Question

When air is drawn into a car's engine, both N2 and O2 are present. During the combustion of the gasoline, oxygen reacts with the hydrocarbons in the fuel to produce carbon dioxide, carbon monoxide, and water. However, N2 and O2 can also form NO, one component of air pollution. N2(g) + O2(g) →2 NO(g)

a) At 25°C, the equilibrium constant, Kp, for this reaction is 4.0 x 10-31. What is/are the major species at equilibrium? b) Given that the reaction of N2 and O2 to produce NO has a Kp of 2.9 x 10-11 at 530°C, in which direction is the equilibrium shifted at high temperatures in the cylinders of a gasoline engine during combustion? Is the formation of NO endothermic or exothermic?

c) Propose ways to reduce the NO emission. Explain your reasoning.

Answer 1

N2 + O2 <---> 2NO

a)

Kp =p(No)^2 / p (N2) * P(O2)

since Kp is less than 1 , reactants will be in major form at equilibrium.

Major species are : N2 and O2

b)

At 25 oC Kp was 4*10^-31 and at 530 oC Kp is 2.9*10^-11. Since Kp has increased at high temperature. Reaction has shifted in forward direction.

Since by increasing Temperature reaction shift in forward direction, so it must be endothermic

c)

We saw that No is less if temperature is low. So No emission can be reduced if reaction occurs at lower temperature