1. Chemistry Classes Review for Unit Exam Friday June 7, 2013

2. Format Approximately 20 questions Multiple Choice Scantron (bring #2 pencils) You may use an index card of information as a reference

3. Topics Types of reactions Balancing Equations Conversions and conversion factors Stoichiometry Percent Yield

4. Definitions Know the following: – Reactants and Products – Law of Conservation of Matter – Molar Mass – Stoichiometry – Balanced Equations – Types of Reactions (for Mr. Basa’s classes)

5. Types of reactions Synthesis: Decomposition: Single Replacement: Double Replacement: Combustion:

6. Conversions (practice problems) 1. How many atoms are there in a mole of helium? 2. How many molecules are there in a mole of methane? 3. What is the mass of 1 mole of magnesium? 4. What is the mass of 2 moles of carbon dioxide? 5. How many atoms are there in 27.9 grams of iron?

7. Balancing equations Remember: – Count # of atoms for reactants and # of atoms for products (i.e., on both sides of the arrow) – If not equal, place a number on the coefficient line (nowhere else!) to multiply times the # of atoms for that compound, and recount – If still not equal, change the coefficient and repeat the above

8. Practice problems

9. Stoichiometry The goal is to have use the number of moles of each compound in a reaction to answer questions about that reaction. Write down the given information Understand what the question is asking for Make a “model” to solve the question (continued)

10. Stoich, cont. Example of model: gram  mole  mole  gram The 1 st pair of parentheses (what needs to be converted) will always be the given The 3 rd pair of parentheses will usually be the molar ratio The last pair of parenthesis will be what you are trying to solve for

11. Practice problems

12. Percent Yield Easier than you think! : ) Determine what the theoretical yield is (might use stoich to solve) Record your actual yield Percent Yield = actual yield X 100 theoretical yield

13. Practical hints Work quickly (i.e., use time wisely: know when it’s the half way point of the class, etc.) Answer questions you know right away and come back to the more challenging questions For your choices, eliminate distractor choices Study hard each night before the test – divide the topics so you don’t “cram” all at once Good luck!