Data reference—Important constants and standards

Data sheets supply constants such as R, F, Nₐ, electronic charge, molar gas volumes, Kᵥ and the specific heat capacity of water. Use the value only with the equation and conditions it belongs to.

Check units before substituting: R depends on the pressure/volume unit system, molar gas volume depends on temperature and pressure, and c for water is used with mass and temperature change in q = mcΔT.

Use F in Q = nF for charge per mole of electrons; use the supplied room-temperature molar volume rather than the s.t.p. value when the question states room conditions.

A constant is not unit-free or universal across conditions; copying a familiar number without checking the data sheet can create a systematic error.