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Acids and bases.

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Presentation on theme: "Acids and bases."— Presentation transcript:

1 Acids and bases

2 Properties of acids & bases

3 15-1 objectives List 5 general properties of aqueous acids and bases
Name common binary acids and oxyacids List 5 common industrial and laboratory acids and give 2 properties of each Define Arrhenius acids and bases Explain the difference between strong and weak acids and bases 4/24/2017

4 Properties of Acids Taste sour Change the color of pH indicators
(turn blue litmus paper red) React with active metals to produce hydrogen gas React with bases to produce salts and water Conduct an electric current 4/24/2017

5 Properties of Bases Taste bitter
Change the color of acid-base indicators (turn red litmus paper blue) Feel slippery React with acids to produce salts and water Conduct an electric current 4/24/2017

6 Commonly Used Acids Sulfuric acid (H2SO4)
dehydrating agent; batteries; metals, paper; dyes, paints & detergents Nitric acid (HNO3) stains proteins yellow; very smelly; explosives Phosphoric acid (H3PO4) fertilizer; ceramics; detergents; flavoring Hydrochloric acid (HCl) “pickling” metals; food processing; pools; cleaning masonry Acetic acid (CH3COOH) smelly; vinegar; freezes at 17oC; plastics; fungicide 4/24/2017

7 HNO3(l) + H2O(l)  H3O+(aq) + NO3-(aq)
Arrhenius Acid & Bases Arrhenius acid – increases the concentration of hydrogen ions in aqueous solution HNO3(l) + H2O(l)  H3O+(aq) + NO3-(aq) The H3O+ ion is called the hydronium ion Arrhenius base – increases the concentration of hydroxide ions in aqueous solutions 4/24/2017

8 Strong Acids Strong acids ionize completely in aqueous solutions and are strong electrolytes Examples: H2SO4 HClO4 HCl HNO3 HBr HI Do a few examples of showing this ionization process behind this. Demonstrate how the hydronium ion is formed. 4/24/2017

9 Weak Acids Do not ionize completely and are weak electrolytes
Examples: H3PO4 CH3COOH H2CO3 H2S HCN Clip These equations will go both ways. 4/24/2017

10 4/24/2017

11 Strong Bases A strong base completely dissociates in water to produce OH- ions Solutions are called alkaline Examples: NaOH KOH 4/24/2017

12 Weak Bases Weak bases do not dissociate completely in solution
Example: NH3 C6H5NH2 (aniline) Clip 4/24/2017

13 4/24/2017

14 Acid-Base Theories

15 15-2 Objectives Define and recognize Brønsted-Lowry acids and bases
Define a Lewis acid and a Lewis base Name compounds that are acids under the Lewis definition but are not acids under the Brønsted-Lowry definition 4/24/2017

16 Brønsted-Lowry Acids A molecule or ion that is a proton donor is Brønsted-Lowry acid Example: HCl dissolved in ammonia HCl dissolved in water H2O dissolved in ammonia Acids donate protons - Complete these three examples by writing out the equations. 4/24/2017

17 Brønsted-Lowry Bases A molecule or ion that accepts a proton is a Brønsted-Lowry base Example: HCl dissolved in ammonia Bases are proton acceptors 4/24/2017

18 HCl(g) + H2O(l)  H3O+(aq) + Cl-(aq)
Monoprotic Acids Monoprotic acids can donate only one proton Example: HCl(g) + H2O(l)  H3O+(aq) + Cl-(aq) 4/24/2017

19 4/24/2017

20 Polyprotic Acids Polyprotic acids can donate more than one proton
Example: H2SO4(l) + H2O(l)  H3O+(aq) + HSO4-(aq) HSO4-(aq) + H2O(l)  H3O+(aq) + SO42-(aq) This is a diprotic acid (2 ionizations) 4/24/2017

21 4/24/2017

22 Lewis Acids and Bases An atom, ion, or molecule that accepts an electron pair to form a covalent bond is a Lewis acid An atom, ion, or molecule that donates an electron pair to form a covalent bond is a Lewis base 4/24/2017

23 Acid-base reactions

24 15-3 Objectives Describe a conjugate acid, conjugate base, and amphoteric compound Explain the process of neutralization Explain how acid rain damages marble surfaces 4/24/2017

25 Amphoteric A molecule or ion that can be classified as an acid or a base. Ex HSO4- 4/24/2017

26 Conjugate Acids & Bases
The species that remains after a Brønsted-Lowry acid has given up a proton is the conjugate base of that acid. Example: 4/24/2017

27 Conjugate Acids & Bases
The species that is formed when a Brønsted-Lowry base gains a proton is the conjugate acid of that base. Example: 4/24/2017

28 Brønsted-Lowry acid-base reactions are equilibrium systems (can occur both forward and reverse) and involve two acid-base pairs known as conjugate acid-base pairs. 4/24/2017

29 Strength of Conjugate Acids and Bases
The stronger the acid is the weaker its conjugate base The stronger the base, the weaker its conjugate acid Students will read page 470 to be able to explain this to me. 4/24/2017

30 4/24/2017

31 Neutralization Reactions
Are reactions between hydronium ions and hydroxide ions to form water Another product is a salt – a cation from an acid and an anion from a base 4/24/2017


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