Solution Concentration Units[edit]

Quantity Symbol Units Description
Molarity M mol/L moles of solute per liter of solution
Molality m mol/kg moles of solute per kilogram of solvent
Mole Fraction χ (none) moles of solute per moles of solution
Parts per million ppm (none) milligrams of solute per kilogram of solution
Parts per billion ppb (none) micrograms of solute per kilogram of solution

Other Useful Units[edit]

Volume[edit]

Volume Unit Conversion Mass of Water (4 °C)
1 L = 1000 cm3 1 kg
1 cm3 = 1 m/L 1 kg
1 m3 = 1000 L 1000 kg

Pressure[edit]

Name Symbol Conversion
Atmosphere atm = 760 torr = 101.325 kPa
Pascal Pa ≈ 7.5 x 10-3 torr
Torr (mm Hg) torr ≈ 133.3 Pa
Pound-per-square inch psi ≈ 51.7 torr ≈ 6.894 kPa

Temperature[edit]

One degree Celsius is equal to one Kelvin (in magnitude).

Name Symbol Abs. Zero M.P. of Water B.P. of Water
Fahrenheit °F -456.67 °F 32 °F 212 °F
Celsius °C -273.15 °C 0 °C 100 °C
Kelvin K 0 K 273.15 K 373.15 K

* Notice it is not "degrees Kelvin".