What is the equilibrium expression for the reaction `P_(4(s)) + 5O_(2(g))hArrP_(4)O_(10(s))` ?

Options

A. `K_(eq)=[O_(2)]^(5)`
B. `K_(eq)=(1)/(5)([P_(4)O_(10)])/([P_(4)][O_(2)])`
C. `K_(eq)=(1)/([O_(2)]^(5))`
D. `K_(eq)=([P_(4)O_(10)])/([P_(4)][O_(2)]^(5))`

Answer

C

Explanation

For pure solids such as `P_(4)O_(10)` and `P_(4)`, the active mass (expressed through density) is constant at a given temperature. For mathematical convenience, it is taken as unity (1). Thus, `K_(eq)= (1)/([O_(2)]^(5))`