The chemical formula of borax is Na2B4O7·10H2O.
Physical Properties of Borax:
| Properties | Details |
| Appearance | White crystalline solid |
| Boiling Point | Decomposes at high temperatures |
| Crystal Structure | Monoclinic |
| Density | 1.73 g/cm³ |
| Electrical Conductivity | Poor conductor of electricity |
| Hardness | 2 – 2.5 (Mohs scale) |
| Melting Point | 741 °C (1,366 °F) |
| Odor | Odorless |
| Solubility | Soluble in water |
| Thermal Conductivity | Low thermal conductivity |
| Transparency | Transparent to translucent |
Chemical Properties of Borax:
| Properties | Details |
| Chemical Formula | Na2B4O7·10H2O (Sodium borate decahydrate) |
| pH | Alkaline (pH ~9) |
| Hygroscopicity | It readily absorbs moisture from the air. |
| Decomposition | Decomposes when heated, releasing water and forming sodium metaborate, anhydrous borax, and boric acid. |
| Reactivity with Acids | Reacts with acids to form boric acid and a corresponding salt. |
| Reaction with Metals | Can form complexes with certain metals, such as borax bead test for identification of metal ions. |
| Flame Color Test | Gives a green flame color when heated in a flame due to the presence of boron. |
| Reducing Agent | It acts as a reducing agent in certain chemical reactions. |
| Complex Formation | Can form complexes with various compounds and ions. |
| Glass Formation | Borax is used in glass production as a flux to lower the melting point and improve the glass quality. |
Reaction of borax with Alkali Metal
| Alkali Metal | Reaction with Borax |
| Lithium (Li) | 2 Li + Na2B4O7·10H2O → 2 NaLiB4O7 + H2 ↑ |
| Sodium (Na) | 2 Na + Na2B4O7·10H2O → 4 Na2B4O7 + H2↑ |
| Potassium (K) | 2 K + Na2B4O7·10H2O → 2 KNaB4O7 + H2 ↑ |
| Rubidium (Rb) | 2 Rb + Na2B4O7·10H2O → 2 RbNaB4O7 + H2↑ |
| Cesium (Cs) | 2 Cs + Na2B4O7·10H2O → 2 CsNaB4O7 + H2↑ |
| Francium (Fr) | 2 Fr + Na2B4O7·10H2O → 2 FrNaB4O7 + H2↑ |
Reaction of borax with Alkaline Earth Metal
| Alkaline Earth Metal | Reaction with Borax |
| Beryllium (Be) | 2 Be + Na2B4O7·10H2O → 2 NaBeB4O7 + H2↑ |
| Magnesium (Mg) | 2 Mg + Na2B4O7·10H2O → 2 NaMgB4O7 + H2↑ |
| Calcium (Ca) | 2 Ca + Na2B4O7·10H2O → 2 NaCaB4O7 + H2↑ |
| Strontium (Sr) | 2 Sr + Na2B4O7·10H2O → 2 NaSrB4O7 + H2 ↑ |
| Barium (Ba) | 2 Ba + Na2B4O7·10H2O → 2 NaBaB4O7 + H2↑ |
| Radium (Ra) | 2 Ra + Na2B4O7·10H2O → 2 NaRaB4O7 + H2↑ |
Reaction of borax with Transition Metal
| Transition Metal | Reaction with Borax |
| Iron (Fe) | Fe + Na2B4O7·10H2O → NaFeB4O7 + H2↑ |
| Copper (Cu) | 2 Cu + Na2B4O7.10H2O → 2 NaCuB4O7 + H2↑ |
| Zinc (Zn) | Zn + Na2B4O7·10H2O → NaZnB4O7 + H2↑ |
| Nickel (Ni) | 2 Ni + Na2B4O7·10H2O → 2 NaNiB4O7 + H2↑ |
| Cobalt (Co) | Co + Na2B4O7·10H2O → NaCoB4O7 + H2↑ |
| Chromium (Cr) | Cr + Na2B4O7·10H2O → NaCrB4O7 + H2↑ |
