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Borax is a natural mineral and a salt of Boric acid. It is a colorless, soft compound. It is a chemical element that exists in both crystalline and amorphous forms. Borax can also be known as Sodium tetraborate, Sodium Borate, or Disodium Tetraborate. It is widely known for its fungus or anti-fungal prevention.
NCERT Solutions For: Class 12 Chemistry Chapter 7 The p-Block Elements
Key Terms: Tetraborate, Borax, Chemical, Compounds, Tincal, Sodium, Sodium Borate, Sodium Tetraborate, Disodium Tetraborate
What is Borax?
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Borax is a salt, a hydrated borate of sodium, and is also known as sodium borate, sodium tetraborate, or disodium tetraborate. It is used as a complexing agent, water softening agent & fungicide. The main forms of borax are anhydrous and decahydrate salt and at times pentahydrate salt. The term Borax is used for several chemical compounds or close related minerals. Different borax found is anhydrous sodium tetraborate (Na2B4O7), & sodium tetraborate pentahydrate (Na2B4O7·5H2O). Equivalently the octahydrate, (Na2B4O5(OH)4·8H2O) is the same.
Also Read:
| Boric Acid | Diborane | Group 14 Elements |
| Group 15 Elements | Dinitrogen | Ammonia |
| Oxides of Nitrogen | Nitric Acid | Phosphine |
Structure of Borax
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The molecules of Borax consist of [B4O5 (OH)4]2- ions, and 8 water molecules are connected to it. It is made up of triangular and two tetrahedral units. With this structural form of Borax, the updated chemical formula of Borax is Na2[B4O5(OH)4].8H2ONa2[B4O5(OH)4].8H2O. The structural form of Borax is given below:
Structure of Borax
Occurrence of Borax
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Borax was first discovered in the dry lake beds of Tibet and was imported to Arabian Estates. It is found in the name of Tincal. It is the crude form of Borax and it contains several impurities. The repeated Evaporation in the seasonal lakes leads to the formation of Borax. It is used as a cleaning product by the native tribes. Borax in the form of Tincal is also found in Ceylon, Kashmir, and California.
Read More: Oxoacids of Phosphorus
Preparation Method of Borax
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From Boric Acid: With the reaction of Boric Acid with Sodium Carbonate, Borax in small quantities can be prepared. It is a neutralization reaction. The chemical reaction for the same will be as:
4H3BO3 + Na2CO3 → Na2B4O7 + 6H2O + CO2
From Tincal: Borax can be prepared fromTincal by dissolving it in the Water that is boiled. The solution obtained can be used to remove insoluble impurities by filtering such as clay, sand, etc. The solution further can be concentrated to obtain a pure form of crystals of Borax. The chemical formula for the same would be (Na2B4O7).
From Colemanite: The Colemanite mineral in this method is brought into powdered form & then boiled with sodium carbonate solution. Sodium Metaborates & Borax as a result are formed.
Further, the white precipitate of Calcium Carbonate is removed from the obtained reaction by the process of filtration. The solution after the concentration and cooling solution gives the pure form of the Borax. The chemical equation for the same is as:
4NaBO2 + CO2→ Na2B4O7 + Na2CO3
Properties of Borax
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The physical and chemical properties of Borax are as follows:
Physical Properties:
- Borax is the white crystalline solid compound
- The molar mass of Borax is 381.38g/mol (decahydrate) & 202.2g/mol (anhydrous form)
- The density of Borax is 1.7g/cm3 (decahydrate)
- The boiling point of Borax is 1,575oC (anhydrous)
- The melting point of Borax is 743oC (anhydrous)
- The refractive index of Borax is 1.472 (decahydrate)
Chemical Properties:
- Borax is flammable or ignitable. It gives a yellowish-green flame.
- Borax is a soluble compound with solubility in the water at 31.7g/L
- Borax has a high solubility in ethylene glycol & low solubility in Acetone.
- Borax can react with hydrochloric acid to form Boric Acid. The reaction is as follows: Na2[B4O5(OH)4].8H2O→Na2B4O7+10H2O
Uses of Borax
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- Borax is used as an alkalizer for pharmaceutical purposes.
- Borax is used as a food preservative.
- Borax can be used for welding of Iron & Steel mixture of Ammonium Chloride & Borax is used as a flux.
- Borax is used in the test of diabetes of Mellitus.
- Borax is used as a water softening agent.
- Borax is used for stiffening candle wicks.
- Borax is used to make buffer solutions.
- Borax is used as a mild antiseptic.
