What if the Equilibrium Expression Contains Only Gases

What if the Equilibrium Expression Contains Only Gases  

When an equilibrium expression contains only gases, we can write an alternate form of the 

Equation 15.3 An - moles of gaseous products - moles of gaseous reactants 

Because pressures are usually expressed in atmospheres, the gas eonstant R is expressed as 0.08206 L atm/K mol, and we can write the relationship between Kp and Kc as 

Kp is equal to K ordy in the special case where Aw = 0, as in the following equilibrium reaction  

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