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2Na + H3PO4 → Na2HPO4 + H2↑

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Reaction of sodium and phosphoric acid
2NaSodium + H3PO4Phosphoric acid
⟶
Na2HPO4Sodium hydrogenphosphate + H2↑Hydrogen

The reaction of sodium and phosphoric acid yields sodium hydrogenphosphate 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

Reaction of sodium and phosphoric acid
2NaSodium + H3PO4Phosphoric acid
⟶
Na2HPO4Sodium hydrogenphosphate + H2↑Hydrogen

General equation

Reaction of reducing species and reducible species
Reducing speciesReducing agent + Reducible speciesOxidizing agent
⟶
ProductOxidation product + ProductReduction product
Reaction of active metal and acid
Active metalReducing agent + AcidOxidizing agent
⟶
SaltOxidation product + H2Reduction product

Oxidation state of each atom

Reaction of sodium and phosphoric acid

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
NaSodium2
Reducing
Reducing
Active metal
H3PO4Phosphoric acid1
Oxidizing
Reducible
Acid

Products

Chemical formulaNameCoefficientTypeType in general
equation
Na2HPO4Sodium hydrogenphosphate1
Oxidized
–
Salt
H2Hydrogen1
Reduced
–
Hydrogen

Thermodynamic changes

Changes in standard condition

Reaction of sodium and phosphoric acid
◆
ΔrG−489.1 kJ/mol
K4.86 × 1085
pK−85.69
2NaCrystalline solid + H3PO4Crystalline solid
⟶
Na2HPO4Crystalline solid + H2↑Gas
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
−469.1−489.168.261.59
per 1 mol of
−234.6−244.634.130.795
per 1 mol of
−469.1−489.168.261.59
−469.1−489.168.261.59
per 1 mol of
−469.1−489.168.261.59

Changes in aqueous solution (1)

Reaction of sodium and phosphoric acid
◆
ΔrG−470.44 kJ/mol
K2.62 × 1082
pK−82.42
2NaCrystalline solid + H3PO4Un-ionized aqueous solution
⟶
Na2HPO4Ionized aqueous solution + H2↑Gas
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
−484.04−470.44−45.4–
per 1 mol of
−242.02−235.22−22.7–
per 1 mol of
−484.04−470.44−45.4–
−484.04−470.44−45.4–
per 1 mol of
−484.04−470.44−45.4–

Changes in aqueous solution (2)

Reaction of sodium and phosphoric acid
◆
ΔrG−452.8 kJ/mol
K2.12 × 1079
pK−79.33
2NaCrystalline solid + H3PO4Un-ionized aqueous solution
⟶
Na2HPO4Ionized aqueous solution + H2↑Un-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
−488.2−452.8401–
per 1 mol of
−244.1−226.4201–
per 1 mol of
−488.2−452.8401–
−488.2−452.8401–
per 1 mol of
−488.2−452.8401–

Changes in aqueous solution (3)

Reaction of sodium and phosphoric acid
◆
ΔrG−594.3 kJ/mol
K1.31 × 10104
pK−104.12
2NaCrystalline solid + H3PO4Ionized aqueous solution
⟶
Na2HPO4Ionized aqueous solution + H2↑Gas
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
−495.0−594.3333.1–
per 1 mol of
−247.5−297.1166.6–
per 1 mol of
−495.0−594.3333.1–
−495.0−594.3333.1–
per 1 mol of
−495.0−594.3333.1–

Changes in aqueous solution (4)

Reaction of sodium and phosphoric acid
◆
ΔrG−576.7 kJ/mol
K1.08 × 10101
pK−101.03
2NaCrystalline solid + H3PO4Ionized aqueous solution
⟶
Na2HPO4Ionized aqueous solution + H2↑Un-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
−499.2−576.7779–
per 1 mol of
−249.6−288.4390–
per 1 mol of
−499.2−576.7779–
−499.2−576.7779–
per 1 mol of
−499.2−576.7779–

Changes in aqueous solution (5)

Reaction of sodium and phosphoric acid
◆
ΔrG−470.44 kJ/mol
K2.62 × 1082
pK−82.42
2NaCrystalline solid + H3PO4Un-ionized aqueous solution
⟶
Na2HPO4Ionized aqueous solution + H2↑Gas
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
−484.04−470.44−45.4–
per 1 mol of
−242.02−235.22−22.7–
per 1 mol of
−484.04−470.44−45.4–
−484.04−470.44−45.4–
per 1 mol of
−484.04−470.44−45.4–

Changes in aqueous solution (6)

Reaction of sodium and phosphoric acid
◆
ΔrG−452.8 kJ/mol
K2.12 × 1079
pK−79.33
2NaCrystalline solid + H3PO4Un-ionized aqueous solution
⟶
Na2HPO4Ionized aqueous solution + H2↑Un-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
−488.2−452.8401–
per 1 mol of
−244.1−226.4201–
per 1 mol of
−488.2−452.8401–
−488.2−452.8401–
per 1 mol of
−488.2−452.8401–

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
Na (cr)0[1]0[1]51.21[1]28.24[1]
Na (g)107.32[1]76.761[1]153.712[1]20.786[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, (g):Gas, (l):Liquid, (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
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]–
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, (ai):Ionized aqueous solution, (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)