J.R. S. answered 05/02/20
Ph.D. University Professor with 10+ years Tutoring Experience
Gaseous reactions do not use brackets, but rather use parentheses and P.
For 2NO2(g) + F2(g) ==> 2NO2F(g), the generalized rate equation would be:
rate = k(PNO2)a(PF2)b or...
rate = k(NO2)a(F2)b