PHYSICAL CHEMISTRY IN BRIEF

CHAP. 8: CHEMICAL EQUILIBRIUM [CONTENTS] 238

Note:Since further on in this chapter we will deal solely with states at equilibrium, the

subscripteqwill be omitted.

The relation (8.14) may thus be also written as

∆rGst=−RTlnK. (8.16)

The value of the equilibrium constant is determined by:

• thestandard state


• thestoichiometric coefficientsin the chemical reaction.

Example

If we multiply a chemical equation by two, we get

∆r, 2 Gst= 2∆r, 1 Gst

and from this we have for equilibrium constants [compare (8.16)]

K 2 =K 12.

8.2.7 Reactions in the gaseous and liquid phases

The exact relations for equilibrium constants, simplified relations for ideal cases, and symbols

for individual standard states together with other information are given in tables on pages 241

and 242.

Note:The symbol

∆ν=

∑k

i=1

νi

denotes a change in the total amount of substances.

S Symbols: For the standard state of a pure component at the temperature and pressure of the
system, the superscriptstis replaced with the superscript•, the respectiveγis without any
subscript or superscript.