2. Chapter 15 Acids and Bases

4. Examples of acids: Vinegar Lemon Juice Soft Drink Battery Acid Stomach Acid Apple Juice Black Tea

5. ACIDS produce solutions that: Taste sour Turn blue litmus paper red Conduct electricity React with metals to liberate a hydrogen gas Are corrosive (acid rain) React with bases to form salt and water

6. Examples of bases: Detergent Baking Soda Drain Cleaner Ammonia Soaps (hand, dish) Antacid

7. Bases produce solutions that: taste bitter turn red litmus blue conduct electricity feel slippery are corrosive (basic solution in glass container) reacts with acids to form salt and water

8. There are three common acid-base theories: the Arrhenius theory the Bronsted-Lowry theory the Lewis theory

9. THEORYACID DEFINITIONBASE DEFINITION Arrhenius Theory Bronsted-Lowry Theory Lewis Theory Any substance which releases H+ ion in water solution. Any substance which donates a proton/hydrogen ion. Any substance which can accept an electron pair. Any substance which releases OH- ions in water solution. Any substance which accepts a proton/hydrogen ion. Any substance which can donate an electron pair.

10. Svante Arrhenius was a Swedish chemist. In 1887, he published a paper concerning acids and bases. He concluded that solutions with acids and bases in them released particles when dissolved. He concluded that acids were substance which separated (ionized) in water solution to produce hydrogen ions (H+, or free protons). He also believed that bases were substance which ionized to produce hydroxide ions (OH-) in water solution.

11. Acid/Base reactions: Neutralization Produce water and a salt (and sometimes carbon dioxide). Hint: concentrate on the water first. Remember, water has the formula HOH. Complete and balance the following: HCl + KOH  HCl + Ca(OH) 2  HOH + KCl 2 Require equal numbers 2HOH + CaCl 2

12. 1. Ba(OH) 2 + H 3 PO 4  2. HC 2 H 3 O 2 + NaOH  3. H 2 SO 4 + KOH  4. H 2 CO 3 + NaOH  5. Na 2 CO 3 + HCl 

13. T. M. Lowry was an English scientist, while J. N. Bronsted was a Danish scientist. In 1923, they independently proposed a new definition of the terms acid and base. They stated that in a chemical reaction, any substance which donates a proton/hydrogen ion is an acid and any substance which accepts a proton/hydrogen ion is a base. Bronsted Lowry

14. HF + H 2 O  F - + H 3 O + Acid Base Conjugate Conjugate BaseAcid Acids lose a hydrogen to become a conjugate base Bases gain a hydrogen to become a conjugate acid Conjugates:

15. Example: Determine the acid, base, conjugate acid, and conjugate base in each of the following equations: HCl + H 2 O  Cl - + H 3 O + Acid Base Conjugate Conjugate Base Acid H 2 SO 4 + H 2 O  HSO 4 - + H 3 O + Acid Base Conjugate Conjugate Base Acid NH 3 + H 2 O  OH - + NH 4 + Base AcidConjugate Base Conjugate Acid

16. What is the conjugate base of the following substances? a.H 2 O ________________ b.NH 4 + ________________ c.HNO 2 _______________ d.HC 2 H 3 O 2 _________________ 3. What is the conjugate acid of the following substances? a.HCO 3 - __________________ b.H 2 O____________ c.HPO 4 2- ____________ d.NH 3 ___________

17. Gilbert Newton Lewis was and American chemist. In 1923, proposed an even broader definition of acids and bases. Lewis focused on electron transfer instead of proton transfer. He defined and acid as an electron-pair acceptor, and a base as an electron-pair donor. This definition applies to solutions and reactions which do not even involve hydrogen or hydrogen ions. His theory is used in organic chemistry.

18. Strong and Weak Acids/Bases The strength of an acid (or base) is determined by the amount of IONIZATION.

19. Strong Acids/Bases: an acid that ionizes (separates into ions) completely or very nearly completely in aqueous solutions Weak Acids/Bases: an acid that ionizes only slightly in dilute aqueous solutions My uncle was a chemist, a chemist he's no more for what he thought was H 2 O was H 2 S O 4. (Ha Ha) Strong and Weak Acids/Bases

20. HA Let’s examine the behavior of an acid, HA, in aqueous solution. What happens to the HA molecules in solution?

21. HA H+H+ A-A- Strong Acid 100% dissociation of HA Would the solution be conductive?

22. HA H+H+ A-A- Weak Acid Partial dissociation of HA Would the solution be conductive?

23. HA H+H+ A-A- Weak Acid HA  H + + A - At any one time, only a fraction of the molecules are dissociated.

24. Strong Acids: Perchloric HClO4 Chloric, HClO 3 Hydrobromic, HBr Hydrochloric, HCl Hydroiodic, HI Nitric, HNO 3 Sulfuric, H 2 SO 4 Strong Acids: 100% ionized (completely dissociated) in water. HCl + H 2 O  H 3 O + + Cl -

25. What is a strong Base? A base that is completely dissociated in water (highly soluble). NaOH(s)  Na + + OH - Strong Bases: Group 1A metal hydroxides (LiOH, NaOH, KOH, RbOH, CsOH) Heavy Group 2A metal hydroxides [Ca(OH) 2, Sr(OH) 2, and Ba(OH) 2 ]

26. Weak Acids: “The Rest”