21.4: Units and Conversion Factors
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| Units of Length | |||
|---|---|---|---|
| meter (m) |
= 39.37 inches (in.)
|
angstrom (Å) |
= 10
–8
cm (exact, definition)
|
| centimeter (cm) | = 0.01 m (exact, definition) | yard (yd) | = 0.9144 m |
| millimeter (mm) | = 0.001 m (exact, definition) | inch (in.) | = 2.54 cm (exact, definition) |
| kilometer (km) | = 1000 m (exact, definition) | mile (US) | = 1.60934 km |
| Units of Volume | |||
|---|---|---|---|
| liter (L) |
= 0.001 m
3
(exact, definition)
|
liquid quart (US) |
= 32 (US) liquid ounces (exact, definition)
|
| milliliter (mL) |
= 0.001 L (exact, definition)
|
dry quart | = 1.1012 L |
| microliter (μL) |
= 10
–6
L (exact, definition)
|
cubic foot (US) | = 28.316 L |
| Units of Mass | |||
|---|---|---|---|
| gram (g) | = 0.001 kg (exact, definition) | ounce (oz) (avoirdupois) | = 28.35 g |
| milligram (mg) | = 0.001 g (exact, definition) | pound (lb) (avoirdupois) | = 0.4535924 kg |
| kilogram (kg) |
= 1000 g (exact, definition)
|
ton (short) |
=2000 lb (exact, definition)
|
| ton (metric) |
=1000 kg (exact, definition)
|
ton (long) |
= 2240 lb (exact, definition)
|
| Units of Energy | |
|---|---|
| 4.184 joule (J) | = 1 thermochemical calorie (cal) |
| 1 thermochemical calorie (cal) | = 4.184 × 10 7 erg |
| erg | = 10 –7 J (exact, definition) |
| electron-volt (eV) | = 1.60218 × 10 −19 J = 23.061 kcal mol −1 |
| liter∙atmosphere | = 24.217 cal = 101.325 J (exact, definition) |
| nutritional calorie (Cal) | = 1000 cal (exact, definition) = 4184 J |
| British thermal unit (BTU) | = 1054.804 J 1 |
| Units of Pressure | |
|---|---|
| torr | = 1 mm Hg (exact, definition) |
| pascal (Pa) |
= N m
–2
(exact, definition)
|
| atmosphere (atm) |
= 760 mm Hg (exact, definition)
|
| bar |
= 10
5
Pa (exact, definition)
|
Footnotes
- 1 BTU is the amount of energy needed to heat one pound of water by one degree Fahrenheit. Therefore, the exact relationship of BTU to joules and other energy units depends on the temperature at which BTU is measured. 59 °F (15 °C) is the most widely used reference temperature for BTU definition in the United States. At this temperature, the conversion factor is the one provided in this table.