Grade 9 → Acids, Bases and Salts ↓
Properties of bases
Bases are an important class of chemical substances. They play a key role in various chemical reactions and have many applications in everyday life. In chemistry, understanding the properties of bases helps us identify and use them efficiently. In this explanation, we will explore the various properties of bases in detail, providing examples and simple explanations to make the concept easier to understand.
What are the bases?
Bases are chemicals that can accept hydrogen ions ( H +
) or, more commonly, donate a pair of valence electrons. They are usually identified by certain properties such as taste, feel, and their reactions with indicators and acids.
Physical properties of bases
Taste
Bases often taste bitter. This is one reason why foods such as baking soda and unsweetened chocolate (which contains bases) taste bitter. However, taste testing unknown substances in a laboratory is unsafe and should be avoided.
Feel
Bases can feel slippery or soapy to the touch. This is because they react with lipids in the skin to form soap-like compounds. An example of this is the slippery feeling of soap, which contains a basic substance called sodium hydroxide.
Example: When you wash your hands with soap, you may feel slippery. This is because soap contains a base that combines with the oils on your skin to form a soap-like compound, causing a slippery feeling.
Chemical properties of bases
Reaction with acids (neutralization)
Bases react with acids in a process called neutralization. This reaction forms salt and water. The general form of a neutralization reaction is:
Acid + Base → Salt + Water
For example, when hydrochloric acid ( HCl
) reacts with sodium hydroxide ( NaOH
), the products are sodium chloride ( NaCl
), a salt, and water ( H 2 O
):
HCl + NaOH → NaCl + H 2 O
Reacting with indicators
Bases change the colour of certain dyes called indicators. Indicators are substances that change colour when added to acidic or alkaline solutions. Some common indicators and their colour changes in the presence of bases are as follows:
- Litmus Paper: Under basic conditions, blue litmus paper stays blue while red litmus paper turns blue.
- Phenolphthalein: It turns pink in the presence of alkali.
- Bromothymol Blue: It turns blue under basic conditions.
Example: If you dip red litmus paper in sodium hydroxide solution it will turn blue, which indicates that the solution is alkaline.
Electrolytic nature
Bases are electrolytes, which means they can conduct electricity when dissolved in water. This happens because bases dissociate into ions, which are charged particles capable of carrying an electric current. This property makes them suitable for use in electrolytic cells and batteries.
Example: A solution of potassium hydroxide ( KOH
) in water can conduct electricity because KOH
dissociates into its component ions ( K +
and OH -
), making it possible for electrical charge to flow.
Alkalinity
Bases have a high pH level, usually greater than 7. The pH scale ranges from 0 to 14, with 7 being neutral. Solutions with a pH greater than 7 are alkaline or basic. The higher the pH, the more basic the solution.
Example: A solution of ammonia ( NH 3
) in water may have a pH of about 11, indicating that it is an alkaline solution.
Common examples of bases
There are many common ground that you may encounter in everyday life. Here are some examples:
- Sodium hydroxide (
NaOH
): Commonly known as caustic soda or lye, used in soap making. - Potassium hydroxide (
KOH
): Sometimes used to make liquid soap and as a fertilizer. - Ammonia (
NH 3
): Used in household cleaning products. - Calcium hydroxide (
Ca(OH) 2
): Known as slaked lime, it is used in construction and making cement. - Magnesium hydroxide (
Mg(OH) 2
): Known as milk of magnesia, used as an antacid.
Sodium hydroxide ( NaOH
)
Sodium hydroxide or NaOH
is one of the most common bases. It is used to make soap and paper and in chemical laboratories. It reacts easily with acids and is one of the strongest bases available.
Ammonia ( NH 3
)
Ammonia is a gas at room temperature and is commonly used in household cleaners. It is less corrosive than sodium hydroxide and has a distinctive, pungent odor. It can also be found in fertilizers due to its high nitrogen content.
Applications of bases
Bases have numerous applications in different fields, which is why they are essential in daily life.
In the industry
- Soap and detergent manufacturing: Sodium hydroxide is used to make soap. Potassium hydroxide is used in the production of liquid soap.
- Paper manufacturing: Sodium hydroxide is used in the paper industry to pulp wood and refine paper products.
- Textile industry: Alkalis help dye fabrics and improve color fastness.
- Food industry: Ammonium hydroxide is used as a pH control agent in food processing.
In medicine
- Antacids: Magnesium hydroxide and calcium carbonate are used to neutralise stomach acid and relieve heartburn.
- Cleaning agents: Many bases are used in antiseptic products and cleaning agents to kill germs and remove dirt.
Safety precautions with bases
Despite their beneficial uses, alkalis can be corrosive and dangerous if not handled properly. It is important to follow certain safety measures when working with alkalis.
Guidelines for safe operation
- Wear protective equipment such as gloves and goggles when working on strong bases.
- Use the base in a well-ventilated area to avoid fumes.
- In case of skin contact, wash area immediately with plenty of water.
- To prevent accidental reactions, store bases in labeled, appropriate containers away from acids.
By understanding and respecting the properties of bases, we can use them effectively while ensuring safety. This comprehensive overview of the properties and applications of bases provides information about their importance in both scientific and practical contexts.