| Manganese (Mn) | 3 Mn + 2 Na2B4O7·10H2O → 3 Na2MnB4O7 + 2 H2↑ |
| Titanium (Ti) | 2 Ti + 3 Na2B4O7.10H2O → 2 Na2TiB4O7 + 3 H2↑ |
| Vanadium (V) | 2 V + 3 Na2B4O7·10H2O → 2 Na2VB4O7 + 3 H2↑ |
| Molybdenum (Mo) | 3 Mo + 4 Na2B4O7·10H2O → 2 Na6Mo2B8O27 + 4 H2↑ |
| Tungsten (W) | W + 4 Na2B4O7·10H2O → Na4W2B12O31 + 4 H2↑ |
| Silver (Ag) | Ag + Na2B4O7·10H2O → NaAgB4O7 + H2↑ |
| Gold (Au) | 2 Au + 3 Na2B4O7·10H2O → 2 Na3AuB4O7 + 3 H2↑ |
Reaction of borax with Non-Transition Metal
| Non-Transition Metal | Reaction with Borax |
| Aluminum (Al) | 2 Al + 3 Na2B4O7·10H2O → 3 NaAlB4O7 + 3 H2↑ |
| Magnesium (Mg) | Mg + Na2B4O7·10H2O → NaMgB4O7 + H2↑ |
| Calcium (Ca) | Ca + Na2B4O7·10H2O → NaCaB4O7 + H2↑ |
| Sodium (Na) | 2 Na + Na2B4O7·10H2O → 4 Na2B4O7 + H2↑ |
| Potassium (K) | 2 K + Na2B4O7·10H2O → 2 KNaB4O7 + H2↑ |
| Lithium (Li) | 2 Li + Na2B4O7·10H2O → 2 NaLiB4O7 + H2↑ |
| Beryllium (Be) | 2 Be + Na2B4O7·10H2O → 2 NaBeB4O7 + H2↑ |
| Barium (Ba) | 2 Ba + Na2B4O7·10H2O → 2 NaBaB4O7 + H2↑ |
| Strontium (Sr) | 2 Sr + Na2B4O7·10H2O → 2 NaSrB4O7 + H2↑ |
| Radium (Ra) | 2 Ra + Na2B4O7·10H2O → 2 NaRaB4O7 + H2↑ |
| Aluminum (Al) | 2 Al + 3 Na2B4O7·10H2O → 3 NaAlB4O7 + 3 H2↑ |
| Gallium (Ga) | 2 Ga + 3 Na2B4O7·10H2O → 2 NaGaB4O7 + 3 H2↑ |
| Indium (In) | 2 In + 3 Na2B4O7·10H2O → 2 NaInB4O7 + 3 H2↑ |
| Thallium (Tl) | 2 Tl + 3 Na2B4O7·10H2O → 2 NaTlB4O7 + 3 H2↑ |
Reaction of borax with Non-Metal
| Non-Metal | Reaction with Borax |
| Hydrogen (H) | 2 H2 + Na2B4O7·10H2O → 4 NaBO2 + 9 H2O |
| Carbon (C) | C + 2 Na2B4O7·10H2O → Na2B4O7+ Na2CO3 + CO2 ↑ + 10 H2O |
| Nitrogen (N) | 4 NH4 + Na2B4O7·10H2O → Na2B4O7 + 4 NaOH + 8 H2O + N2 ↑ |
| Oxygen (O) | 4 Na2B4O7·10H2O → 2 Na2B8O13 + 13 H2O + 3 O2 ↑ |
| Phosphorus (P) | 2 P4 + 15 Na2B4O7·10H2O → 14 NaBO2+ Na3PO4 + 30 H2O |
| Sulfur (S) | 8 S + 15 Na2B4O7·10H2O → 15 NaBO2+ Na2S2O3 + 30 H2O |
| Fluorine (F) | 2 F2 + 4 Na2B4O7·10H2O → 8 NaBO2+ 2 NaBF4 + 20 H2O + O2 ↑ |
| Chlorine (Cl) | 4 Cl2 + 8 Na2B4O7·10H2O → 16 NaBO2+ 2 Na2B6O10Cl2 + 40 H2O + O2 ↑ |
| Bromine (Br) | 4 Br2 + 8 Na2B4O7·10H2O → 16 NaBO2+ 2 Na2B6O10Br2 + 40 H2O + O2 ↑ |
| Iodine (I) | 4 I2 + 8 Na2B4O7·10H2O → 16 NaBO2+ 2 Na2B6O10I2 + 40 H2O + O2 ↑ |
Reaction of borax with Metalloid
| Metalloid | Reaction with Borax |
| Boron (B) | 2 B + 3 Na2B4O7·10H2O → Na2B4O7 + 6 NaBO2+ 6 H2 ↑ |
| Silicon (Si) | 2 Si + Na2B4O7·10H2O → Na4SiO4 + 5 NaBO2+ 10 H2↑ |
| Germanium (Ge) | 2 Ge + Na2B4O7·10H2O → Na4GeO4 + 5 NaBO2+ 10 H2↑ |
| Arsenic (As) | 2 As + 5 Na2B4O7·10H2O → Na4AsO4 + 5 NaBO2+ 10 H2↑ |
| Antimony (Sb) | 2 Sb + 5 Na2B4O7·10H2O → Na4SbO4 + 5 NaBO2+ 10 H2↑ |
| Tellurium (Te) | 2 Te + 5 Na2B4O7·10H2O → Na4TeO4 + 5 NaBO2+ 10 H2↑ |
| Polonium (Po) | 2 Po + 5 Na2B4O7·10H2O → Na4PoO4 + 5 NaBO2 + 10 H2↑ |