1. CHAPTER 5 Review General, Organic, & Biological Chemistry Janice Gorzynski Smith

2. Concepts to Know 2 Smith. General Organic & Biolocial Chemistry 2nd Ed.  Define a chemical reaction  Correctly write a chemical reaction  Balance reactions by inspection  Calculate molecular mass for any compound or molecule  Apply mole ratios within molecules and between molecules.  Solve stoichiometry problems  Convert between mass and moles  Convert between % composition and mass  Identify limiting reagent  Calculate percent yield  Identify reduction and oxidation equations and pick out the compound being reduced or oxidized

3. Need to Memorize 3 Smith. General Organic & Biolocial Chemistry 2nd Ed. 6.02 x 10 23 is Avogadro’s number. Oxidation is the loss of electrons from an atom. Reducing agents are reduced Reduction is the gain of electrons by an atom. Oxidizing agents are reduced.

4. 4 Smith. General Organic & Biolocial Chemistry 2nd Ed. aA ( physical state ) + bB ( state )  cC ( state ) + dD ( state ) Writing and Balancing Equations HOW TO Balance a Chemical Equation Step [1] Write the equation with the correct formulas. The subscripts in a formula can never be changed to balance an equation, because changing a subscript changes the identity of a compound. Step [2] Balance the equation with coefficients one element at a time. Step [3] Check to make sure that the smallest set of whole numbers is used.

5. 5 aA + bB  cC + dD mass Amass Bmass Cmass D moles Amoles Bmoles Cmoles D a:b b:c c:d a:c a:d x ÷ MM Solve Stoichiometry Problems Limiting Reactant: Compare moles A & moles B after applying mole ratio. The reactant with the least number of moles AFTER mole ratio considered is the limiting reactant. Use limiting reactant # moles to determine moles of products that form

6. 6 Smith. General Organic & Biolocial Chemistry 2nd Ed. Zn + Cu 2+ Zn 2+ + Cu Zn loses 2 e – Cu 2+ gains 2 e − 6 Oxidation half reaction:ZnZn 2+ + 2 e − Each of these processes can be written as an individual half reaction: loss of e − Reduction half reaction:Cu 2+ + 2e − Cu gain of e − Redox Half Reactions