Unit 4 Acids and Bases Lesson 1 Acid and Base Properties And Definitions

Properties of Bases Neutralize acids Are electrolytes that conduct electricity Change litmus paper blue Feel slippery Taste bitter (baking soda) Ex: NaOH, Ca(OH)2, KOH, Zn(OH)2 -- notice they all contain OH.

Properties of Acids Ex: HCl, HNO3, H2SO4 –notice they all contain H. Neutralize bases Are electrolytes that conduct electricity Change litmus paper red Taste sour (vinegar, lemon juice) React with metals such as Mg and Zn to make H2 Mg(s)+ 2 HCl (aq)  MgCl2 (aq) + H2(g). Ex: HCl, HNO3, H2SO4 –notice they all contain H.

Notice, a salt does not contain H, or OH. Salts A salt is the neutralization product when an acid and a base react to produce water. HCl + NaOH  NaCl + H2O Notice, a salt does not contain H, or OH.

The Arrhenius Theory of Acids and Bases

produces H+ in solution Arrhenius acid produces H+ in solution HCl ® H+ + Cl- H+ is called a proton Arrhenius base produces OH- in solution NaOH ® Na+ + OH-

Bronsted-Lowry Theory of Acids and Bases

Bronsted-Lowry Theory of Acids and Bases -more general theory -to accommodate reactions at equilibrium. -acids as proton donors -bases as proton acceptors

Bronsted Acid Chemistry 12 A proton donor H+ HCl + H2O ® H3O+ + Cl- strong Bronsted Base Chemistry 12 A proton acceptor NH3 + H2O ⇄ NH4+ + OH- H+ weak

Write a Bronsted reaction for the base HCO3- weak H+ H+ HCO3- + H2O ⇄ H2CO3 + OH- base acid acid base HCO3- and H2CO3 H2O and OH- These are called “Conjugate acid-base pairs” They differ by one proton H+

In Summary 1. Arrhenius bases dissociate in water to produce OH- 2. Bronsted bases accept a proton from water to produce OH- 3. Arrhenius acids dissociate in water to form H+ 4. Bronsted acids donate a proton to water to form H3O+ 5. H+ is the same as H3O+

+ H+ is another way to show H3O+. H+ + H2O ⇋ H3O+ Hydronium ion Proton

Conjugate acids and bases

Conjugates A conjugate acid-base pair (conjugate pair) is a pair of chemical species which differ by only one proton (H+) NH4+, NH3 A conjugate acid is the member of conjugate pair that HAS the extra proton. NH4+ A conjugate base is the member of the conjugate pair that LACKS the extra proton. NH3

Conjugate Acid Conjugate Base One more H+ 1 less H+ C6H5OH C6H5O- H2CO3 H+ gives a +1 Charge. HCO3- H2O OH- HPO42- PO43- H2PO4- HPO42- C6H5COOH C6H5COO- NH4+ NH3 Fe(H2O)63+ Fe(H2O)5(OH)2+

Acids and Bases Chart 231 Relative Strengths of Bronsted-Lowry Acids and Bases Aqueous solutions at room temperature.

Strong Acids Weak Acids

Strong Acids Left side of Acid Chart -top six- Completely ionize in water Are good conductors. Produce large amounts of H3O+. Have very large Ka’s, that is why you do not find them on the chart. Use a “®” and not “⇄” because it is not an equilibrium situation. HCl + H2O ® H3O+ + Cl-

Weak Acids Left side of the Acid Chart below the top six.   Left side of the Acid Chart below the top six. Do not completely ionize in water. Are poor conductors. Produce small amounts of H3O+. Have small Ka’s, you will find Ka values on the chart. Use a “⇄” and not “®” It means they are Equilibrium situations! HF + H2O ⇄ H3O+ + F- Ka = [H3O+][F-] = 3.5 x 10-4 from page 334 [HF] Water is not included because it is a pure liquid! Its concentration is constant!

We use H+ and H3O+ interchangeably. They mean the same thing! You can also write:  HF + H2O ⇄ H3O+ + F- HF + H2O ⇌ H+ + F-   [H+][F-] Ka = = 3.5 x 10-4 [HF] We use H+ and H3O+ interchangeably. They mean the same thing!

Balance these neutralization equations H2SO4 + NaOH HCl + Sn(OH)4