Warm-Up: To be turned in

Identify the type of reaction represented in the following equations:

C10H8 + 12O2 ---> 10CO2 + 4H2O8Fe + S8 ---> 8FeS

NaOH + HCl NaCl + H2O

Acid-Base and Redox Reactions

Acid-base Reactions

Arrhenius definition• Acid- increases H+ ion

concentration in an aqueous solution

• Base- increases OH- ion concentration in an aqueous solution

Brønsted-Lowery definition• Acid- proton donor• Base- proton acceptor• Conjugate acid- base that

has accepted a proton, becomes the acid in reverse reaction

• Conjugate base- acid that has donated a proton, becomes the base in the reverse reaction

Strong vs. Weak Acids/ Bases

• Strong acids/ bases completely ionize (form ions) aqueous solutions– Ex. Strong acids- all binary acids (except HF), H2SO4,

HNO3, HClO4

– Ex. strong bases- all hydroxides• Weak acids/bases do not ionize completely

aqueous solutions– Ex. Weak acids- HF, H3PO4, HCN, H2CO3

– Ex. Weak bases- NH3

Acid-base Reactions

• Acids and bases will combine in a double-replacement reaction to form water and a salt– HCl(aq) + NaOH(aq) H2O(l) + NaCl(aq)

• Some acids will decompose to form a non-metal oxide and water– H2CO3(aq) CO2(g) + H2O(l)

• Acids can also undergo single-replacement by metals to form hydrogen gas and a salt– Mg(s) + 2HCl(aq) → H2(g) + MgCl2(aq)

Redox reactions• Short for oxidation- reduction reactions• Reactions that show the movement of

electrons between substances– Oxidation Is Loss of electrons– Reduction Is Gain of electrons

Oxidation/reducing Agents

• Oxidation agent- substance which causes another to be oxidized– Reduced in the process

• Reducing agent- substance which causes another to be reduced– Oxidized in the process

Rules for determining oxidation states1. The oxidation number of any uncombined element is 0. 2. The oxidation number of a monatomic ion equals the

charge on the ion. 3. The more electronegative element in a binary

compound is assigned the number equal to the charge it would have if it were an ion.

4. The oxidation number of fluorine in a compound is always −1.

5. Oxygen has an oxidation number of −2 unless it is combined with F, when it is +2, or it is in a peroxide, such as H2O2, when it is −1.

Rules for determining oxidation states6. The oxidation state of hydrogen in compounds is

+1 unless it is combined with a metal, in which case it is −1.

7. In compounds, Group 1 and 2 elements and aluminum have oxidation numbers of +1, +2, and +3, respectively.

8. The sum of the oxidation numbers of all atoms in a neutral compound is 0.

9. The sum of the oxidation numbers of all atoms in a of polyatomic ion equals the charge of the ion.

Redox Example

F2(g) + 2NaCl(aq) → 2NaF(aq) + Cl2(g)

0 +1 -1 +1 -1 0reduced oxidized

Reducing agent

Oxidizing agent

Practice:Identify Oxidizing and Reducing Agents

2 Ag(s) + S(s) Ag2S(s)

2 Ag(s) + Cu2+(aq) 2 Ag+

(aq) + Cu(s)