Read more:
| Ozone | Sulphur Dioxide | Oxoacids of Sulphur |
| Sulphuric Acid | Interhalogen Compounds | Aqua regia |
| Brown Ring Test | Organometallic compounds | Noble gases |
Things to Remember
- Borax (Na2B4O7) is one of the most essential compounds of Boron.
- Borax on hydrolysis, gives an alkaline solution to the Borax. It is because it gives a weak acid (H3BO3) on Hydrolysis & a strong Base.
- Borax is the source of Borate Ions that are good at forming complex Ions in water. Borate with a suitable polymer bed helps to Chromatograph the non-glycated hemoglobin distinctively from glycated hemoglobin.
Previous Years’ Questions
- Which structure for XeO3 and XeF4 are consistent with the VSEPR model?
- The noble gas used in atomic reactors is…?
- Number of lone pair (s) in XeOF4 is/are…?
- Xenon hexaflouride reacts with silica to form a xenon compound X…?
- The noble gas that does NOT occur in the atmosphere is… [JEE Main 2019]
- The last element of the p-block in 6th period is represented by the outer most electronic configuration…? [KCET 2020]
- Noble gases are group of elements which exhibit very?
- Noble gases are sparingly soluble in water due to…?
- The ease of liquifiaction of noble gases decreases in the order…?
- Noble gases are also known as aerogens because…?
- Maximum number of compounds are formed by…?
- The noble gas forming maximum number of compounds is…? [BHU UET 1980]
- Which one of the following reactions of xenon compounds is not feasible?
Sample Questions
Ques: Is Borax same as the Baking soda? (2 marks)
Ans: Baking soda and borax are derivatives of numerous chemical compounds widely found. Borax is categorized as white solid sodium borate, whereas baking soda is categorized as white crystal sodium bicarbonate.
Ques: Explain the Borax Bread test. (3 marks)
Ans: Borax metals into a clear liquid which solidifies to a transparent glass-like bead when heated. The glass bead is commonly known as borax bead and is employed in qualitative analysis for the detection of Ni2+, Cr3+, C42+, and Mn+2.
When colored salt-containing these cations are heated with a borax bead on a platinum wire, it forms metaborates This test is called the borax bead test.
CoSO44 →CoO+SO3
CoO+B2O3→Co(BO2)2
Ques: Whether Borax is Basic or Acidic? (2 marks)
Ans: A weak base, Borax is also used in buffer solutions and photographic developers. As Boron is mandatory in the calcium cycle of plants, Borax or Boric Acid is often added to Boron’s poor soils as a fertilizer. Boric Acid is obtained by the action of strong Acids on Borax & is used as a mild disinfectant.
Ques: What is the pH level of Borax? (1 mark)
Ans: Borax is the Sodium Tetraborate Decahydrate (Na2B4O7. 10H2O). When dissolved in water, is hydrolyzed to Boric Acid OH- anions, yielding a pH is at 9.13
Ques: List the safety measure to be followed while using borax to avoid risks. (5 marks)
Ans:
- Always use Borax in a place where the circulation of air is very good with proper ventilation.
- Always use gloves while handling Borax.
- In the case where Borax comes in contact with your skin or eyes, thoroughly wash them for 10 minutes.
- Washing hands after using Borax and avoiding eating food or drinking without washing hands.
- Always contact the doctor if the situation gets out of control.
Ques: Why is Borax dangerous? (2 marks)
Ans: When penetration happens through the skin or eye touch, inhalation, or swallowing, Borax can be irritating. Studies in Poison indicate that misuse of borax-based pesticides with symptoms such as nausea, skin rash, vomiting, eye irritation, oral irritation, and respiratory effects can result in acute toxicity.
Ques: Differentiate between Borax & Boric Acid. (2 marks)
Ans:
| Borax | Boric Acid |
| Borax is hydrated salt of boric acid. | Boric acid is a weak, monobasic Lewis acid of Boron. |
| It is also known as Sodium borate decahydrate or Sodium tetraborate decahydrate. | It is also known as acid, hydrogen borate, or orthoboric acid. |
Ques: Is borax and boric powder the same? (2 marks)
Ans: Borax and Boric Acid are two different formulations of the same compound. Borax is a mineral used in cleaning materials extracted straight from the earth (a type of the element Boron). The extracted, distilled and refined type of boric acid is used in a number of chemical products.
Ques: Is Borax safe for humans? (2 marks)
Ans: Borax can not be swallowed or inhaled safely as it is quick for the body to break down when it is either inhaled or swallowed, according to the Toxicology Data Network of the NLM. However, both severe poisoning and organ injury will result if inhalation or absorption occurs.
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