Question

Write a paragraph to explain to a friend (who is not in the class) or a family member why air pollution caused by NO 2 (g) is worse in hot weather, and why the air takes on a reddish-brown color. (N2O4 (g) --> 2NO2 (g)) Use heats of formation, Gibbs's energy, entropy, and enthalpy in your explanation.  

How can you use the Gibbs energy to predict if a process results in mainly reactants, mainly products, or a mixture of the two? (paragraph format)

Answer 1

Recall that:

N2O4 (g) --> 2NO2 (g)

HRxn = 2NO2 - N2O4 = 2*33.2 - 11.1 = 55.3 kJ/mol

dG = 2NO2 - N2O4 = 2* 240.1 - 304.4 = 175.8 kJ/mol

note that the reaciton is endothermic

which explains why in summer ( there is high temperature, i.e. heat is readily available)

then

the reacito proceeds forwad, producing more NO2, which is borwn/red coloured

Also from dG values this is not favoured, unles T is high, then

dG becomes negative, which ipmlies spontanoues NO2 produciton in summer