1. Acids and Bases

2. Have you ever wondered, “Why do foods taste sour or bitter?”

3. It all depends on whether it is acidic or basic (alkaline)… Acids taste sour Bases taste bitter ACID OR BASE???

4. There are far more significant differences between acids and bases…

5. What is an ACID? - a substance that produces hydrogen ions (H + ) in a water solution. H 2 O H 2 O HCl  H + (aq) + Cl - (aq)

6. Properties of Acids - taste sour. - feel “squeaky” when you rub your fingers together. - change litmus paper to red. - become less acidic when mixed with bases. - strong acids are corrosive.

7. Examples of Acids Many of our foods are acidic: -lemons -oranges -oranges -tomato sauce -vinegar -vinegar-soda

8. Examples of Acids (continued) Other acids have everyday uses: -acetylsalicylic acid (aspirin) -nitric acid (fertilizers) -sulfuric acid (car batteries) -phosphoric acid (detergents)

9. What is a BASE? - a substance that produces hydroxide ions (OH - ) in a water solution. H 2 O H 2 O NaOH  Na + (aq) + OH - (aq)

10. Properties of Bases - taste bitter. - feel slippery. - change litmus paper to blue. - become less basic when mixed with acids. - strong bases are corrosive.

11. Examples of Bases Few foods are basic: -egg whites -baking powder -antacids

12. Examples of Bases (continued) Other bases have everyday uses: -ammonia (cleaner) -shampoo (cleaner) -dishwashing liquid (cleaner) -magnesium hydroxide (laxative) -aluminum hydroxide (water purification) -sodium hydroxide (drain cleaner)

13. WHAT REALLY HAPPENS Acids are compounds that break into hydrogen (H+) ions and another compound when placed in an aqueous (water) solution. Bases are compounds that break up into hydroxide (OH-) ions and another compound when placed in an aqueous (water) solution. If you have an ionic compound and you put it in water, it will break apart into two ions. If one of those ions is H+, the solution is acidic. If one of the ions is OH-, the solution is basic.

14. What is a SALT? -A salt is a compound formed when the negative ions from an acid combine with the positive ions from a base. acid + base  salt + water

15. Salts (continued) Salts (continued) Neutralization: -chemical reaction between an acid and a base in water. -when you mix an equal amount of acids and bases to cancel each other out, you make salt water.

16. Examples of Salts We encounter salts in our everyday life: -sodium chloride (table salt) -calcium carbonate (chalk) -sodium hydrogen carbonate (baking soda)

17. What is pH? -the measure of the concentration of H + ions in it. -the greater the H + concentration, the lower the pH and the more acidic the solution is. -the lower the H + concentration, the higher the pH and the more basic (alkaline) the solution is.

18. The pH scale is actually a measure of the number of H+ ions in a solution. If there are a lot of H+ ions, the pH is very low. If there are a lot of OH- ions, that means the number of H+ ions is very low, so the pH is high.

19. pH Scale -a scale ranging from below 0 to above 14. -solutions with pH lower than 7 are acidic. -solutions with pH greater than 7 are basic. -solutions with pH equal to 7 are neutral.

20. Rain -Normally, rain is slightly acidic and mixes with natural chemicals in the air and the soil to balance out (neutralize). -The result is a pH between 6 and 8.

21. Acid Rain - However, when pollutants are introduced, this balance is upset. -The burning of fossil fuels releases sulfur dioxide and nitrogen oxides into the air. -The result is the formation of sulfuric acid and nitric acid (pH less than 5.6). -Acid rain can kill plants, damage buildings, and cause asthma and other physical problems.

22. THE THE END END