2.  Why do vinegar or lemon juice taste sour?  They are Acids!  The term acid comes from the Latin term acere, which means “sour”  In the 17 th century, chemist Robert Boyle first labeled substances as acids or bases according to certain characteristics.  1 st reasonable definition for acids and bases was not proposed until the 19 th century, with Swedish scientist Svante Arrhenius

3.  Stated that Acids contained Hydrogen and release hydrogens into solution  Bases release OH- (Hydroxide Ions) into solution.  Acids and Bases can combine to neutralize, or counteract each other.

4.  Acids in the home  Dilute weak acids  Have a sour taste  Safe to use in food, but can still hurt if they get into a cut or eyes  Examples  Vinegar = Ethanoic Acid  Fizzy Drinks (Soda) = Carbonic Acid  Tea = Tannic Acid  Vitamin C = Ascorbic Acid  Lemons = Citric Acid

5.  React with oils and fats  Often used in strong household cleaners  Examples  Drain cleaners and oven cleaners contain Sodium Hydroxide  Ammonia is also used in cleaners  Wise to wear gloves with these substances because it will burn skin!  Weak bases are found in toothpaste, antacid tablets (help to cure an upset stomach) and baking powder

6.  Indicator: substance that can change color when they are added to acidic or alkaline/basic solutions  You can prepare your own homemade indicators  Two commonly used indicators  Litmus paper  Universal indicator

7. Red LitmusBlue Litmus Acidic SolutionStays RedTurns Red Neutral SolutionStays RedStays Blue Alkaline/Basic SolutionTurns BlueStays Blue

8.  Is a mixture of several different indicators  It shows us EXACTLY how strongly acidic or alkaline/basic a solution is  Measured using the PH Scale, which runs from 0 to 14  Has many different colors, from red for strong acids to dark purple for strong bases. In the middle, neutral pH 7 is indicated by green.

9.  Neutral solutions have a pH of 7  Acidic solutions have a pH less than 7  Basic solutions have pH values more than 7  The closer to pH 0 you go, the more strongly acidic  The closer to pH 14 you go, the more strongly alkaline/basic