IUPAC Subcommittee on Gas Kinetic Data Evaluation

Providing evaluated kinetic data on the web since 1999.

IUPAC Subcommittee on Gas Kinetic Data Evaluation

Website: http://www.iupac-kinetic.ch.cam.ac.uk/ See website for latest evaluated data. Datasheets can be downloaded for personal use only and must not be retransmitted or disseminated either electronically or in hardcopy without explicit written permission.

This datasheet last evaluated: 2005-07-21 ; last change in preferred values: 2005-07-21 ; last peer-reviewed publication: 2006-09-06


HO + C2H2 + MC2H2OH + M(1) Δ Hο = -145 kJ mol-1

Rate Coefficient Data: Low-pressure rate coefficients

Absolute Rate Coefficients

Rate Coefficient (k0) / Temperature / ReferenceTechniques and Comments
cm3molecule-1s-1Kelvin
(3±1) × 10 -30 (T/300) 1.0 [Ar]297–429Perry and Williamson, 1982FP-RF (a)
(6±3) × 10 -30 [He]298Hack et al., 1983DF-EPR (b)
(2.5±0.3) × 10 -30 [Ar]295Schmidt et al., 1985PLP-LIF (c)
5 × 10 -30 [N 2 ]298Wahner and Zetzsch, 1985PLP-A (d)
(4.1±1.6) × 10 -30 [N 2 ]298Bohn et al., 1996PLP-A (e)
4.3 × 10 -29 (T/300) -3.1 exp (-910/T)[He]300–814Fulle et al., 1997PLP-LIF (f)
2.1 × 10 -30 [He]298

Absolute Rate Coefficients

Rate Coefficient (k0) / Temperature / ReferenceTechniques and Comments
cm3molecule-1s-1Kelvin
(2.92±0.55) × 10 -30 [air]296Sørenson et al., 2003RR (g)

Comments

(a) Photolysis of H 2 O-C 2 H 2 mixtures at 26-530 mbar Ar diluent. Pressure dependence observed is in agreement with earlier work (Perry et al., 1977; Michael et al., 1980). Evaluation of the falloff curve with F c =0.5.

(b) Pressures of 2.0-2.6 mbar were used. By the use of data from Perry and Williamson (1982) and F c =0.5, a falloff analysis of the measured k leads to the given k 0 value.

(c) Experiments in He, Ar and N 2 at pressures between 1 mbar and 1000 mbar (in Ar). Construction of falloff curve with F c =0.6 leads to k =(8.3±0.8) × 10 -13 cm 3 molecule -1 s -1 .

(d) Experiments in N 2 over the range 20 mbar to 1000 mbar. Falloff curve constructed with F c =0.6 leading to k =9×10 -13 cm 3 molecule -1 s -1 .

(e) Experiments with M=N 2 , O 2 and synthetic air at pressures from 15 mbar to 1 bar. Falloff extrapolation with F c =0.6. Effective rate coefficients for HO radical removal in O 2 and synthetic air were markedly lower than in N 2 due to HO radical regeneration by the reaction C 2 H 2 OH+O 2 HO + products, which shows evidence for an influence of the extent of vibrational de-excitation of C 2 H 2 OH.

(f) Pressure range 2 mbar to 130 bar of He. Combined with the data of (Schmidt et al., 1985), falloff curves were constructed using a calculated F c = [0.17 exp(-51/T) + exp(-T/204)], i.e., F c (298 K) = 0.37. From a third-law analysis of the equilibrium constant, the value ΔH (0 K) = -(146±10) kJ mol -1 was derived. The equilibrium constant obtained at temperatures above 700 K is given by K c =5.4×10 -2 T -1.7 exp(17 560/T) bar -1 .

