H3PO4 + 2NaOH → Na2HPO4 + 2H2O
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The reaction of phosphoric acid and sodium hydroxide yields sodium hydrogenphosphate and water (Other reactions are here). This reaction is an acid-base reaction and is classified as follows:
Table of contents
Reaction data
Chemical equation
- Reaction of phosphoric acid and sodium hydroxide
General equation
- Reaction of acid and base
- AcidBrønsted acid + BaseBrønsted base ⟶ SaltConjugate base + (H2O)(Conjugate acid)
- Reaction of acid and hydroxide base
- AcidBrønsted acid + Hydroxide baseBrønsted base ⟶ SaltConjugate base + H2OConjugate acid
- Reaction of weak acid and strong base
- Weak acidBrønsted acid + Strong baseBrønsted base ⟶ Salt of weak acid and strong baseConjugate base + (H2O)(Conjugate acid)
Oxidation state of each atom
- Reaction of phosphoric acid and sodium hydroxide
Reactants
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| H3PO4 | Phosphoric acid | 1 | Brønsted acid | Acid Weak acid |
| NaOH | Sodium hydroxide | 2 | Brønsted base | Base Hydroxide base Strong base |
Products
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| Na2HPO4 | Sodium hydrogenphosphate | 1 | Conjugate base | Salt Salt of weak acid and strong base |
| H2O | Water | 2 | Conjugate acid | Water |
Thermodynamic changes
Changes in standard condition
- Reaction of phosphoric acid and sodium hydroxide◆
ΔrG −204.4 kJ/mol K 6.45 × 1035 pK −35.81
| 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 | −189.5 | −204.4 | 50.91 | 60.75 |
per 1 mol of | −189.5 | −204.4 | 50.91 | 60.75 |
per 1 mol of | −94.75 | −102.2 | 25.45 | 30.38 |
per 1 mol of | −189.5 | −204.4 | 50.91 | 60.75 |
per 1 mol of | −94.75 | −102.2 | 25.45 | 30.38 |
Changes in aqueous solution (1)
- Reaction of phosphoric acid and sodium hydroxide◆
ΔrG −106.40 kJ/mol K 4.37 × 1018 pK −18.64
| 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 | −115.47 | −106.40 | −30.1 | – |
per 1 mol of | −115.47 | −106.40 | −30.1 | – |
per 1 mol of | −57.735 | −53.200 | −15.1 | – |
per 1 mol of | −115.47 | −106.40 | −30.1 | – |
per 1 mol of | −57.735 | −53.200 | −15.1 | – |
Changes in aqueous solution (2)
- Reaction of phosphoric acid and sodium hydroxide◆
ΔrG −230.2 kJ/mol K 2.13 × 1040 pK −40.33
| 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 | −126.4 | −230.2 | 348.4 | – |
per 1 mol of | −126.4 | −230.2 | 348.4 | – |
per 1 mol of | −63.20 | −115.1 | 174.2 | – |
per 1 mol of | −126.4 | −230.2 | 348.4 | – |
per 1 mol of | −63.20 | −115.1 | 174.2 | – |
Changes in aqueous solution (3)
- Reaction of phosphoric acid and sodium hydroxide◆
ΔrG −106.40 kJ/mol K 4.37 × 1018 pK −18.64
| 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 | −115.47 | −106.40 | −30.1 | – |
per 1 mol of | −115.47 | −106.40 | −30.1 | – |
per 1 mol of | −57.735 | −53.200 | −15.1 | – |
per 1 mol of | −115.47 | −106.40 | −30.1 | – |
per 1 mol of | −57.735 | −53.200 | −15.1 | – |
