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Chemical reactions

Reaction coefficients are in units of s-1 for unimolecular reactions, cm3 molecule-1 s-1 for bimolecular reactions, and cm6 molecule-2 s-2 for termolecular reactions. Reaction steps labelled as "Immediate" are given for clarity only.

Table 1.2: Photo-oxidant Chemistry: Lagrangian Model
Rate coefficient Reaction
"t" is temperature, M is third body.
Generic reaction rates  
Inorganic chemistry
5.7E-34*(t/300.0)-2.8 O+O2+M $\rightarrow$ O3
9.6E-32*(t/300.0)-1.6 O+NO+M $\rightarrow$ NO2
2.0E-11*exp(100.0/t) OD+M $\rightarrow$ O
2.2E-10 OD+H2O $\rightarrow$ OH+OH
Immediate H+O2 $\rightarrow$ HO2
1.8E-12*exp(-1370./t) O3+NO $\rightarrow$ NO2
1.2E-13*exp(-2450./t) O3+NO2 $\rightarrow$ NO3
1.9E-12*exp(-1000./t) O3+OH $\rightarrow$ HO2
1.4E-14*exp(-600./t) O3+HO2 $\rightarrow$ OH
1.8E-11*exp(110./t) NO+NO3 $\rightarrow$ NO2+NO2
3.7E-12*exp(240./t) NO+HO2 $\rightarrow$ NO2+OH
7.2E-14*exp(-1414./t) NO2+NO3 $\rightarrow$ NO+NO2
1.4E-12 NO2+NO3 $\rightarrow$ N2O5
1.4E-11 NO2+OH $\rightarrow$ HNO3
4.1E-16 NO3+H2O2 $\rightarrow$ HO2+HNO3
7.1E+14*exp(-11080./t) N2O5 $\rightarrow$ NO2+NO3
4.8E-11*exp(250./t) OH+HO2 $\rightarrow$ H2O
2.9E-12*exp(-160./t) OH+H2O2 $\rightarrow$ HO2
7.7E-12*exp(-2100./t) OH+H2 $\rightarrow$ H
1.0E-14*exp(785./t) OH+HNO3 $\rightarrow$ NO3
FHO2*2.3E-13*exp(600./t) HO2+HO2 $\rightarrow$ H2O2
FHO2*M*1.7E-33*exp(1000./t) HO2+HO2 $\rightarrow$ H2O2
Sulphur chemistry
1.35E-12 OH+SO2 $\rightarrow$ HSO3
4.0E-17 CH3O2+SO2 $\rightarrow$ SO3+CH3O
Immediate HSO3+O2 $\rightarrow$ HO2+SO3
Immediate SO3+H2O $\rightarrow$ SA
Methane chemistry
7.44*10-18 x T2 x exp(-1361/T) OH+CH4 $\rightarrow$ CH3
Immediate CH3+O2 $\rightarrow$ CH3O2
KRO2NO CH3O2+NO $\rightarrow$ CH3O+NO2
5.5E-14*exp(365./t) CH3O2+CH3O2$\rightarrow$CH3O+CH3O
5.5E-14*exp(365./t) CH3O2+CH3O2$\rightarrow$CH3OH+HCHO
3.3E-12*exp(-380./t) OH+CH3OH$\rightarrow$HO2+HCHO
3.8E-13*exp(780./t) HO2+CH3O2 $\rightarrow$ CH3O2H
Immediate CH3O+O2 $\rightarrow$ HCHO+HO2
9.6E-12 OH+HCHO $\rightarrow$ HCO
Immediate HCO+O2 $\rightarrow$ CO+HO2
1.0E-12*exp(190./t) CH3O2H + OH $\rightarrow$ HCHO + OH
1.9E-12*exp(190./t) CH3O2H + OH $\rightarrow$ CH3O2
5.8E-16 NO3+HCHO $\rightarrow$ HNO3+HCO
2.4E-13 OH+CO $\rightarrow$ H
Ethane chemistry
