1. Acids & Bases 2 Chapter 28

2. Objectives 1.Outline of common laboratory acids and bases 2.Be able to name some common lab acids and bases 3.Examine how acids and bases react in a neutralisation reaction 4.To look at some examples of neutralisation in everyday life. 5.To examine how salts are formed 6.To study a simple neutralisation reaction

3. Properties of acids and bases: 1.They affect the colour of indicators 2.Bases which dissolve in water are called alkalis 3.The pH scale gives an indication of the level of acidity or basicity of a solution

4. Common lab acids and bases Acids:Hydrochloric AcidHCl Sulfuric Acid H 2 SO 4 Safety Symbols: Corrosive Keep acids away from skin, eyes etc. Bases: Sodium Hydroxide NaOH (commonly called caustic soda) Used to clear blocked drains Safety Symbol: Corrosive

5. Calcium Hydroxide Ca(OH) 2 A solution of Calcium Hydroxide in water is called limewater. Limewater is the chemical used to test for the presence of carbon dioxide in air. (lime water turns milky if CO 2 Present)

6. Reaction of Acid + Base = neutralisation Antacid = against acid Antacid is often written on medicine For people with indigestion Problems. If a person has too much HCl acid in their stomach they have indigestion if they take an antacid tablet it neutralise the acid and the indigestion goes away.

7. Examples of neutralisation in everyday life 1.Toothpaste (a base) neutralises the acid on your teeth. 2.Baking soda (base) neutralises a bee sting (acid) 3.Vinegar (acid) neutralises a wasp sting (base) Remember: Vinegar for vasp stings

8. Formation of Salts When acid plus base neutralise each other you get: Acid + Base = Salt + water What is a salt? A salt is formed when the hydrogen in an acid is replaced by a metal