Acids, Bases, & Salts

Acids  Acid= any compound that increases the number of hydrogen ions (H + ) (H 3 O + )when dissolved in water  Tastes sour  Changes color of certain compounds  pH of 0-6  Corrosive (destroy body tissue or clothing)  Conduct electric current

Examples of acids:  Orange juice  Lemons  Limes  Acid rain  Soft drinks (soda)

Strong VS Weak acids  When all the molecules of an acid break apart= strong acid  When few molecules of an acid break apart= weak acid

Base  Base= any compound that increases the number of hydroxide ions (OH - )when dissolved in water  Tastes bitter  Slippery-Dissolves skin  Change colors with certain compounds  pH of 8-14  Conduct electric currents

Examples of Bases:  Soap  Ammonia  Sea water  Detergent

Strong VS Weak Bases  When all the molecules of a base break apart= strong base  When few molecules in a base break apart= weak base

Acids & Bases Neutralize One Another  Antacid= weak base to help soothe an acidic stomach or heart burn  Neutralize one another since H + and OH - form H 2 O which is water!!!!

How to detect an acid or base?  Indicator= substance that changes color in the presence of an acid or base  Example: litmus paper Blue litmus paper turns red for an acid Red litmus paper turns blue for a base

pH scale  pH= measure of the hydronium ion (H 3 O + ) and hydrogen ion (H + )of a solution  pH of an acid= less than 7  pH of a base= greater than 7  pH of neutral substances= 7

pH scale

Why is pH important?  Living things depend on stable pH’s  Fish like 7  Plants like 8-9  Pine trees like 4-6  Rainwater likes 3 or below

Salts  Salt= ionic compound formed form the positive ion of a base and the negative ion of an acid

Why do we need salts?  Salt for your food  Rock salt  Baking soda  Plaster board  Chalk  Limestone  Sea shells

Review Questions! 1. What ion is present in all acid solutions? 2. What are 2 ways scientists can measure pH? 3. What products are formed when an acid and base react? 4. Compare acids and bases. 5. What would you expect the pH of soap to be: 4 or 9?