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2NO2 + H2O → HNO3 + HNO2

The reaction of nitrogen dioxide and water yields nitric acid and nitrous acid (Other reactions are here). This reaction is an oxidation-reduction reaction and is classified as follows:

Table of contents
  1. 1Reaction data
  2. 2Thermodynamic changes
  3. 3References
  4. 4Related reactions
  5. 5Related categories

Reaction data

Chemical equation

General equation

Reaction of self redoxing species and water
Self-redoxing speciesSelf redox agent + H2ONon-redox agent
ProductOxidation product + ProductReduction product

Oxidation state of each atom

Reaction of nitrogen dioxide and water

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
NO2Nitrogen dioxide2
Self redoxing
H2OWater1
Water

Products

Chemical formulaNameCoefficientTypeType in general
equation
HNO3Nitric acid1
Oxidized
HNO2Nitrous acid1
Reduced

Thermodynamic changes

Changes in standard condition

Reaction of nitrogen dioxide and water
ΔrG−27.3 kJ/mol
K6.06 × 104
pK−4.78
2NO2Gas + H2OLiquid
HNO3Ionized aqueous solution + HNO2Un-ionized aqueous solution
Standard enthalpy
of reaction
ΔrH°
kJ · mol−1
Standard
Gibbs energy
of reaction
ΔrG°
kJ · mol−1
Standard entropy
of reaction
ΔrS°
J · K−1 · mol−1
Standard heat
capacity of reaction
at constant pressure
ΔrCp°
J · K−1 · mol−1
per 1 mol of
Equation
−107.1−27.3−268.0
per 1 mol of
−53.55−13.7−134.0
per 1 mol of
−107.1−27.3−268.0
per 1 mol of
−107.1−27.3−268.0
per 1 mol of
−107.1−27.3−268.0

Thermodynamic data of reactants

Chemical formulaStandard enthalpy
of formation
ΔfH°
kJ · mol−1
Standard Gibbs
energy of
formation
ΔfG°
kJ · mol−1
Standard
molar entropy
S°
J · K−1 · mol−1
Standard molar
heat capacity at
constant pressure
Cp°
J · K−1 · mol−1
NO2 (g)33.18[1]51.31[1]240.06[1]37.20[1]
H2O (cr)
H2O (l)-285.830[1]-237.129[1]69.91[1]75.291[1]
H2O (g)-241.818[1]-228.572[1]188.825[1]33.577[1]
* (g):Gas, (cr):Crystalline solid, (l):Liquid

Thermodynamic data of products

Chemical formulaStandard enthalpy
of formation
ΔfH°
kJ · mol−1
Standard Gibbs
energy of
formation
ΔfG°
kJ · mol−1
Standard
molar entropy
S°
J · K−1 · mol−1
Standard molar
heat capacity at
constant pressure
Cp°
J · K−1 · mol−1
HNO3 (l)-174.10[1]-80.71[1]155.60[1]109.87[1]
HNO3 (g)-135.06[1]-74.72[1]266.38[1]53.35[1]
HNO3 (ai)-207.36[1]-111.25[1]146.4[1]-86.6[1]
HNO3 (l)
1 hydrate
-473.46[1]-328.77[1]216.90[1]182.46[1]
HNO3 (l)
3 hydrate
-1056.04[1]-811.09[1]346.98[1]325.14[1]
HNO2 (g)
cis
-77.99[1]-42.94[1]248.76[1]44.77[1]
HNO2 (g)
trans
-80.12[1]-45.24[1]249.22[1]46.07[1]
HNO2 (g)-79.5[1]-46.0[1]254.1[1]45.6[1]
HNO2 (ao)-119.2[1]-50.6[1]135.6[1]
* (l):Liquid, (g):Gas, (ai):Ionized aqueous solution, (ao):Un-ionized aqueous solution

References

List of references

  1. 1
    Janiel J. Reed (1989)
    The NBS Tables of Chemical Thermodynamic Properties: Selected Values for Inorganic and C1 and C2 Organic Substances in SI Units
    National Institute of Standards and Technology (NIST)