7.8E-12*exp(-1020./t) OH+C2H6 $\rightarrow$ C2H5O2
8.9E-12 C2H5O2+NO $\rightarrow$ C2H5O+NO2
6.5E-13*exp(650./t) C2H5O2+HO2 $\rightarrow$ C2H5OOH
5.8E-12*exp(190./t) C2H5OOH+OH $\rightarrow$ CH3CHO+OH
1.9E-12*exp(190./t) C2H5OOH+OH $\rightarrow$ C2H5O2
Immediate C2H5O+O2 $\rightarrow$ HO2+CH3CHO
5.6E-12*exp(310./t) OH+CH3CHO $\rightarrow$ CH3COO2
1.0E-11 CH3COO2+NO2 $\rightarrow$ PAN
1.34E+16*exp(-13330./t) PAN $\rightarrow$ CH3COO2+NO2
2.0E-11 CH3COO2+NO $\rightarrow$ NO2+CH3
5.5E-12 CH3O2+CH3COO2 $\rightarrow$ CH3O+CH3
5.5E-12 CH3O2+CH3COO2 $\rightarrow$ CH3COOH+HCHO
2.8E-12*exp(530/t) CH3COO2+CH3COO2 $\rightarrow$ CH3+CH3
1.3E-13*exp(1040./t) CH3COO2+HO2 $\rightarrow$ CH3COO2H
1.9E-12*exp(190./t) CH3COO2H+OH $\rightarrow$ CH3COO2
3.0E-13*exp(1040./t) CH3COO2+HO2 $\rightarrow$ CH3COOH + O3
Ethanol chemistry
3.2E-12 OH+C2H5OH $\rightarrow$ CH3CHO + HO2
n-butane chemistry
1.64E-11*exp(-559./t) OH+NC4H10 $\rightarrow$ SECC4H9O2
KRO2NO NO+SECC4H9O2$\rightarrow$NO2+SECC4H9O
Immediate SECC4H9O$\rightarrow$ 0.65 HO2 + 0.65 CH3COC2H5 + 0.35 CH3CHO +0.35 C2H5O2
1.15E-12 OH+CH3COC2H5 $\rightarrow$ CH3COCHO2CH3
4.8E-12 CH3COCHO2HCH3+OH$\rightarrow$CH3COCHO2CH3
KHO2RO2 SECC4H9O2+HO2$\rightarrow$SECC4H9O2H
KRC92 SECC4H9O2H+OH$\rightarrow$SECC4H9O2
KRC91 SECC4H9O2H+OH$\rightarrow$OH+CH3COC2H5
Ethene chemistry
1.66E-12*exp(474./t) C2H4+OH $\rightarrow$ CH2O2CH2OH
KHO2RO2 CH2O2CH2OH+HO2 $\rightarrow$ CH2OOHCH2OH
KRC91 CH2OOHCH2OH+OH $\rightarrow$ CH3CHO + OH
KRC92 CH2OOHCH2OH+OH $\rightarrow$ CH2O2CH2OH
1.2E-14*exp(-2630./t) C2H4+O3$\rightarrow$HCHO+0.44 CO+ 0.12 HO2+ 0.4 HCOOH+ 0.13 H2
Propene chemistry
6.5E-15*exp(-1880./t) O3+C3H6$\rightarrow$ 0.5 HCHO+ 0.5 CH3CHO+ 0.07 CH4+ 0.4 CO+ 0.28 HO2+ 0.15 OH+ 0.31 CH3O2+ 0.07 H2
2.86E-11 OH+C3H6 $\rightarrow$ CH3CHO2CH2OH
KRC91 CH3CHOOHCH2OH+OH$\rightarrow$ CH3COC2H5+OH
o-xylene chemistry
1.37E-11 OXYL+OH$\rightarrow$OXYO2
KHO2RO2 OXYO2 + HO2$\rightarrow$OXYO2H
1.7E-11 OXYO2H + OH $\rightarrow$ OXYO2
2.0E-11 MAL+OH$\rightarrow$MALO2
KHO2RO2 MALO2+HO2$\rightarrow$MALO2H
2.4E-11 MALO2H+OH $\rightarrow$ MALO2
1.1E-11 OH+GLYOX$\rightarrow$HO2+CO+CO
1.70E-11 OH+MGLYOX$\rightarrow$CH3COO2+CO
Aerosol chemistry
RH dependent H2O2 $\rightarrow$ aerosol
RH dependent CH3O2H $\rightarrow$ aerosol
RH dependent N2O5 $\rightarrow$ 2 x nitrate
RH dependent HNO3 $\rightarrow$ nitrate