(g) HO radicals were generated by the photolysis of CH 3 ONO in air. The concentrations of C 2 H 2 and dimethyl ether or propane (the reference compounds) were monitored by in situ FTIR spectroscopy or GC-FID, respectively. The measured rate coefficient ratios k(HO + C 2 H2)/k(HO + dimethyl ether) and k(HO + C 2 H 2 )/k(HO + propane) were placed on an absolute basis using rate coefficients of k(HO + dimethyl ether) = 2.98 × 10 -12 cm 3 molecule -1 s -1 and k(HO + propane) = 1.11 × 10 -12 cm 3 molecule -1 s -1 (Sørensen et al., 2003). Experiments were carried out over the pressure range 25–750 Torr (33–1000 mbar) of air or O 2 with analysis by FTIR spectroscopy and dimethyl ether as the reference compound, and over the pressure range 25–7905 Torr (33 mbar to 10.5 bar) of O 2 –N 2 diluent, with propane as the reference organic. Falloff curve was constructed with F c =0.6. Use of F c =0.4 led to k 0 = (7.00 ± 1.30) × 10 -30 [air] cm 3 molecule -1 s -1 and k = (1.06 ± 0.034) × 10 -12 cm 3 molecule -1 s -1 .

Preferred Values

k0cm3molecule-1s-1{5.1-30 N_2[N2] 5.1×10-30±0.1 N_2[N2]   if   T 298 5-30 T 300 PlusMinus -1.5 1.5 N_2[N2]5×10-30 (T/ 300 )( -1.5 ±1.5) N_2[N2]  if   298 T 800

Comments on Preferred Values

The preferred rate coefficient at 298 K is based on the experimental data of Schmidt et al. (1985), Wahner and Zetzsch (1985) and Bohn et al. (1996) and the theoretical analysis of Smith et al. (1984). The temperature dependence is based on the data of Perry et al. (1977), Michael et al. (1980) and Perry and Williamson (1982) as discussed and evaluated by Atkinson (1989). At temperatures above 500 K another component of the rate coefficient with a much stronger temperature dependence also has to be taken into account (Atkinson, 1989). The preferred values should be used in connection with the calculated F c values from Fulle et al. (1997) such as given in comment (f) of k 0 (F c = 0.37 at 298 K).

A comparison of the data of Perry et al. (1977), Michael et al. (1980), Perry and Williamson (1982), Hack et al. (1983), Atkinson and Aschmann (1984), Schmidt et al. (1985), Wahner and Zetzsch (1985), Hatakeyama et al. (1986), Liu et al. (1988), Arnts et al. (1989) and Bohn et al. (1996) at pressures between 0.01–1 bar with the results from Fulle et al. (1997) at 2–80 bar shows considerable discrepancies, with the data of Fulle et al. (1997) leading to k considerably higher than the lower pressure data. This influences the construction of falloff curves and the extrapolation to k 0 . The recent study of Sørensen et al. (2003) confirms the earlier data of Perry et al. (1977), Michael et al. (1980), Perry and Williamson (1982), Hack et al. (1983), Atkinson and Aschmann (1984), Schmidt et al. (1985), Wahner and Zetzsch (1985), Hatakeyama et al. (1986), Liu et al. (1988), Arnts et al. (1989) and Bohn et al. (1996) [see below].

Rate Coefficient Data: High-pressure rate coefficients

Absolute Rate Coefficients

Rate Coefficient (k) / Temperature / ReferenceTechniques and Comments
cm3molecule-1s-1Kelvin
(6.91±0.90) × 10 -13 297Perry and Williamson, 1982FP-RF (a)
(8.3±0.8) × 10 -13 295Schmidt et al., 1985PLP-LIF (b)
9 × 10 -13 298Wahner and Zetzsch, 1985PLP-A (c)
(8.5±0.6) × 10 -13 298Bohn et al., 1996PLP-A (d)
8.5 × 10 -12 exp(-705/T)333–1273Liu et al., 1988PR-RA (e)
8.0 × 10 -13 298*
3.8 × 10 -11 exp(-910/T)300–814Fulle et al., 1997PLP-LIF (f)
1.8 × 10 -12 298*

Relative Rate Coefficients

Rate Coefficient (k) / Temperature / ReferenceTechniques and Comments
cm3molecule-1s-1Kelvin
(8.1±1.3) × 10 -13 (1 bar air)298Atkinson and Aschmann, 1984RR (g)
(8.1±1.8) × 10 -13 (1 bar air)297±2Hatakeyama et al., 1986RR (h)
(7.0±0.7) × 10 -13 (1 bar air)297 ± 2Arnts et al., 1989RR (i)
(9.69±0.30) × 10 -13 296Sørensen et al., 2003RR (j)
(7.67±0.06) × 10 -13 (1 bar air)296Sørensen et al., 2003RR
(8.2±1.0) × 10 -13 (1 bar N 2 -O 2 )296Sørensen et al., 2003RR

Comments

(a) See comment (a) for k 0 .

