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2KI + Cl2 → 2KCl + I2

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Reaction of potassium iodide and chlorine
2KIPotassium iodide + Cl2Chlorine
⟶
2KClPotassium chloride + I2Iodine

The reaction of potassium iodide and chlorine yields potassium chloride and iodine. 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 categories

Reaction data

Chemical equation

Reaction of potassium iodide and chlorine
2KIPotassium iodide + Cl2Chlorine
⟶
2KClPotassium chloride + I2Iodine

General equation

Reaction of oxidizable species and oxidizing species
Oxidizable speciesReducing agent + Oxidizing speciesOxidizing agent
⟶
ProductOxidation product + ProductReduction product

Oxidation state of each atom

Reaction of potassium iodide and chlorine

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
KIPotassium iodide2
Reducing
Oxidizable
Cl2Chlorine1
Oxidizing
Oxidizing

Products

Chemical formulaNameCoefficientTypeType in general
equation
KClPotassium chloride2
Reduced
–
I2Iodine1
Oxidized
–

Thermodynamic changes

Changes in standard condition

Reaction of potassium iodide and chlorine
◆
ΔrG−168.50 kJ/mol
K3.31 × 1029
pK−29.52
2KICrystalline solid + Cl2Gas
⟶
2KClCrystalline solid + I2Crystalline solid
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
−217.694−168.50−154.3917.27
per 1 mol of
−108.847−84.250−77.1958.635
per 1 mol of
−217.694−168.50−154.3917.27
per 1 mol of
−108.847−84.250−77.1958.635
per 1 mol of
−217.694−168.50−154.3917.27

Changes in aqueous solution

Reaction of potassium iodide and chlorine
◆
ΔrG−149.82 kJ/mol
K1.77 × 1026
pK−26.25
2KIIonized aqueous solution + Cl2Un-ionized aqueous solution
⟶
2KClIonized aqueous solution + I2Un-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
−177.9−149.82−93–
per 1 mol of
−88.95−74.910−47–
per 1 mol of
−177.9−149.82−93–
per 1 mol of
−88.95−74.910−47–
per 1 mol of
−177.9−149.82−93–

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]
Cl2 (g)0[1]0[1]223.066[1]33.907[1]
Cl2 (ao)-23.4[1]6.94[1]121[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
KCl (cr)-436.747[1]-409.14[1]82.59[1]51.30[1]
KCl (g)-214.14[1]-233.0[1]239.10[1]36.48[1]
KCl (ai)-419.53[1]-414.49[1]159.0[1]-114.6[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]–
* (cr):Crystalline solid, (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)