What are the Properties and Common Uses of Sodium Hydroxide?
Sodium hydroxide is essential in chemistry and helps students understand various practical and theoretical applications related to this topic.
What is Sodium Hydroxide in Chemistry?
A sodium hydroxide is a highly caustic, white, inorganic base with the chemical formula NaOH. This concept appears in chapters related to acids and bases, properties of acids and bases, and chemical reactions, making it a foundational part of your chemistry syllabus.
Molecular Formula and Composition
The molecular formula of sodium hydroxide is NaOH. It consists of one sodium atom (Na), one oxygen atom (O), and one hydrogen atom (H). It is categorized under strong bases (alkali) and is known by other names like caustic soda and lye.
Preparation and Synthesis Methods
Sodium hydroxide is mainly produced industrially by the electrolysis of brine (saltwater) in the Chloralkali process. In the lab, it can be prepared by reacting sodium carbonate with calcium hydroxide, or through displacement reactions with sodium metal and water.
Physical Properties of Sodium Hydroxide
Sodium hydroxide appears as a white, odorless, crystalline solid. It is highly soluble in water, releasing heat (exothermic) when dissolving. Major properties include:
| Property | Value |
|---|---|
| Appearance | White crystalline solid |
| Molar Mass | 40 g/mol |
| Melting Point | 323 °C |
| Boiling Point | 1388 °C |
| Solubility in Water | High, exothermic |
| pH (in 5% solution) | 14 |
| Density | 2.13 g/cm³ |
| Odor | Odorless |
Chemical Properties and Reactions
Sodium hydroxide is a strong base and reacts vigorously with acids to form salts and water (neutralisation). It decomposes some organic materials and reacts with metals and amphoteric oxides. For example:
1. **Neutralisation:** NaOH + HCl → NaCl + H2O2. **Saponification:** NaOH + fat → Soap + Glycerol
3. It corrodes aluminum, zinc, and some other metals, releasing hydrogen gas.
Frequent Related Errors
- Confusing sodium hydroxide with sodium hypochlorite (bleach).
- Mixing up the products of neutralisation (salt + water, not just water).
- Not recognizing it as a strong base due to lack of odor or color.
- Overlooking exothermic nature—adding water too quickly.
Uses of Sodium Hydroxide in Real Life
Sodium hydroxide is widely used in industries like soap-making, paper manufacturing, textiles, petroleum refining, and food processing. At home, it's present in drain cleaners and oven cleaners. It is also essential in lab experiments involving titrations and neutralisation reactions.
Relation with Other Chemistry Concepts
Sodium hydroxide is closely related to topics such as properties of acids and bases and neutralisation reactions, helping students build a bridge between topics like pH, salts, and chemical reactions.
Step-by-Step Reaction Example
1. Take dilute sodium hydroxide (NaOH) solution in a beaker.2. Slowly add hydrochloric acid (HCl) with stirring.
3. Observe temperature rise (exothermic).
4. The reaction is: NaOH + HCl → NaCl + H2O
5. The resulting mixture is tested with litmus—turns neutral (pH ~7).
Lab or Experimental Tips
Always add sodium hydroxide pellets to water slowly, never the reverse, as the mixture can splatter due to rapid heat release. Vedantu educators always stress using gloves and goggles in their online demonstrations involving NaOH.
Try This Yourself
- Write the IUPAC name of NaOH.
- Classify sodium hydroxide as an acid or base.
- Give two real-life products that contain sodium hydroxide.
Final Wrap-Up
We explored sodium hydroxide—its structure, properties, reactions, and real-life importance. For more in-depth explanations and exam-prep tips, explore live classes and notes on Vedantu.
Acids Bases and Salts
Neutralisation Reaction
Properties of Acids and Bases
Hydrocarbons
FAQs on Sodium Hydroxide (NaOH): Properties, Uses, and Safety Precautions
1. What is sodium hydroxide and what is its chemical formula?
Sodium hydroxide is a powerful inorganic base with the chemical formula NaOH. It is also known as caustic soda or lye and is widely used in industries, laboratories, and cleaning applications.
2. Is sodium hydroxide an acid or a base?
Sodium hydroxide is a strong base (alkali). It dissociates completely in water to produce hydroxide ions (OH−), making the solution highly alkaline (pH ≈ 14).
3. What are the uses of sodium hydroxide?
Sodium hydroxide has a wide range of applications in daily life and industry, including:
- Soap making: Reacts with oils and fats in saponification
- Paper manufacturing: Used in the pulping process
- Cleaning agents: Found in drain and oven cleaners
- Textile industry: Used in fabric processing and dyeing
- Food processing: Used in peeling fruits and vegetables
4. Is sodium hydroxide harmful to humans?
Yes, sodium hydroxide is highly caustic and dangerous if mishandled. Exposure can cause:
- Severe skin and eye burns
- Damage to respiratory tract if inhaled
- Gastrointestinal injury if ingested
- Always use gloves, goggles, and handle in well-ventilated areas
5. What is the pH value of a sodium hydroxide solution?
Sodium hydroxide solution has a pH between 13–14, signifying it is a strong alkali with high hydroxide ion concentration.
6. How is sodium hydroxide prepared industrially?
Sodium hydroxide is prepared by the Chloralkali process:
- Brine (sodium chloride solution) is electrolyzed
- Produces sodium hydroxide, chlorine gas, and hydrogen gas
- Products are separated and purified for commercial use
7. Is sodium hydroxide the same as bleach?
No, sodium hydroxide and bleach are different chemicals.
- Sodium hydroxide (NaOH): Strong base used for cleaning, soap making, and various industries
- Bleach: Commonly refers to sodium hypochlorite (NaOCl), a strong oxidizing agent used for disinfection
8. Why is sodium hydroxide used in soap making?
Sodium hydroxide is essential for saponification, the process by which fats or oils react with NaOH to create soap and glycerin. This reaction forms the basis of most traditional and industrial soaps.
9. What safety precautions should you take while handling sodium hydroxide?
To safely handle sodium hydroxide:
- Wear gloves, safety goggles, and a lab coat
- Work in a well-ventilated area
- Avoid direct contact with skin, eyes, or ingestion
- In case of contact, rinse the area with plenty of water and seek medical help immediately
10. Can sodium hydroxide be found naturally?
No, sodium hydroxide does not occur free in nature. Due to its high reactivity, it is always manufactured industrially, usually from the electrolysis of brine (salt solution).
11. How do you neutralise sodium hydroxide safely?
To neutralise sodium hydroxide:
- Add a weak acid (like vinegar) slowly to the solution
- Stir gently and use small quantities at a time
- Always add acid to base, never base to acid
- Check neutrality using pH paper or indicator
12. What happens when sodium hydroxide reacts with hydrochloric acid?
Sodium hydroxide reacts with hydrochloric acid to undergo neutralisation:
NaOH (aq) + HCl (aq) → NaCl (aq) + H2O (l)
This forms sodium chloride (table salt) and water.
