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Acids and Bases

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Presentation on theme: "Acids and Bases"— Presentation transcript:

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2 Acids and Bases http://www.unit5.org/chemistry/AcidBase.html

3 http://www.chalkbored.com/lessons/chemistry-11/acid-bronsted.ppt

4 Properties electrolytes turn litmus red sour taste react with metals to form H 2 gas slippery feel turn litmus blue bitter taste ChemASAP vinegar, milk, soda, apples, citrus fruits ammonia, lye, antacid, baking soda electrolytes

5 Acid vs. Base Acid pH > 7 bitter taste does not react with metals pH < 7 sour taste react with metals Alike Different Related to H + (proton) concentration pH + pOH = 14 Affects pH and litmus paper Base Different Topic

6 Common Acids and Bases Strong Acids (strong electrolytes) HClhydrochloric acid HNO 3 nitric acid HClO 4 perchloric acid H 2 SO 4 sulfuric acid Weak Acids (weak electrolytes) CH 3 COOHacetic acid H 2 CO 3 carbonic Strong Bases (strong electrolytes) NaOH sodium hydroxide KOH potassium hydroxide Ca(OH) 2 calcium hydroxide Weak Base (weak electrolyte) NH 3 ammonia Kotz, Purcell, Chemistry & Chemical Reactivity 1991, page 145 Weak Base (weak electrolyte) NH 4 OH ammonia NH 3 + H 2 O  NH 4 OH

7 Common Acids Sulfuric AcidH 2 SO 4 Nitric AcidHNO 3 Phosphoric AcidH 3 PO 4 Hydrochloric AcidHCl Acetic Acid CH 3 COOH Carbonic Acid H 2 CO 3 Battery acid Used to make fertilizers and explosives Food flavoring Stomach acid Vinegar Carbonated water

8 Common Bases Sodium hydroxideNaOHlye or caustic soda Potassium hydroxideKOHlye or caustic potash Magnesium hydroxideMg(OH) 2 milk of magnesia Calcium hydroxideCa(OH) 2 slaked lime Ammonia waterNH 3 H 2 Ohousehold ammonia Name Formula Common Name. NH 4 OH NH 4 1+ + OH 1- ammonium hydroxide hydroxide ion OH 1-

9 Formation of Hydronium Ions 1+ hydronium ion H3O+H3O+ + hydrogen ion H+H+ water H2OH2O 1+ (a proton) 1+

10 Arrhenius Acid 1+ ++ hydronium ion H3O+H3O+ 1- chloride ion Cl - water H2OH2O hydrogen chloride HCl (an Arrhenius acid) Any substance that releases H + ions as the only positive ion in the aqueous solution.

11 Arrhenius Bases and Their Properties According to the definition of Arrhenius a: Base Base - "a substance whose water solution yields... Are NaOH and NH 3 considered to be Arrhenius bases? 1) Bases are electrolytes Dissociation equation for NH 3 NH 3 (g) + H 2 O(l) NH 4 1+ (aq) + OH 1- (aq) Dissociation equation for NaOH NaOH(s) Na 1+ (aq) + OH 1- (aq) indicators 2) Bases cause indicators to turn a characteristic color 3) Bases neutralize acids NaOH(aq) + HCl(aq) NaCl(aq) + H 2 O(l) YES 4) Water solutions of bases tasted bitter and feel slippery. hydroxide ions (OH - ) as the only negative ions."

12 Each of the following unbalanced equations represents a reaction between a Arrhenius acid and base. Identify those in each reaction: H 2 CO 3 + NH 4 OH → (NH 4 ) 2 CO 3 + H 2 O KOH + H 3 PO 4 → K 3 PO 4 + H 2 O HF + NaOH → NaF + H 2 O Ba(OH) 2 + HNO 2 → Ba(NO 2 ) 2 + H 2 O

13 Brønsted-Lowry Acids and Bases 1+ + hydronium ion H3O+H3O+ 1- chloride ion Cl - (base) H2OH2O (acid) HCl ++ -- Acid = any substance that donates a proton. Base = any substance that accepts a proton.

14 Brønsted-Lowry Acids and Bases 1+ + hydronium ion H3O+H3O+ 1- chloride ion Cl - (base) H2OH2O (acid) HCl ++ -- Acid = any substance that donates a proton. Base = any substance that accepts a proton.

15 Brønsted-Lowry Acids and Bases (acid) H2OH2O (base) NH 3 ++ -- 1+ + ammonium ion NH 4 + 1- hydroxide ion OH -

16 Identify the Bronsted-Lowry acid and the Bronsted-Lowry base in each reaction. NH 4 + (aq) + CN - (aq) → HCN (aq) + NH 3 (aq) (CH 3 ) 3 N(aq) + H 2 O → (CH 3 ) 3 NH + (aq) + OH - (aq) HCHO 2 (aq) + PO 4 3- → CHO 2 - (aq) + HPO 4 2- (aq) HSO 4 - (aq) + CO 3 2- → SO 4 2- (aq) + HCO 3 - (aq)

17 Definitions  Lewis AcidsAcids are electron pair acceptors. BasesBases are electron pair donors. Lewis base Lewis acid Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

18 Arrhenius Acids and Bases Acids release hydrogen ions in water. Bases release hydroxide ions in water. An acid is a substance that produces hydronium ions, H 3 O +, when dissolved in water. Lewis Definitions A Lewis acid is a substance than can accept (and share) an electron pair. A Lewis base is a substance than can donate (and share) an electron pair. Lewis Acid Brønsted-Lowry Definitions A Brønsted-Lowry acid is a proton donor; it donates a hydrogen ion, H +. A Brønsted-Lowry base is a proton acceptor; it accepts a hydrogen ion, H +. Brønsted-Lowry Arrhenius acids Acid Definitions

19 Lewis acids Brønsted-Lowry Arrhenius acids The Arrhenius model of acids and bases was broadened by the Brønsted-Lowry model. The Lewis acid-base model is the most general in scope. The Lewis definition of an acid includes any substance that is an electron pair acceptor; a Lewis base is any substance that can act as an electron pair donor. Ralph A. Burns, Fundamentals of Chemistry 1999, page 483

20 Lewis acids Brønsted-Lowry Arrhenius acids The Arrhenius model of acids and bases was broadened by the Brønsted-Lowry model. The Lewis acid-base model is the most general in scope. The Lewis definition of an acid includes any substance that is an electron pair acceptor; a Lewis base is any substance that can act as an electron pair donor. Ralph A. Burns, Fundamentals of Chemistry 1999, page 483 Acid Definitions

21 Acid – Base Systems TypeAcidBase ArrheniusH + or H 3 O + producer OH - producer Brønsted- Lowry Proton (H + ) donor Proton (H + ) acceptor LewisElectron-pair acceptor Electron-pair donor


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