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4KI + 2HClO2 + 4H+ → 4K+ + 2I2 + Cl2O↑ + 3H2O

Reaction of potassium iodide and chlorous acid under acidic condition
4KIPotassium iodide + 2HClO2Chlorous acid + 4H+Hydrogen ion
4K+Potassium ion + 2I2Iodine + Cl2ODichlorine monoxide + 3H2OWater

The reaction of potassium iodide, chlorous acid, and hydrogen ion yields potassium ion, iodine, dichlorine monoxide, 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

Reaction of potassium iodide and chlorous acid under acidic condition
4KIPotassium iodide + 2HClO2Chlorous acid + 4H+Hydrogen ion
4K+Potassium ion + 2I2Iodine + Cl2ODichlorine monoxide + 3H2OWater

General equation

Reaction of oxidizable species and oxidizing species under acidic condition
Oxidizable speciesReducing agent + Oxidizing speciesOxidizing agent + H+Non-redox agent
ProductOxidation product + ProductReduction product + H2ONon-redox product

Oxidation state of each atom

Reaction of potassium iodide and chlorous acid under acidic condition

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
KIPotassium iodide4
Reducing
Oxidizable
HClO2Chlorous acid2
Oxidizing
Oxidizing under acidic condition
H+Hydrogen ion4
Hydrogen ion

Products

Chemical formulaNameCoefficientTypeType in general
equation
K+Potassium ion4
I2Iodine2
Oxidized
Cl2ODichlorine monoxide1
Reduced
H2OWater3
Water

Thermodynamic changes

Changes in standard condition

Reaction of potassium iodide and chlorous acid under acidic condition
ΔrG−386.2 kJ/mol
K4.56 × 1067
pK−67.66
4KIIonized aqueous solution + 2HClO2Un-ionized aqueous solution + 4H+Un-ionized aqueous solution
4K+Un-ionized aqueous solution + 2I2Un-ionized aqueous solution + Cl2OGas + 3H2OLiquid
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
−407.4−386.2−71.5
per 1 mol of
−101.8−96.55−17.9
per 1 mol of
−203.7−193.1−35.8
per 1 mol of
Hydrogen ion
−101.8−96.55−17.9
per 1 mol of
Potassium ion
−101.8−96.55−17.9
per 1 mol of
−203.7−193.1−35.8
−407.4−386.2−71.5
per 1 mol of
−135.8−128.7−23.8

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
KI (cr)-327.900[1]-324.892[1]106.32[1]52.93[1]
KI (g)-125.5[1]-166.1[1]258.3[1]37.11[1]
KI (ai)-307.57[1]-334.85[1]213.8[1]-120.5[1]
HClO2 (ao)-51.9[1]5.9[1]188.3[1]
H+ (g)1536.202[1]
H+ (ao)0[1]0[1]0[1]0[1]
* (cr):Crystalline solid, (g):Gas, (ai):Ionized aqueous solution, (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
K+ (g)514.26[1]
K+ (ao)-252.38[1]-283.27[1]102.5[1]21.8[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]
Cl2O (g)80.3[1]97.9[1]266.21[1]45.40[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)