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2NaI + 2H2O 💧⚡→ 2NaOH + I2 + H2

Electrolysis of aqueous sodium iodide with water as oxidizing agent

Electrolysis of aqueous sodium iodide yields sodium hydroxide, iodine, and hydrogen (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

Electrolysis of aqueous sodium iodide with water as oxidizing agent

General equation

Electrolysis of aqueous solution with water as oxidizing agent
Miscible with water/Very soluble in water/Soluble in waterReducing agent + H2OOxidizing agent
💧⚡
ProductOxidation product + ProductReduction product

Oxidation state of each atom

Electrolysis of aqueous sodium iodide with water as oxidizing agent

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
NaISodium iodide2
Reducing
Very soluble in water
H2OWater2
Oxidizing
Water

Products

Chemical formulaNameCoefficientTypeType in general
equation
NaOHSodium hydroxide2
I2Iodine1
Oxidized
H2Hydrogen1
Reduced

Thermodynamic changes

Changes in standard condition

Electrolysis of aqueous sodium iodide with water as oxidizing agent
ΔrG287.39 kJ/mol
K0.45 × 10−50
pK50.35
2NaICrystalline solid + 2H2OLiquid
💧⚡
2NaOHCrystalline solid + I2Crystalline solid + H2Gas
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
296.00287.3938.85−52.42
per 1 mol of
148.00143.6919.43−26.21
per 1 mol of
148.00143.6919.43−26.21
per 1 mol of
148.00143.6919.43−26.21
per 1 mol of
296.00287.3938.85−52.42
per 1 mol of
296.00287.3938.85−52.42

Changes in aqueous solution (1)

Electrolysis of aqueous sodium iodide with water as oxidizing agent
ΔrG279.30 kJ/mol
K0.12 × 10−48
pK48.93
2NaIIonized aqueous solution + 2H2OLiquid
💧⚡
2NaOHIonized aqueous solution + I2Un-ionized aqueous solution + H2Gas
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
244.7279.30−116.3
per 1 mol of
122.3139.65−58.15
per 1 mol of
122.3139.65−58.15
per 1 mol of
122.3139.65−58.15
per 1 mol of
244.7279.30−116.3
per 1 mol of
244.7279.30−116.3

Changes in aqueous solution (2)

Electrolysis of aqueous sodium iodide with water as oxidizing agent
ΔrG296.9 kJ/mol
K0.97 × 10−52
pK52.01
2NaIIonized aqueous solution + 2H2OLiquid
💧⚡
2NaOHIonized aqueous solution + I2Un-ionized aqueous solution + H2Un-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
240.5296.9330
per 1 mol of
120.3148.4165
per 1 mol of
120.3148.4165
per 1 mol of
120.3148.4165
per 1 mol of
240.5296.9330
per 1 mol of
240.5296.9330

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
NaI (cr)-287.78[1]-286.06[1]98.53[1]52.09[1]
NaI (g)-79.5[1]-121.0[1]248.978[1]36.65[1]
NaI (ai)-295.31[1]-313.47[1]170.3[1]-95.8[1]
NaI (cr)
1 hydrate
-883.096[1]-771.10[1]196.2[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]
* (cr):Crystalline solid, (g):Gas, (ai):Ionized aqueous solution, (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
NaOH (cr)-425.609[1]-379.494[1]64.455[1]59.54[1]
NaOH (g)-207.1[1]-210.0[1]228.43[1]48.37[1]
NaOH (ai)-470.114[1]-419.150[1]48.1[1]-102.1[1]
NaOH (cr)
1 hydrate
-734.543[1]-629.338[1]99.50[1]90.17[1]
NaOH (l)
2 hydrate
-1019.076[1]-873.091[1]195.979[1]239.41[1]
NaOH (l)
3.5 hydrate
-1459.798[1]-1236.356[1]286.089[1]354.43[1]
NaOH (l)
4 hydrate
-1605.15[1]-1356.64[1]318.70[1]
NaOH (l)
5 hydrate
-1894.31[1]-1596.34[1]386.06[1]
NaOH (l)
7 hydrate
-2469.02[1]-2073.80[1]526.31[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]
H2 (g)0[1]0[1]130.684[1]28.824[1]
H2 (ao)-4.2[1]17.6[1]577[1]
* (cr):Crystalline solid, (g):Gas, (ai):Ionized aqueous solution, (l):Liquid, (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)