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4NH4I + 7O2 → 4HNO2 + 2I2 + 6H2O

The reaction of ammonium iodide and oxygen yields nitrous acid, iodine, and water (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 reducing species and oxidizing species
Reducing speciesReducing agent + Oxidizing speciesOxidizing agent
ProductOxidation product + ProductReduction product

Oxidation state of each atom

Reaction of ammonium iodide and oxygen

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
NH4IAmmonium iodide4
Reducing
Reducing
O2Oxygen7
Oxidizing
Oxidizing

Products

Chemical formulaNameCoefficientTypeType in general
equation
HNO2Nitrous acid4
Redoxed product
I2Iodine2
Oxidized
H2OWater6
Reduced

Thermodynamic changes

Changes in standard condition

Reaction of ammonium iodide and oxygen
ΔrG−1183.7 kJ/mol
K2.37 × 10207
pK−207.38
4NH4IIonized aqueous solution + 7O2Un-ionized aqueous solution
4HNO2Un-ionized aqueous solution + 2I2Un-ionized aqueous solution + 6H2OLiquid
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
−1313.9−1183.7−438.8
per 1 mol of
−328.48−295.93−109.7
per 1 mol of
−187.70−169.10−62.69
per 1 mol of
−328.48−295.93−109.7
per 1 mol of
−656.95−591.85−219.4
per 1 mol of
−218.98−197.28−73.13

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
NH4I (cr)-201.42[1]-112.5[1]117[1]
NH4I (ai)-187.69[1]-130.88[1]224.7[1]-62.3[1]
O2 (g)0[1]0[1]205.138[1]29.355[1]
O2 (ao)-11.7[1]16.4[1]110.9[1]
* (cr):Crystalline solid, (ai):Ionized aqueous solution, (g):Gas, (ao):Un-ionized aqueous solution

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
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]
I2 (cr)0[1]0[1]116.135[1]54.438[1]
I2 (g)62.438[1]19.327[1]260.69[1]36.90[1]
I2 (ao)22.6[1]16.40[1]137.2[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, (ao):Un-ionized aqueous solution, (cr):Crystalline solid, (l):Liquid

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)