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The conventions adopted in the entries include the following:

 ln x Natural logarithm of x (base e) log x Common logarithm of x (base 10) X ⦵ The standard-state value of the property X b ⦵ 1 mol kg−1 exactly c ⦵ 1 mol dm−3 exactly p ⦵ 1 bar exactly = An exact (defined) numerical value ≈ A derived or empirical numerical value $X ˜$ A quantity X expressed as a wavenumber (so the corresponding energy is $hc X ˜$ ⁠)
 ln x Natural logarithm of x (base e) log x Common logarithm of x (base 10) X ⦵ The standard-state value of the property X b ⦵ 1 mol kg−1 exactly c ⦵ 1 mol dm−3 exactly p ⦵ 1 bar exactly = An exact (defined) numerical value ≈ A derived or empirical numerical value $X ˜$ A quantity X expressed as a wavenumber (so the corresponding energy is $hc X ˜$ ⁠)

Many expressions in thermodynamics have the form $∑ J n J X J$, where J is a substance. This expression has the same form as a scalar product of the vectors n = {nA, nB, …} and X  = {XA, XB, …}. Therefore, it is possible to simplify the appearance of many expressions by replacing the sum by $n⋅X$. This alternative is provided as well as the conventional form.

A stoichiometric coefficient is a positive number; a stoichiometric number is a signed number, positive for products and negative for reactants. Both are dimensionless.

In accord with established convention, physical quantities are represented by oblique Greek or Roman symbols; labels, units, and mathematical constants are represented by upright Greek or Roman symbols.

Note that this book is a collection of concepts; only rarely does it include physical data. For the values of fundamental constants, see the Resource Section and the relevant entries.

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