say we have a reaction N2O4 reversible 2NO2

for this reaction,if initial number of moles of N2O4 is 'a' can we write

t = 0 a -

at equilbrium a-x 2x

similarly can we do the same for pressure? i.e. if initial pressure is p,then can we say?

t=0 p -

at equilbrium p-y 2y

if yes why? and is x=y,i.e is the number of moles of x dissociated equal to decrease in pressure of reactant? and is this method valid for all reversible reaction irrespective of the stoichiometric coefficient of reactants and products


1 Answer 1


If you assume ideal gas in a constant volume this works, but x is not y. 'a' and 'p' are related via the ideal gas law(a = n): P = n * R*T/V .

Take in mind that the pressure actually increases as the reaction progesses as more particles are formed.


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