Water (Junior Cert Home Economics): Revision Notes

Water

Composition of Water

• Water is made of two hydrogen (H) atoms and one oxygen (O) atom, represented by the formula H₂O.
• It is a 2:1 ratio of hydrogen to oxygen.

---

Properties of Water

• Boils at 100°C and freezes at 0°C.

  • Exists in three states:
  • Solid (ice)
  • Liquid (water)
  • Gas (vapour/steam)

• Pure water is tasteless, colourless, and odourless.

• Many substances dissolve easily in water (e.g., salt, sugar).

---

Sources of Water

• Food:
  • Most foods, except fats and dried foods (e.g., flour, sugar), contain water.
  • Fruits and vegetables have a high water content (e.g., strawberries are 91% water).
• Drinks:
  • Water, milk, juices, tea, coffee.

---

Functions of Water

1. Essential for all body tissues and fluids (e.g., blood).
2. Transports nutrients and oxygen to cells.
3. Removes waste products through urine.
4. Regulates body temperature via perspiration (sweat).

---

Dehydration

• What it is:
  • Occurs when the body loses more water than it takes in.
  • Common after vomiting, diarrhoea, or consuming too much alcohol.
• Symptoms:
  • Dry mouth, bad breath, headache.
  • Low blood pressure, dizziness.
• Dangers:
  • Particularly risky for babies and older adults.

---

Key Takeaway

• Our bodies are 70% water, and we lose 2–2.5 litres daily through sweat and urination.
• To stay hydrated, drink 2 litres (8 glasses) of fluids daily and eat water-rich foods.