This document lists several important physical constants and conversion factors used in chemistry. It includes the ionization constant of water, molar volume of gases, speed of light, specific heat capacity, Avogadro's number, Faraday's constant, Planck's constant, Rydberg constant, ideal gas constant, density of water, freezing point of water, and vapor pressure of water. Conversion factors provided relate units of volume, energy, pressure, and temperature.

1. LIST OF SELECTED CONSTANT VALUES
Ionization constant for water at 25⁰C Kw = 1.0 x 10-14 mol2 dm-6
Molar volume of gases Vm = 22.4 dm3 mol-1 at STP
Speed of light in a vacuum c = 24 dm3 mol-1 at room
condition (25⁰C, 1 atm)
Specific heat capacity c = 4.18 kJ kg-1 K-1
= 4.18 J g-1 K-1
= 4.18 J g-1 ⁰C-1
Avogadro’s number NA = 6.02 x 1023
Faraday constant F = 96 500 C mol-1
Planck constant h = 6.63 x 10-34 J s
= 6.63 x 10-34 Kg m2 s-1
Rydberg constant RH = 1.097 x 107 m-1
= 2.18 x 10-18 J
Ideal gas constant R = 8.314 m3 Pa mol-1 K-1
= 8.314 J mol-1 K-1
= 0.08206 L atm mol-1 K-1
= 62.36 L mmHg mol-1 K-1
Density of water at 25⁰C Ρ = 1 g cm-3
Freezing point of water = 0.00 ⁰C
= 273.15 K
Vapour pressure of water at 25⁰C PH2O = 23.76 torr

2. UNIT AND CONVERSION FACTOR
Volume 1 L = 1 dm3
1 mL = 1 cm3
Energy 1 J = 1 kg m2 s-2
= 1 N m
= 1 x 107 erg
1 calorie = 4.184 J
1 eV molecule-1 = 96.7 kJ mol-1
Pressure 1 atm = 760 mmHg
= 760 torr
= 101 325 Pa
= 101 325 Nm-2
Temperature 0 ⁰C = 273.15 K
OTHERS 1 faraday (F) = 96 500 C
1 newton (N) = 1 kg m s-2