Physical Science Chapter 9.2

 Create a sour taste in foods (lemons)  React with metals to produce hydrogen gas (H 2 )  Change color of blue litmus paper to red  Can be very corrosive, destroying metals and burning skin through chemical reactions

Acids make hydronium ions when dissolved in water  Hydronium ions (H 3 O + )

 Create a bitter taste  Have a slippery feel, like soap  Change the color of red litmus paper to blue  Can be very corrosive, destroying metals and burning skin through a chemical reaction

 Bases produce hydroxide ions when dissolved in water  Hydroxide ions (OH - )  aka Alkaline

 Strong Acid ◦ Hydrochloric Acid (HCl) ◦ Completely dissolves into H + ions  Weak Acid ◦ Acetic Acid (HC 2 H 3 O 2 ) ◦ Only as small percentage break apart into H + ions  Strong Base ◦ Sodium Hydroxide (NaOH) ◦ Dissociates completely to NA + and OH -  Weak Base ◦ Ammonia (NH 3 ) ◦ Only a few molecules react to form NH 4 + and OH -

 A Weak Acid  In presence of acid, it acts as a base  A Weak Base  In presence of base, it acts as an acid

 Potential for Hydrogen  pH scale 0-14  <7 is acid  0 is strong acid  >7 base  14 is strong base  7 is neutral

 Chemicals that turn different colors when exposed to acids or bases.  Red cabbage juice  Litmus paper ◦ Made from lichens ◦ Blue turns red with acids ◦ Red turns blue with bases  pH paper ◦ Tests both acids and bases

 Plants require specific range of pH, 5-7  Some plants change color based on pH, hydrangea ◦ Blue in acid soil ◦ Cream in neutral soil ◦ Pink/purple in alkaline soil  Ponds, etc. range of 6-8  Most fish tolerate 5-9  Most amphibians tolerate 6-8

 Stomach acid (pH 1.4) protected by mucus lining ◦ Ulcer, heartburn  Blood pH  Too much CO 2 makes blood acidic, regulate CO 2 level by automatic breathing changes

 When you mix an acid and a base, they neutralize each other, making water and a salt  Sodium bicarbonate and an upset stomach