Question

NO2 is one of the atmospheic pollutants produced by automobiles. It is formed when the high temperature in the internal combustion engine causes atmospheric N2 and O2 to combine to produce NO, which then reacts with more O2 to give NO2. This pollutant ultimately is converted to HNO3. Aproposed equation for this convertion at 2989 K is

O3(g) +2NO2(g)+H2O(g)--------- 2HNO3(aq)+O2(g). Calculate the enthalpy for the conversion reaction

Answer 1

Hi, the enthalpy for the conversion reaction can be calculated as:

Individual standard state enthalpies can be seen from standard tables. I found the following values from wikipedia:

Note that variuos tables may have slightly different values.

H (O₃) = 143.0 kJ/mol

H (NO₂) = 33.2 kJ/mol

H (H₂O) = −241.8 kJ/mol

H (HNO₃) = -207.4 kJ/mol

H (O₂) = 0.0 kJ/mol

ΔH = {(2x-207.4)+(0.0)} - {(143.0)+(2x33.2)+(−241.8)} = -733.2 kJ/mol

Should you require any other information, I will be more than happy to help.