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Na2HPO4 + NaOH → Na3PO4 + H2O

The reaction of sodium hydrogenphosphate and sodium hydroxide yields sodium phosphate and water. 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 categories

Reaction data

Chemical equation

General equation

Reaction of acid salt and base
Acid saltBrønsted acid + BaseBrønsted base
SaltConjugate base + (H2O)
Reaction of acid salt and hydroxide base
Acid saltBrønsted acid + Hydroxide baseBrønsted base
SaltConjugate base + H2OConjugate acid

Oxidation state of each atom

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
Na2HPO4Sodium hydrogenphosphate1
Brønsted acid
Acid salt
NaOHSodium hydroxide1
Brønsted base
Base
Hydroxide base

Products

Chemical formulaNameCoefficientTypeType in general
equation
Na3PO4Sodium phosphate1
Conjugate base
Salt
H2OWater1
Conjugate acid
Water

Thermodynamic changes

Changes in standard condition

Reaction of sodium hydrogenphosphate and sodium hydroxide
ΔrG−38.2 kJ/mol
K4.92 × 106
pK−6.69
Na2HPO4Crystalline solid + NaOHCrystalline solid
Na3PO4Crystalline solid + 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
−29.5−38.228.7633.91
−29.5−38.228.7633.91
per 1 mol of
−29.5−38.228.7633.91
per 1 mol of
−29.5−38.228.7633.91
per 1 mol of
−29.5−38.228.7633.91

Changes in aqueous solution

Reaction of sodium hydrogenphosphate and sodium hydroxide
ΔrG−9.5 kJ/mol
K4.62 × 101
pK−1.66
Na2HPO4Ionized aqueous solution + NaOHIonized aqueous solution
Na3PO4Ionized 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
−41.2−9.5−106.0
−41.2−9.5−106.0
per 1 mol of
−41.2−9.5−106.0
per 1 mol of
−41.2−9.5−106.0
per 1 mol of
−41.2−9.5−106.0

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
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]
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]
* (cr):Crystalline solid, (ai):Ionized aqueous solution, (g):Gas, (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
Na3PO4 (cr)-1917.40[1]-1788.80[1]173.80[1]153.47[1]
Na3PO4 (ai)-1997.9[1]-1804.5[1]-43.3[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

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)