Question

At a certain temperature, the equilibrium constant for the following chemical equation is 2.40. At this temperature, calculate the number of moles of NO2(g) that must be added to 2.53 mol of SO2(g) in order to form 1.10 mol of SO3(g) at equilibrium.

Answer 1

NO2 + SO2 < -- > SO3 + NO
n 2.53 0 0 intially
n-x 2.53 - x x x at equlibrium

given,
number of mole of SO3 at equlibrium = 1.10
x = 1.10
so,
number of mole of SO2 at equlibrium = 2.53-x
= 2.53-1.10
= 1.43
number of mole of NO at equlibrium x
= 1.10
number of mole of NO2 at equlibrium = n-x
= n-1.10

Kc = ([SO3]*[NO])/([NO2]*[SO2])
2.40 = (1.10*1.10)/{(n-1.10)*1.43}
n-1.10 = 2.84
n = 3.94 mole

number of mole of NO2 intial = n
= 3.94 mole

Answer : 3.94 mole