Acid and Bases Chapter 24

Examples of Everyday Acids and Bases Lemon Juice Vinegar Stomach Acid (HCl) Rain water Toothpaste Window Cleaner Toilet Bleach Baking Soda

Litmus Paper Litmus paper can be used to tell if something is an acid, base or neutral. Acid Neutral Base Red stays red. Blue turns red. Blue stays blue. Red turns blue.

The pH Scale The pH scale is a scale used to measured how acidic or basic something is. Acids have a pH of less than 7 (1 to 6). Neutral substances (e.g. water) have a pH of 7. Bases have a pH of greater than 7 (8 to 14). Universal indicator paper can be used to find the pH of a substance.

Alkaline An alkali is a base which dissolves in water. Example: toothpaste We say the substance is alkaline.

Acids and Bases – Chapter 28 Acids and Bases in the Lab STRONG ACIDS STRONG BASES Hydrochloric Acid HCl Sulfuric Acid H2SO4 Sodium Hydroxide NaOH Calcium Hydroxide (Limewater) Ca(OH)2 Calcium Carbonate CaCO3

Neutralisation Neutralisation occurs when an acid and a base react to make something which is neutral (pH 7) Examples of neutralisation reactions: Putting vinegar (acid) on a wasp sting (basic) Taking antacid tablets (bases) to neutralise excess stomach acid

Indicators To show that neutralisation has occurred we use an indicator. An indicator is any substance which can show whether something is an acid or a base by changing colour. Examples of indicators: Litmus Paper – red in acid, blue in base Universal indicator paper - changes colour depending on pH Methyl Orange – turns form orange to pink when neutralisation occurs.

Neutralisation Reactions When acids and bases neutralise each other they make a salt and water. Reaction: Acid + Base Salt + Water Hydrochloric + Sodium Sodium + Water Acid Hydroxide Chloride HCl + NaOH NaCl + H2O Hydrochloric + Calcium Calcium + Water + Carbon Acid Carbonate Chloride Dioxide 2 HCl + CaCO3 CaCl2 + H2O + CO2

Titration Reaction Titrating Hydrochloric Acid Against A titration involves measuring the exact volume of acid and base needed to react to make a neutral substance. Titrating Hydrochloric Acid Against Sodium Hydroxide Indicator Used: Methyl Orange Hydrochloric

What you need to know: Chapter 24 Chapter 28