(b) See comment (c) for k 0 .

(c) See comment (d) for k 0 .

(d) See comment (e) for k 0 .

(e) Measurements were conducted at 1 bar of Ar.

(f) See comment (e) for k 0 .

(g) HO radicals were generated by the photolysis of CH 3 ONO in CH 3 ONO-NO-C 2 H 2 -cyclohexane-air mixtures at 1 bar total pressure. The concentrations of acetylene and cyclohexane (the reference compound) were measured by GC. The measured rate coefficient ratio is placed on an absolute basis by use of a rate coefficient of k(HO + cyclohexane)=6.97×10 -12 cm 3 molecule -1 s -1 (Atkinson, 1997).

(h) HO radicals were generated by photolysis of H 2 O 2 in air at 254 nm. The concentrations of acetylene and cyclohexane (the reference compound) were monitored by FTIR spectrometry. Measurements were carried out at 1 bar pressure in air. The measured rate coefficient ratio k(HO+C 2 H 2 )/k(HO + cyclohexane) = 0.116±0.025 is placed on an absolute basis by use of a rate coefficient of k(HO + cyclohexane)=6.95 ×10 -12 cm 3 molecule -1 s -1 (Atkinson, 2003).

(i) HO radicals were generated by the photolysis of CH 3 ONO in air at 1 bar pressure. The concentrations of acetylene and ethane (the reference compound) were measured by GC. The measured rate coefficient ratio of k(HO+C 2 H 2 )/k(HO + ethane) = 2.84±0.26 (two standard deviations) is placed on an absolute basis by use of a rate coefficient of k(HO + ethane) = 2.45×10 -13 cm 3 molecule -1 s -1 (IUPAC, 2005).

(j) See comment (g) for k 0 .

(k) HO radicals were generated by the photolysis of CH 3 ONO in air at 928–1013 mbar of O 2 -N 2 diluent. The concentrations of C 2 H 2 and dimethyl ether or propane (the reference compounds) were monitored by in situ FTIR spectroscopy or GC-FID, respectively. The measured rate coefficient ratios k(HO + C 2 H 2 )/k(HO + dimethyl ether) = 0.276 ± 0.021 and k(HO + C 2 H 2 )/k(HO + propane) = 0.761 ± 0.09 were placed on an absolute basis using rate coefficients of k(HO + dimethyl ether) = 2.78 ×10 -12 cm 3 molecule -1 s -1 (IUPAC, 2005) and k(HO + propane) = 1.08 ×10 -12 cm 3 molecule -1 s -1 (IUPAC, 2005).

(l) Relative to dimethyl ether.

(m) Relative to propane.

Preferred Values

kcm3molecule-1s-17.8-137.8×10-13±0.15  if   T 298   and   P 1 bar of air kcm3molecule-1s-11.0-121.0×10-12±0.3  if   T 298

Comments on Preferred Values

The recent study of Sørensen et al. (2003) confirms the earlier data of Perry et al. (1977), Michael et al. (1980), Perry and Williamson (1982), Atkinson and Aschmann (1984), Schmidt et al. (1985), Wahner and Zetzsch (1985), Hatakeyama et al. (1986), Liu et al. (1988), Arnts et al. (1989) and Bohn et al. (1996), all of which indicate a rate coefficient at room temperature and 1 bar of air or N 2 of 8 ×10 -13 cm 3 molecule -1 s -1 and a value of k 1.0 ×10 -12 cm 3 molecule -1 s -1 at 298 K. These data are, however, inconsistent with those from the study of Fulle et al. (1997), for reasons which are presently not understood (at 298 K and 1 bar of He, the data of Fulle et al. (1997) lead to k = 1.12 ×10 -12 cm 3 molecule -1 s -1 , with k = 1.8 ×10 -12 cm 3 molecule -1 s -1 at 298 K).

The preferred values are based on the data of Perry and Williamson (1982), Atkinson and Aschmann (1984), Schmidt et al. (1985), Wahner and Zetzsch (1985), Hatakeyama et al. (1986), Liu et al. (1988), Arnts et al. (1989), Bohn et al. (1996) and Sørensen et al. (2003) and are applicable to room temperature only.

References

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