Unit 12: Acids & Bases. Aim: What are the definitions and properties of an acid and a base? Properties of an Acid. Taste Sour.

Transcription

1 Unit 12: Acids & Bases Aim: What are the definitions and properties of an acid and a base? Mar 23 12:08 PM Properties of an Acid 3. Are electrolytes. (Dissociate and conduct electricity when aq) 2. Turns Litmus Red 5. Taste Sour 7. Reacts with a metal to form H 2 (g) Neutralizes a base to produce a salt and H 2 O 1. ph is less than 7 Caustic and Corrosive Click and reveal 3 1

2 Jan 23 12:38 PM Properties of an Acid Acids will react with most metals to yield hydrogen gas through a single replacement reaction. Ta w Mar 23 1:31 PM 2

3 Properties of an Acid Acids usually have an "H" in the beginning of the formula except for acetic acid, CH 3 COOH. Mar 23 1:31 PM Properties of a Base 1. Are electrolytes. Dissociate and conduct electricity when (aq) 4. Turns Litmus Blue 5. Tastes Bitter 7. Slippery 2. Neutralizes an acid to produce a salt and H 2 O 3. ph is greater than 7 6. Caustic Click and reveal 3 3

4 Jan 23 12:39 PM Properties of a Base Bases will have a metal with an OH ion attached EXCEPT for ammonia, NH 3. BEWARE of the Imposters! CH 3 OH Mar 23 1:50 PM 4

5 1) Ionic made up of a metal and a nonmetal OR polyatomic ions. 2) ph= 7, neutral. Properties of a Salt 3) All salts are electrolytes because they dissociate into ions. All salt solutions contain mobile ions and conduct. Also conduct when molten because ions become mobile. 4) Salts will form during neutralization reactions between an acid and a base. Mar 23 2:10 PM Acid and Base Theories and Electrolytes Aim: What are the differences between the Arrhenius and Alternate (Bronsted) acid base theories? Mar 23 12:08 PM 5

6 Dissolving vs. Dissociation Mar 25 9:01 PM Electrolytes Electrolyte a substance that when aqueous dissociates and conducts electricity due to the presence of mobile ions. ACIDS, BASES and SALTS are electrolytes. The stronger the acid (most protonation of H + ions), the better it conducts electricity. Table K gives some of the strongest and best conducting acids. Mar 23 1:54 PM 6

7 Non Electrolytes If a compound does not produce ions in solution it is a nonelectrolyte. Covalent compounds, molecular solids, are nonelectrolytes and do not break up into ions solution. Examples: C 6 H 12 O 6 and CH 3 OH DO NOT DISSOCIATE BECAUSE THERE ARE NO IONS PRESENT. Mar 23 2:35 PM Arrhenius Definition of an Acid Arrhenius Acids a substance that yields hydronium ions, H 3 O + ions, as the only cation in solution. a) HCl + H 2 O Mar 23 1:31 PM 7

8 Arrhenius Definition of a Base Arrhenius Base a substance that yields hydroxide ions, OH ions as the only anion in solution NaOH Mg(OH) 2 Mar 23 1:50 PM A. Mg(OH) 2 + H 2 O Mg OH B. H 2 CO 3 + H 2 O H 3 O + + HCO 3 1) Which equation represents the dissociation of an Arrhenius acid? 2) Which equation represents the dissociation of an Arrhenius base? May 3 10:03 AM 8

9 Alternate Definition of an Acid Bronsted acid: A substance that donates a proton (H+) to another substance. "Proton DONOR". NH 3 + H 2 O NH OH Bronsted base: A substance that accepts a proton (H + ) from another substance. "Proton ACCEPTOR." Mar 24 10:23 AM Alternate Definition of a Base Bronsted base: A substance that accepts a proton (H + ) from another substance. Proton ACCEPTOR. NH 3 + H 2 O NH OH Mar 24 10:23 AM 9

10 Identify the Alternate (Bronsted) Acid and Base in each reaction: 1) H 2 CO 3 + H 2 O HCO 3 + H 3 O + 2) HSO 4 + H 2 O H 2 SO 4 + OH Mar 24 12:23 PM Practice Questions 1) Which species is classified as a Bronsted acid? A) CH 3 OH B) NaCl C) LiOH D) H 2 SO 4 2) Which of the following substances will turn red litmus paper blue? A) CH 3 OH B) NaCl C) LiOH D) H 2 SO 4 3) The compound NaOH can be described as an: A) arrhenius base and an electrolyte C) arrhenius acid and a nonelectrolyte B) arrhenius acid and an electrolyte D) arrhenius base and a nonelectrolyte 4) Which species donates H 3 O + ions as the only positive ion in solution? A) HCl B) Mg(OH) 2 C) CH 4 D) BaF 2 5) Given the reaction: NH 3 + HCl NH 4 Cl In this reaction, ammonia molecules (NH 3 ) act as a base because they A) donate hydroxide ions (OH ) C) accept hydrogen ions (H + ) B) accept hydroxide ions (OH ) D) donate hydrogen ions (H + ) Mar 24 12:23 PM 10