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Na2SO3 + H3PO4 🔥→ Na2HPO4 + SO2↑ + H2O

The reaction of sodium sulfite and phosphoric acid yields sodium hydrogenphosphate, sulfur dioxide, and water (Other reactions are here). This reaction is an acid-base 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

Oxidation state of each atom

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
Na2SO3Sodium sulfite1
Brønsted base
Salt of volatile acid
H3PO4Phosphoric acid1
Brønsted acid
Nonvolatile acid

Products

Chemical formulaNameCoefficientTypeType in general
equation
Na2HPO4Sodium hydrogenphosphate1
Conjugate base
Salt of non volatile acid
SO2Sulfur dioxide1
Volatile acidic oxide
H2OWater1
Conjugate acid
Water

Thermodynamic changes

Changes in standard condition

Reaction of sodium sulfite and phosphoric acid
ΔrG−13.9 kJ/mol
K2.72 × 102
pK−2.44
Na2SO3Crystalline solid + H3PO4Crystalline solid
🔥
Na2HPO4Crystalline solid + SO2Gas + H2OLiquid
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
49.0−13.9212.1924.16
per 1 mol of
49.0−13.9212.1924.16
per 1 mol of
49.0−13.9212.1924.16
49.0−13.9212.1924.16
per 1 mol of
49.0−13.9212.1924.16
per 1 mol of
49.0−13.9212.1924.16

Changes in aqueous solution (1)

Reaction of sodium sulfite and phosphoric acid
ΔrG2.63 kJ/mol
K0.35 × 100
pK0.46
Na2SO3Ionized aqueous solution + H3PO4Un-ionized aqueous solution
🔥
Na2HPO4Ionized aqueous solution + SO2Gas + H2OLiquid
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
49.172.63156.5
per 1 mol of
49.172.63156.5
per 1 mol of
49.172.63156.5
49.172.63156.5
per 1 mol of
49.172.63156.5
per 1 mol of
49.172.63156.5

Changes in aqueous solution (2)

Reaction of sodium sulfite and phosphoric acid
ΔrG2.14 kJ/mol
K0.42 × 100
pK0.37
Na2SO3Ionized aqueous solution + H3PO4Un-ionized aqueous solution
🔥
Na2HPO4Ionized aqueous solution + SO2Un-ionized aqueous solution + H2OLiquid
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
23.022.1470.2
per 1 mol of
23.022.1470.2
per 1 mol of
23.022.1470.2
23.022.1470.2
per 1 mol of
23.022.1470.2
per 1 mol of
23.022.1470.2

Changes in aqueous solution (3)

Reaction of sodium sulfite and phosphoric acid
ΔrG−121.2 kJ/mol
K1.71 × 1021
pK−21.23
Na2SO3Ionized aqueous solution + H3PO4Ionized aqueous solution
🔥
Na2HPO4Ionized aqueous solution + SO2Gas + H2OLiquid
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
38.2−121.2535.0
per 1 mol of
38.2−121.2535.0
per 1 mol of
38.2−121.2535.0
38.2−121.2535.0
per 1 mol of
38.2−121.2535.0
per 1 mol of
38.2−121.2535.0

Changes in aqueous solution (4)

Reaction of sodium sulfite and phosphoric acid
ΔrG−121.7 kJ/mol
K2.09 × 1021
pK−21.32
Na2SO3Ionized aqueous solution + H3PO4Ionized aqueous solution
🔥
Na2HPO4Ionized aqueous solution + SO2Un-ionized aqueous solution + H2OLiquid
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
12.1−121.7448.7
per 1 mol of
12.1−121.7448.7
per 1 mol of
12.1−121.7448.7
12.1−121.7448.7
per 1 mol of
12.1−121.7448.7
per 1 mol of
12.1−121.7448.7

Changes in aqueous solution (5)

Reaction of sodium sulfite and phosphoric acid
ΔrG2.63 kJ/mol
K0.35 × 100
pK0.46
Na2SO3Ionized aqueous solution + H3PO4Un-ionized aqueous solution
🔥
Na2HPO4Ionized aqueous solution + SO2Gas + H2OLiquid
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
49.172.63156.5
per 1 mol of
49.172.63156.5
per 1 mol of
49.172.63156.5
49.172.63156.5
per 1 mol of
49.172.63156.5
per 1 mol of
49.172.63156.5

Changes in aqueous solution (6)

Reaction of sodium sulfite and phosphoric acid
ΔrG2.14 kJ/mol
K0.42 × 100
pK0.37
Na2SO3Ionized aqueous solution + H3PO4Un-ionized aqueous solution
🔥
Na2HPO4Ionized aqueous solution + SO2Un-ionized aqueous solution + H2OLiquid
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
23.022.1470.2
per 1 mol of
23.022.1470.2
per 1 mol of
23.022.1470.2
23.022.1470.2
per 1 mol of
23.022.1470.2
per 1 mol of
23.022.1470.2

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
Na2SO3 (cr)-1100.8[1]-1012.5[1]145.94[1]120.25[1]
Na2SO3 (ai)-1115.87[1]-1010.39[1]87.9[1]
Na2SO3 (cr)
7 hydrate
-3162.3[1]-2676.1[1]444[1]
H3PO4 (cr)-1279.0[1]-1119.1[1]110.50[1]106.06[1]
H3PO4 (l)-1266.9[1]
H3PO4 (ai)-1277.4[1]-1018.7[1]-220.3[1]
H3PO4 (ao)-1288.34[1]-1142.54[1]158.2[1]
H3PO4 (cr)
0.5 hydrate
-1431.3[1]-1242.1[1]129.16[1]126.02[1]
H3PO4 (cr)
1 hydrate
-1568.83[1]
* (cr):Crystalline solid, (ai):Ionized aqueous solution, (l):Liquid, (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
Na2HPO4 (cr)-1748.1[1]-1608.2[1]150.50[1]135.31[1]
Na2HPO4 (ai)-1772.38[1]-1612.98[1]84.5[1]
Na2HPO4 (cr)
2 hydrate
-2346.0[1]-2088.5[1]221.3[1]
Na2HPO4 (cr)
7 hydrate
-3821.7[1]-3279.8[1]434.59[1]
Na2HPO4 (cr)
12 hydrate
-5297.8[1]-4467.8[1]633.83[1]
SO2 (l)-320.5[1]
SO2 (g)-296.830[1]-300.194[1]248.22[1]39.87[1]
SO2 (ao)-322.980[1]-300.676[1]161.9[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, (ai):Ionized aqueous solution, (l):Liquid, (g):Gas, (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)