Here are some useful physical constants, conversion factors, and unit prefixes. They are used in many calculations in chemistry, as well as in physics and other sciences.

### Useful Constants

Acceleration of Gravity | 9.806 m/s^{2} |

Avogadro's Number | 6.022 x 10^{23} |

Electronic Charge | 1.602 x 10^{-19} C |

Faraday Constant | 9.6485 x 10^{4} J/V |

Gas Constant | 0.08206 L·atm/(mol·K) 8.314 J/(mol·K) 8.314 x 10 ^{7} g·cm^{2}/(s^{2}·mol·K) |

Planck's Constant | 6.626 x 10^{-34} J·s |

Speed of Light | 2.998 x 10^{8} m/s |

p | 3.14159 |

e | 2.718 |

ln x | 2.3026 log x |

2.3026 R | 19.14 J/(mol·K) |

2.3026 RT (at 25°C) | 5.708 kJ/mol |

### Common Conversion Factors

Quantity | SI Unit | Other Unit | Conversion Factor |
---|---|---|---|

Energy | joule | calorie erg | 1 cal = 4.184 J 1 erg = 10 ^{-7} J |

Force | newton | dyne | 1 dyn = 10^{-5} N |

Length | metre or meter | ångström | 1 Å = 10^{-10} m = 10^{-8} cm = 10^{-1} nm |

Mass | kilogram | pound | 1 lb = 0.453592 kg |

Pressure | pascal | bar atmosphere mm Hg lb/in ^{2} | 1 bar = 10^{5} Pa1 atm = 1.01325 x 10 ^{5} Pa1 mm Hg = 133.322 Pa 1 lb/in ^{2} = 6894.8 Pa |

Temperature | kelvin | Celsius Fahrenheit | 1°C = 1 K 1°F = 5/9 K |

Volume | cubic metre | litre gallon (U.S.) gallon (U.K.) cubic inch | 1 L = 1 dm^{3} = 10^{-3} m^{3}1 gal (U.S.) = 3.7854 x 10 ^{-3} m^{3}1 gal (U.K.) = 4.5641 x 10 ^{-3} m^{3}1 in ^{3} = 1.6387 x 10^{-6} m^{3} |

### SI Unit Prefixes

Metric system or SI units are based on factors of ten. However, most units prefixes with names are 1000 times apart. The exception are near the base unit (centi-, deci-, deca-, hecto-). Usually, a measurement is reported using a unit with one of these prefixes.

Factors | Prefix | Symbol |
---|---|---|

10^{12} | tera | T |

19^{9} | giga | G |

10^{6} | mega | M |

10^{3} | kilo | k |

10^{2} | hecto | h |

10^{1} | deca | da |

10^{-1} | deci | d |

10^{-2} | centi | c |

10^{-3} | milli | m |

10^{-6} | micro | µ |

10^{-9} | nano | n |

10^{-12} | pico | p |

10^{-15} | femto | f |

10^{-18} | atto | a |