Thermodynamic data of reactants
| Chemical formula | Standard 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 |
|---|---|---|---|---|
| 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] | – | – | – |
| 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, (l):Liquid, (ai):Ionized aqueous solution, (ao):Un-ionized aqueous solution, (g):Gas
Thermodynamic data of products
| Chemical formula | Standard 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] | – |
| 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
- 1Janiel J. Reed (1989)The NBS Tables of Chemical Thermodynamic Properties: Selected Values for Inorganic and C1 and C2 Organic Substances in SI UnitsNational Institute of Standards and Technology (NIST)
- ^ ΔfH°, -1279.0 kJ · mol−1
- ^ ΔfG°, -1119.1 kJ · mol−1
- ^ S°, 110.50 J · K−1 · mol−1
- ^ Cp°, 106.06 J · K−1 · mol−1
- ^ ΔfH°, -1266.9 kJ · mol−1
- ^ ΔfH°, -1277.4 kJ · mol−1
- ^ ΔfG°, -1018.7 kJ · mol−1
- ^ S°, -220.3 J · K−1 · mol−1
- ^ ΔfH°, -1288.34 kJ · mol−1
- ^ ΔfG°, -1142.54 kJ · mol−1
- ^ S°, 158.2 J · K−1 · mol−1
- ^ ΔfH°, -1431.3 kJ · mol−1
- ^ ΔfG°, -1242.1 kJ · mol−1
- ^ S°, 129.16 J · K−1 · mol−1
- ^ Cp°, 126.02 J · K−1 · mol−1
- ^ ΔfH°, -1568.83 kJ · mol−1
- ^ ΔfH°, -425.609 kJ · mol−1
- ^ ΔfG°, -379.494 kJ · mol−1
- ^ S°, 64.455 J · K−1 · mol−1
- ^ Cp°, 59.54 J · K−1 · mol−1
- ^ ΔfH°, -207.1 kJ · mol−1
- ^ ΔfG°, -210.0 kJ · mol−1
- ^ S°, 228.43 J · K−1 · mol−1
- ^ Cp°, 48.37 J · K−1 · mol−1
- ^ ΔfH°, -470.114 kJ · mol−1
- ^ ΔfG°, -419.150 kJ · mol−1
- ^ S°, 48.1 J · K−1 · mol−1
- ^ Cp°, -102.1 J · K−1 · mol−1
- ^ ΔfH°, -734.543 kJ · mol−1
- ^ ΔfG°, -629.338 kJ · mol−1
- ^ S°, 99.50 J · K−1 · mol−1
- ^ Cp°, 90.17 J · K−1 · mol−1
- ^ ΔfH°, -1019.076 kJ · mol−1
- ^ ΔfG°, -873.091 kJ · mol−1
- ^ S°, 195.979 J · K−1 · mol−1
- ^ Cp°, 239.41 J · K−1 · mol−1
- ^ ΔfH°, -1459.798 kJ · mol−1
- ^ ΔfG°, -1236.356 kJ · mol−1
- ^ S°, 286.089 J · K−1 · mol−1
- ^ Cp°, 354.43 J · K−1 · mol−1
- ^ ΔfH°, -1605.15 kJ · mol−1
- ^ ΔfG°, -1356.64 kJ · mol−1
- ^ S°, 318.70 J · K−1 · mol−1
- ^ ΔfH°, -1894.31 kJ · mol−1
- ^ ΔfG°, -1596.34 kJ · mol−1
- ^ S°, 386.06 J · K−1 · mol−1
- ^ ΔfH°, -2469.02 kJ · mol−1
- ^ ΔfG°, -2073.80 kJ · mol−1
- ^ S°, 526.31 J · K−1 · mol−1
- ^ ΔfH°, -1748.1 kJ · mol−1
- ^ ΔfG°, -1608.2 kJ · mol−1
- ^ S°, 150.50 J · K−1 · mol−1
- ^ Cp°, 135.31 J · K−1 · mol−1
- ^ ΔfH°, -1772.38 kJ · mol−1
- ^ ΔfG°, -1612.98 kJ · mol−1
- ^ S°, 84.5 J · K−1 · mol−1
- ^ ΔfH°, -2346.0 kJ · mol−1
- ^ ΔfG°, -2088.5 kJ · mol−1
- ^ S°, 221.3 J · K−1 · mol−1
- ^ ΔfH°, -3821.7 kJ · mol−1
- ^ ΔfG°, -3279.8 kJ · mol−1
- ^ S°, 434.59 J · K−1 · mol−1
- ^ ΔfH°, -5297.8 kJ · mol−1
- ^ ΔfG°, -4467.8 kJ · mol−1
- ^ S°, 633.83 J · K−1 · mol−1
- ^ ΔfH°, -285.830 kJ · mol−1
- ^ ΔfG°, -237.129 kJ · mol−1
- ^ S°, 69.91 J · K−1 · mol−1
- ^ Cp°, 75.291 J · K−1 · mol−1
- ^ ΔfH°, -241.818 kJ · mol−1
- ^ ΔfG°, -228.572 kJ · mol−1
- ^ S°, 188.825 J · K−1 · mol−1
- ^ Cp°, 33.577 J · K−1 · mol−1