Nitric oxides, NO
and NO2
, contribute to air pollution, acid rain, and the depletion of the ozone layer. After NO
forms in the combustion chamber of an automobile engine, it reacts further with oxygen to form NO2
. The reaction is given by
2NO(g)+O2(g)→2NO2(g)

The following table gives some entropy values:

Substance
S∘ (J/mol⋅K)
NO2
240.0
O2
205.2
NO
210.8
Part A
Calculate ΔSrxn∘
for the reaction
2NO(g)+O2(g)→2NO2(g)

Express your answer to one decimal place and include the appropriate units.