Caustic soda, also known as sodium hydroxide, is a highly alkaline inorganic compound widely used in industrial and laboratory settings. It is a white, crystalline solid at room temperature and is highly soluble in water, releasing significant heat upon dissolution.
| Parameter | Details | Explanation |
|---|---|---|
| Chemical Formula | NaOH | Represents one sodium atom (Na), one oxygen atom (O), and one hydrogen atom (H) |
| Chemical Name | Sodium Hydroxide | The systematic IUPAC name for caustic soda |
| Common Names | Caustic Soda, Lye, Soda Lye | Trade and common names used in industry and households |
| Molecular Formula | NaOH | Same as chemical formula; shows atomic composition |
| Structural Formula | Na⁺—O⁻—H | Shows ionic bonding between sodium and hydroxide ions |
| Empirical Formula | NaOH | Simplest whole-number ratio of atoms in the compound |
| Ionic Formula | Na⁺ + OH⁻ | Shows the ionic nature: sodium cation and hydroxide anion |
| Molecular Weight | 40 g/mol | Sum of atomic masses: Na(23) + O(16) + H(1) = 40 |
| Molecular Mass | 39.997 g/mol | Precise molecular mass using exact atomic weights |
| Molar Mass | 40 g/mol | Mass of one mole of NaOH |
| Reaction Type | Chemical Equation | Description |
|---|---|---|
| Chlor-Alkali Process | 2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂ | Industrial production via electrolysis of brine |
| Lime-Soda Process | Na₂CO₃ + Ca(OH)₂ → 2NaOH + CaCO₃ | Traditional method using sodium carbonate and slaked lime |
| Reaction with Sodium | 2Na + 2H₂O → 2NaOH + H₂ | Direct reaction of sodium metal with water |
| Acid Used | Chemical Equation | Products Formed |
|---|---|---|
| Hydrochloric Acid | NaOH + HCl → NaCl + H₂O | Sodium chloride (table salt) + water |
| Sulfuric Acid | 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O | Sodium sulfate + water |
| Nitric Acid | NaOH + HNO₃ → NaNO₃ + H₂O | Sodium nitrate + water |
| Acetic Acid | NaOH + CH₃COOH → CH₃COONa + H₂O | Sodium acetate + water |
| Phosphoric Acid | 3NaOH + H₃PO₄ → Na₃PO₄ + 3H₂O | Sodium phosphate + water |
| Reactant | Chemical Equation | Products |
|---|---|---|
| Chlorine Gas | 2NaOH + Cl₂ → NaCl + NaOCl + H₂O | Sodium chloride + sodium hypochlorite (bleach) |
| Carbon Dioxide | 2NaOH + CO₂ → Na₂CO₃ + H₂O | Sodium carbonate + water |
| Sulfur Dioxide | 2NaOH + SO₂ → Na₂SO₃ + H₂O | Sodium sulfite + water |
| Aluminum | 2Al + 2NaOH + 2H₂O → 2NaAlO₂ + 3H₂ | Sodium aluminate + hydrogen gas |
| Process | Equation | Explanation |
|---|---|---|
| Ionization in Water | NaOH (s) → Na⁺ (aq) + OH⁻ (aq) | Complete dissociation into ions, making it a strong base |
| Property | Value/Description |
|---|---|
| Physical State | White crystalline solid |
| Melting Point | 318°C (604°F) |
| Boiling Point | 1,388°C (2,530°F) |
| Density | 2.13 g/cm³ |
| Solubility in Water | Highly soluble (111 g/100 mL at 20°C) |
| pH Value | 13-14 (strong base) |
| Nature | Hygroscopic (absorbs moisture from air) |
| Corrosiveness | Highly corrosive to organic tissues |
| Formula Type | Equation | Variables |
|---|---|---|
| Molarity Formula | M = n/V | M = Molarity, n = moles of NaOH, V = Volume in liters |
| Mass Percentage | % = (Mass of NaOH / Total mass of solution) × 100 | Used for commercial solutions |
| Dilution Formula | M₁V₁ = M₂V₂ | M₁,V₁ = initial concentration & volume; M₂,V₂ = final values |
| Normality | N = M × n-factor | For NaOH, n-factor = 1 (one OH⁻ ion) |
The chemical formula of caustic soda is NaOH, which represents sodium hydroxide. It consists of one sodium atom (Na), one oxygen atom (O), and one hydrogen atom (H).
No, caustic soda (NaOH) and baking soda (NaHCO₃) are different compounds. Caustic soda is sodium hydroxide, a strong base, while baking soda is sodium bicarbonate, a mild alkaline compound used in cooking.
Caustic soda is prepared through the Chlor-Alkali process by electrolysis of sodium chloride (brine) solution: 2NaCl + 2H₂O → 2NaOH + Cl₂ + H₂
Caustic soda dissolves in water with a highly exothermic (heat-releasing) reaction: NaOH (s) → Na⁺ (aq) + OH⁻ (aq) + Heat This produces a strong alkaline solution.
The molecular mass of caustic soda (NaOH) is 40 g/mol, calculated as:
It is called “caustic” because it is highly corrosive and can cause severe burns to skin and tissue. “Soda” refers to its sodium content and alkaline nature.
A concentrated solution of caustic soda has a pH between 13-14, making it a very strong base.
Caustic soda is used in:
Yes, caustic soda is highly corrosive and dangerous. Safety precautions include:
Warning: Caustic soda is a hazardous chemical that requires careful handling:
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