Question

The first step in smog formation in Southern California is

N₂(g) + O₂(g) ⇋ 2 NO(g).

a) From the temperature and K_P data provided below, graphically determine the values of D_rxnH° and D_rxnS° for the reaction.

T/K	1900	2000	2100	2200	2300	2400	2500	2600
KP/10-4	2.31	4.08	6.86	11.0	16.9	25.1	36.0	50.3

b The temperature of car exhaust is 500°C. What are the values of K_P and D_rxnG at this temperature?

c. At what temperature does the value of D_rxnG change sign?

d.The Southern California Air Quality Management District (SCAQMD) is considering requiring car manufacturers to have engines run at lower temperatures to reduce the amount of NO formed. If they require car exhaust not exceed 400°C, how much NO would form relative to the amount formed at 500°C?

Key points: write out the equilibrium constant expression in terms of the reactants and products.

Key points: mass is conserved.

Key points: assume air pressure is 1 atm, 20.95% is oxygen and 78.09% is nitrogen.

e. Based on your answer to b, do you think the SCAQMD should push for this change? Explain.

Answer 1