Aim How can we write redox half reactions

Aim: How can we write redox half reactions? Aim: 1. Take out a calculator and reference tables. 2. Regarding the following reaction: 2 Al + 3 Cu 2+ 2 Al 3+ + 3 Cu • Is this a redox reaction? • Which part of the reaction is oxidized? • Which part of the reaction is reduced? • Which is the oxidizing agent? Which is the reducing agent?

Answer to the do now

How can we show the oxidation and reduction reactions in chemical formulas? • A half-reaction shows either the oxidation or reduction portion of a redox reaction. • A reduction half reaction will show an atom or ion gaining one or more electrons. • Example: Fe 3+(aq) +3 e- Fe(s) • An oxidation half reaction will show an atom or ion losing one or more electrons. • Example: Fe(s) Fe 3+(aq) + 3 e-

Rules for writing half reactions 1. First, assign an oxidation number to each element. Example: Cu + Ag. NO 3 Cu(NO 3)2 +Ag 2. Write the half reactions to show the change in oxidation state. 3. Write in the electrons that were exchanged to show the oxidation number changed.

Examples: Write half reactions for the following equations: Mg + Cl 2 Mg. Cl 2 + H 20 HCl. O +HCl

Activity/Homework • Activity – Answer the practice regents questions on the paper you were given. • Homework - Review Book Pages 162 -165 • Copy and answer # 11 -14, 19 -21, 24 -27, 32 -36