CHEMISTRY EXAM SEASON - TERM 3

ACIDS,BASES AND SALTS

Acids

Acids are chemical substances that realease H+ Acids when dissolved in water , They can also conduct in water

H+ is responsible for characteristic properties of acids, such as their sour taste and their ability to conduct electricity.

Bases

A Base is a chemical substance that can neutralise acids, While all alkalis are bases, not all bases are soluble in water. A base that does dissolve in water is specifically called an alkali. Bases realise OH-

OH- is responsible for charecteristic properties of bases, the slippery, soapy feel of alkaline solutions.

Neutralisation

Occurs when an acid and a base this happens because the hydrogen ions (H+) from the acid combine with the hydroxide ions (OH−) from the base to form water.

ACID + BASE = Salt + Water

Salt Formation

Salt formation 🧂 occurs when the "leftover" parts of the acid and base combine after the H+ and OH− ions have formed water

PROPERTIES OF COMMON SALTS

  • High Melting and Boiling Points: Salts are held together by strong electrostatic forces between oppositely charged ions. It takes a huge amount of energy to break these bonds, which is why most salts are solids at room temperature.

  • Solubility: Many salts dissolve easily in water. When they do, the crystal lattice breaks apart, and the ions become free to move.

  • Electrical Conductivity:

    • In solid form, salts do not conduct electricity because the ions are locked in place.

    • In molten (melted) or aqueous (dissolved in water) form, they do conduct electricity because the ions are free to carry a charge. ⚡️

REAL WORLD USES OF ACIDS,BASES AND SALTS

  • Acids 🍋

    • Food Preservation: Citric acid and acetic acid (vinegar) prevent bacteria from growing in food.

    • Digestion: Hydrochloric acid (HCl) in your stomach breaks down proteins and kills germs.

  • Bases 🧼

    • Cleaning: Sodium hydroxide (caustic soda) is used in drain cleaners to dissolve grease and hair.

    • Medicine: Antacids (like magnesium hydroxide) are mild bases used to neutralise excess stomach acid to relieve heartburn.

  • Salts 🧂

    • Agriculture: Ammonium nitrate is used as a fertilizer to provide plants with essential nitrogen.

    • De-icing: Sodium chloride or calcium chloride is spread on roads in winter to lower the freezing point of water, melting the ice.