Isoprene chemistry
12.3E-15*exp(-2013/t) ISOP+O3$\rightarrow$ 0.67 MACR, 0.26 MVK+0.3 O, 0.55 OH+0.07 C3H6+0.8 HCHO+0.06 HO2+0.05 CO
2.54E-11*exp(410./t) ISOP+OH$\rightarrow$ISRO2
KRO2NO ISRO2+NO$\rightarrow$ 0.32 MACR+0.42 MVK+0.74 HCHO, 0.14 ISNI+0.12 ISRO2+0.78 HO2+0.86 NO2
4.13E-12*exp(452./t) MVK+OH$\rightarrow$MVKO2
KRO2NO MVKO2+NO$\rightarrow$ 0.684 CH3CHO+0.684 CH3COO2+ 0.266 MGLYOX+0.266 HCHO+0.05 ISNI+0.95 NO2+0.95 HO2
KHO2RO2 ISRO2+HO2$\rightarrow$ISRO2H
2.0E-11 ISRO2H + OH$\rightarrow$OH+ISRO2
8.0E-18 ISRO2H + O3$\rightarrow$*0.7:HCHO
1.86E-11*exp(175./t) MACR+OH$\rightarrow$0.5 AOH1+ 0.5:MACRO2
1.0E-11 MACRO2+NO2$\rightarrow$MPAN
1.34E+16*exp(-13330./t) MPAN $\rightarrow$ MACRO2+NO2
2.0E-11 MACRO2+NO$\rightarrow$CH2CCH3+NO2
KRO2NO CH2CCH3+NO $\rightarrow$NO2+CH3COC2H5+HO2
4.32E-15*exp(-2016./t) MVK+O3$\rightarrow$0.82 MGLYOX+0.8 HCHO+0.2 O+ 0.05 CO+0.06 HO2+0.04 CH3CHO+0.08 OH
3.35E-11 ISNI+OH$\rightarrow$ISNIR
KRO2NO ISNIR+NO$\rightarrow$ 0.05 HO2+ 2.0 NO2+ 0.95 CH3CHO+ 0.95 CH3COC2H5
NO3 chemistry  
7.8E-13 ISOP +NO3$\rightarrow$ISONO3
KRO2NO ISONO3+NO$\rightarrow$1.1 NO2+0.8 HO2+0.85 ISNI+0.1 MACR+0.15 HCHO+0.05 MVK
Extra since Note 2/93 (Simpson et al. 1993)
KHO2RO2 MVKO2 + HO2 $\rightarrow$ MVKO2H
KHO2RO2 MACRO2 + HO2 $\rightarrow$ MARO2H
KHO2RO2 CH2CCH3+ HO2 $\rightarrow$ CH2CO2HCH3
KHO2RO2 ISNIR + HO2 $\rightarrow$ ISNIRH
KHO2RO2 ISONO3 + HO2 $\rightarrow$ ISONO3H
3.2E-11 CH2CO2HCH3 + OH $\rightarrow$ CH2CCH3
2.0E-11 ISONO3H + OH $\rightarrow$ ISONO3
2.2E-11 MVKO2H + OH $\rightarrow$ MVKO2
3.7E-11 ISNIRH + OH $\rightarrow$ ISNIR
3.7E-11 MARO2H + OH $\rightarrow$ MACRO2

Abbreviations for some species names:

OXYO2 Peroxy radical from o-xylene + OH
OXYO2H Hydroperoxide from OXYO2 + HO2
MGLYOX Methyl-glyoxal (CH3COCHO)
MALO2 Peroxy radical from MAL + OH
MALO2H Hydroperoxide from MALO2 + HO2
ISRO2 Peroxy radical from isoprene + OH
ISRO2H Hydroperoxide from ISRO2 + HO2
MACR Methacrolein
MACRO2 Hydroperoxide from Methacrolein
MPAN Peroxy methacryloyl nitrate (CH2CH(CH3)C(=O)O2NO2)
MVK Methyl-vinyl-ketone
MVKO2 Peroxy radical from MVK + OH
MVKO2H Hydroperoxide from MVKO2 + HO2
ISNI Organic nitrate from isoprene
ISONO3 Isoprene-NO3 adduct
ISNIR Alkyl peroxy radical from ISNI

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David Simpson