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Chemical reactions
4B + 8NaOH → Na2B4O7 + 6NaH + H2O

4B + 8NaOH → Na₂B₄O₇ + 6NaH + H₂O

Last updated: June 13, 2022

Reaction of boron and sodium hydroxide: 4BBoron + 8NaOHSodium hydroxide
⟶
Na₂B₄O₇Sodium tetraborate + 6NaHSodium hydride + H₂OWater

The reaction of boron and sodium hydroxide yields sodium tetraborate, sodium hydride, and water (Other reactions are here). This reaction is an oxidation-reduction reaction and is classified as follows:

Reaction of nonmetal and hydroxide base

Table of contents

Reaction data

Reactants

Chemical formula	Name	Coefficient	Type	Type in general equation
B	Boron	4	Reducing	Nonmetal
NaOH	Sodium hydroxide	8	–	Hydroxide base

Products

Chemical formula	Name	Coefficient	Type	Type in general equation
Na₂B₄O₇	Sodium tetraborate	1	Oxidized	Oxoacid salt
NaH	Sodium hydride	6	–	Hydride
H₂O	Water	1	–	Hydride

Thermodynamic changes

Changes in standard condition (1)

Reaction of boron and sodium hydroxide ◆ Δ_rG −497.9 kJ/mol K 1.69 × 10⁸⁷ pK −87.23: 4BCrystalline solid + 8NaOHCrystalline solid
⟶
Na₂B₄O₇Crystalline solid + 6NaHCrystalline solid + H₂OLiquid

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	−509.7	−497.9	−39.53	−40.21
per 1 mol of Boron	−127.4	−124.5	−9.883	−10.05
per 1 mol of Sodium hydroxide	−63.71	−62.24	−4.941	−5.026
per 1 mol of Sodium tetraborate	−509.7	−497.9	−39.53	−40.21
per 1 mol of Sodium hydride	−84.95	−82.98	−6.588	−6.702
per 1 mol of Water	−509.7	−497.9	−39.53	−40.21

Changes in standard condition (2)

Reaction of boron and sodium hydroxide ◆ Δ_rG −478.7 kJ/mol K 7.32 × 10⁸³ pK −83.86: 4BCrystalline solid + 8NaOHCrystalline solid
⟶
Na₂B₄O₇Amorphous solid + 6NaHCrystalline solid + H₂OLiquid

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	−489.7	−478.7	−36.2	–
per 1 mol of Boron	−122.4	−119.7	−9.05	–
per 1 mol of Sodium hydroxide	−61.21	−59.84	−4.53	–
per 1 mol of Sodium tetraborate	−489.7	−478.7	−36.2	–
per 1 mol of Sodium hydride	−81.62	−79.78	−6.03	–
per 1 mol of Water	−489.7	−478.7	−36.2	–

Changes in standard condition (3)

Reaction of boron and sodium hydroxide: 4BAmorphous solidx denotes undetermined zero point entropy + 8NaOHCrystalline solid
⟶
Na₂B₄O₇Crystalline solid + 6NaHCrystalline solid + H₂OLiquid

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	−524.9	–	−9.56	−43.73
per 1 mol of Boron	−131.2	–	−2.39	−10.93
per 1 mol of Sodium hydroxide	−65.61	–	−1.20	−5.466
per 1 mol of Sodium tetraborate	−524.9	–	−9.56	−43.73
per 1 mol of Sodium hydride	−87.48	–	−1.59	−7.288
per 1 mol of Water	−524.9	–	−9.56	−43.73

Changes in standard condition (4)

Reaction of boron and sodium hydroxide: 4BAmorphous solidx denotes undetermined zero point entropy + 8NaOHCrystalline solid
⟶
Na₂B₄O₇Amorphous solid + 6NaHCrystalline solid + H₂OLiquid

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	−504.9	–	−6.2	–
per 1 mol of Boron	−126.2	–	−1.6	–
per 1 mol of Sodium hydroxide	−63.11	–	−0.78	–
per 1 mol of Sodium tetraborate	−504.9	–	−6.2	–
per 1 mol of Sodium hydride	−84.15	–	−1.0	–
per 1 mol of Water	−504.9	–	−6.2	–

Changes in aqueous solution

Reaction of boron and sodium hydroxide ◆ Δ_rG −213.4 kJ/mol K 2.43 × 10³⁷ pK −37.39: 4BCrystalline solid + 8NaOHIonized aqueous solution
⟶
Na₂B₄O₇Ionized aqueous solution + 6NaHCrystalline solid + H₂OLiquid

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	–	−213.4	–	–
per 1 mol of Boron	–	−53.35	–	–
per 1 mol of Sodium hydroxide	–	−26.68	–	–
per 1 mol of Sodium tetraborate	–	−213.4	–	–
per 1 mol of Sodium hydride	–	−35.57	–	–
per 1 mol of Water	–	−213.4	–	–

Thermodynamic data of reactants

Chemical formula	Standard enthalpy of formation Δ_fH° kJ · mol⁻¹	Standard Gibbs energy of formation Δ_fG° kJ · mol⁻¹	Standard molar entropy S° J · K⁻¹ · mol⁻¹	Standard molar heat capacity at constant pressure C_p° J · K⁻¹ · mol⁻¹
B (cr)	0^[1]	0^[1]	5.86^[1]	11.09^[1]
B (am) x denotes undetermined zero point entropy	3.8^[1]	–	6.53+x^[1]	11.97^[1]
B (g)	562.7^[1]	518.8^[1]	153.45^[1]	20.799^[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, (am):Amorphous solid, (g):Gas, (ai):Ionized aqueous solution, (l):Liquid

Thermodynamic data of products

Chemical formula	Standard enthalpy of formation Δ_fH° kJ · mol⁻¹	Standard Gibbs energy of formation Δ_fG° kJ · mol⁻¹	Standard molar entropy S° J · K⁻¹ · mol⁻¹	Standard molar heat capacity at constant pressure C_p° J · K⁻¹ · mol⁻¹
Na₂B₄O₇ (cr)	-3291.1^[1]	-3096.0^[1]	189.54^[1]	186.77^[1]
Na₂B₄O₇ (am)	-3271.1^[1]	-3076.8^[1]	192.9^[1]	–
Na₂B₄O₇ (ai)	–	-3128.7^[1]	–	–
Na₂B₄O₇ (cr) 4 hydrate	-4507.4^[1]	–	–	–
Na₂B₄O₇ (cr) 5 hydrate	-4802.4^[1]	–	–	–
Na₂B₄O₇ (cr) 10 hydrate	-6288.6^[1]	-5516.0^[1]	586^[1]	615^[1]
NaH (cr)	-56.275^[1]	-33.46^[1]	40.016^[1]	36.401^[1]
NaH (g)	130.25^[1]	108.85^[1]	188.377^[1]	30.29^[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, (am):Amorphous solid, (ai):Ionized aqueous solution, (g):Gas, (l):Liquid

References

List of references

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
https://doi.org/10.18434/M32124
National Institute of Standards and Technology (NIST)
Citation list

Δ_rG	−497.9 kJ/mol
K	1.69 × 10⁸⁷
pK	−87.23

Δ_rG	−478.7 kJ/mol
K	7.32 × 10⁸³
pK	−83.86

Δ_rG	−213.4 kJ/mol
K	2.43 × 10³⁷
pK	−37.39

4B + 8NaOH → Na2B4O7 + 6NaH + H2O

Reaction data

Chemical equation

General equation

Oxidation state of each atom