Acids and Bases
pH scale Video click here)
Measures how acidic or basic a substance is ⭐
Ranges from pH 0 to pH 14
Ranges from Highly acidic to Highly basic (or alkaline)
Acids
Tastes sour
pH scale range below 7
Turn blue litmus paper red
Home examples include: lemon juice, vinegar and rain water
Bases
Turn red litmus paper blue
pH scale range above 7
Science Laboratory examples include: Hydrochloric acid (HCl) and Sulphuric acid (H2SO4)
Tastes bitter and are slippery
Home examples include: Toothpaste, drain cleaner, baking soda and bleach 
Science Laboratory examples include: Sodium hydroxide (NaOH) and Calcium hydroxide (also known as limewater)
pH 0 — pH 6.9 is acidic
pH 7 is neutral
pH 7.1 — 14 is basic
Acid-Base Indicators
Used to test if a substance is acidic or a basic by means of a colour change ⭐
Called Alkalis when dissolved in water
Examples include: Litmus paper or solution, methyl orange and universal indicator paper
Neutralisation
Definition: This is the reaction between an acid and a base ⭐
Acid + Base = Water + a Salt + Heat 🔥 Example: HCl + NaOH = NaCl and H2O
Real world examples
Antacid medicine for heart burn (Rennie)
Toothpaste used to neutralise acids in the mouth
Lime used on farms to neutralise the soil
Can be corrosive
Can be corrosive
Study of acid rain Video - click here
Acid rain has a pH of less than 5.5
Acid rain contains sulphuric acid and nitric acid that comes from Sulphur dioxide (SO2) and Nitrogen dioxide (NO2)
SO2 and NO2 come from burning of fossil fuels from factories and cars 
Effects of acid rain
Stone buildings and walls can be destroyed 
Fish can die 
Trees can die from acidified soil 
Natural acid-base indicators: Red cabbage and Hydrangeas
Litmus paper 
Universal indicator paper 
Methyl orange indicator
Acid is added to base - colour change from yellow-orange to brick red Titration example - Neutralisation reaction 
pH meters or sensors are the most accurate way to measure a pH of an acid or base 