Acids, Bases, and pH Overview: Lessons, Definitions, and Reactions

1. Acids, Bases, pH, & Neutralization

2. Overview of Lesson #7 – Acids and Bases • Acids are compounds that break into ___________________and another compound when placed in an aqueous solution. • Bases are compounds that break up into _________________and another compound when placed in an aqueous solution

3. Overview of Lesson #7 – Acids and Bases • That pH scale we talked about is actually a measure • 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.

4. Overview of Lesson #7 – Acids and Bases

5. Overview of Lesson #7 – Acids and Bases • The hydronium ion:

6. Names to Know • ______:A solution that has an excess of H+ ions. It comes from the Latin word acidus that means "sharp" or "sour". ________:A solution that has an excess of OH- ions. Another word for base is alkali.___________:A solution that is mainly water. Think about the word aquarium. AQUA means water. _____________:An acid that has a very low pH (0-4).____________:A base that has a very high pH (10-14). ____________:An acid that only partially ionizes in an aqueous solution. That means not every molecule breaks apart. They usually have a pH close to 7 (3-6). _______________:A base that only partially ionizes in an aqueous solution. That means not every molecule breaks apart. They usually have a pH close to 7 (8-10). ___________:A solution that has a pH of 7. It is neither acidic nor basic

7. The dissociation in H2O • Complete the dissociations in water: • HCI • HNO3 • Ca(OH)2 • Al(OH)3 • http://www.youtube.com/watch?v=u9nOIZDdvRw&feature=related

8. Why are some acids or bases better electrolytes than others? • From our lab, what was more acidic, HCI, lemon juice? • What about NaOH? • Which one was a stronger electrolyte? • How is this related to pH? Strong or weak acids/bases? • Figure 10.1, pg. 371

9. Strong and Weak Acids and Bases • An acid that dissociates completely into ions in water = • Eg. HCl: when HCl molecules enter solution, 100% dissociate. Figure 10.6, pg. 381 • This solution contains the same percent of H+ (H30+) and Cl-ions: 100% Eg. 1.0mol/L solution of HCl contains 1.0mol/L of hydronium ions.

10. Some Strong Acids / Bases http://www.youtube.com/watch?v=WnPrtYUKke8

11. Weak Acids • Acid that dissolves slightly in water = • Eg. Acetic acid: only 1% of molecules dissociate in 0.1mol/L solution • Figure 10.7, pp. 382 • Weak acids dissociate _____________, they re-associate at the same time and rate.

12. # of Dissociations • Mono, di, tri – protic acids • Eg. Pp. 382-83 • The acid formed by the first dissociation is stronger than that of the second, etc.

13. Strong and Weak Bases • Same theory, using OH- instead of H3O+

14. Naming Acids

18. Try it out! • H2SO4 • HI • H2SO4 • Sulfuric Acid • Chlorous Acid • Carbonic Acid

19. pH – Hydrogen in Water • At 25o, about 2 molecules of water in a billion are dissociated. • Pure water is a poor conductor

20. Neutral, Acidic, Basic

21. pH = power of 10 x [H+] • The concept of pH allows [H30+] to be expressed as a positive number • See table 10.7, pp. 387

22. pH Scale

23. Neutralization Reaction http://www.youtube.com/watch?v=8IRI5gPR5EY

24. Salts from Acids • Eg. Sodium Nitrate: used to preserve meats • Can be made in lab by reacting nitric acid with sodium hydroxide • 1 mol with 1 mol

25. How do you know this is happening? • Acid/base indicators • Changes colour in acidic and basic solutions

26. Acid Rain • http://www.youtube.com/watch?v=HE6Y0iEuXMQ • http://www.youtube.com/watch?v=Nc6j7zz1_do&feature=related

27. Acid Rain