UNIT OVERVIEW

This unit explores reactions that happen in water. Many important substances around you are aqueous solutions—your blood, the ocean, cleaning products, and the drinks you consume. Understanding how substances behave when dissolved in water is essential for chemistry.

When you dissolve table salt in water, the salt breaks apart into particles called ions that can conduct electricity. When you mix certain solutions together, a solid might suddenly appear. These are the types of reactions you will study in this unit.

In this unit, you will learn:

• How ionic compounds behave when dissolved in water
• Why some solutions conduct electricity while others do not
• How to predict when a precipitate (solid) will form
• The difference between electrolytes and non-electrolytes
• How to write ionic equations for reactions in solution
• The four main types of chemical reactions: precipitation, gas-forming, acid-base, and redox

Real-life applications:

1. Water purification plants — Precipitation reactions remove harmful metal ions from drinking water
2. Antacid tablets — An acid-base reaction neutralises excess stomach acid
3. Car batteries — The sulfuric acid solution conducts electricity because it contains ions
4. Swimming pool chemistry — Chlorine compounds dissociate in water to kill bacteria
5. Medical IV drips — Saline solution (NaCl in water) contains ions that help maintain electrolyte balance

---