Unit 5 Notepack: Chapters 10 Chemical Quantities NAME Unit 5 Chemical Names, and Formulas & Moles Unit Goals- As you work through this unit, you should be able to: 1. Distinguish between ionic and molecular compounds. 2. Relate cations and anions to metals and nonmetals. READ: Period: 3. Distinguish between chemical formulas, molecular formulas, and formula units. Chapter 9 & 10 4. Know the charges of the formulas for monatomic ions using the periodic table. 5. Be familiar with the charges and the formulas for polyatomic ions. 6. Apply the rules for naming and writing formulas for binary and ternary ionic compounds. 7. Apply the rules for naming and writing formulas for binary molecular compounds. 8. Describe how Avogadro s number is related to a mole of any substance and the number of different particles that are a part of the substance. 9. Calculate the mass of a mole of any substance. 10. Calculate the volume of a mole of any gaseous substance at STP. 11. Use moles to convert among measurements of mass, number of particles, and volume. 12. Calculate the percent composition of a substance from its chemical formula or experimental data. 13. Derive the empirical formula and molecular formula of a compound from experimental data. Assignments: Activities, Labs & Test Description 5 4 0 Mole Activity A5 A6 A7 A1 A2 A3 A4 Chemical Names and Formulas WS (Goals 1-3) Ionic Compounds WS (Goals 4-6) Molecular Compounds WS (Goal 7) Mole Conversions WS (Goals 8-9) More Mole Conversions WS (Goals 9-11) Percent Composition WS (Goal 12) Emperical and Molecular Formulas WS (Goal 13) Mole Chalk Activity Hydrated Crystals Percent Composition Lab Emperical Formula Lab Unit 5 Test & Naming Master Test Late Lab Stamp (this stamp means you are not qualified to do lab and test corrections) Key Terms: mole, Avogadro s number, molar mass, molar volume, STP, percent composition, molecular formula, empirical formula, Demo s: Ethanol Spark Plug, Glass samples of moles, 1 mole of CO 2 in balloon, Making Water
Chapter 10.1: Mole What is a mole? How do we measure quantities of matter? What are examples of counting units? What can we count in chemistry? How much is a mole? What is molar mass? What are the four representative particles that we can calculate the molar masses of? Give examples. 10.1 Sample Calculations: We must show our work using dimensional analysis. 1. How many moles of magnesium is 1.25 x 10 23 atoms of magnesium? 2. How many moles is 2.80 x 10 24 atoms of silicon?
3. How many molecules is 0.360 mole of water? 4. How many moles are equal to 2.41 x 10 24 formula units of sodium chloride (NaCl)? 5. How many atoms are in 2.12 moles of propane (C 3 H 8 )? 6. How many atoms are there in 1.14 mole of sulfur trioxide? 7. How many moles are there in 4.65 x 10 24 molecules of nitrogen dioxide? 8. How many atoms of Carbon are in 2.0 moles of C 12 H 22 O 11, sucrose sugar? 9. What is the molar mass of carbon? 10. What is the molar mass of hydrogen gas? 11. What is the molar mass of sulfur? 12. What is the molar mass of sulfur trioxide? 13. What is the molar mass of hydrogen? 14. What is the molar mass of carbon dioxide? 15. What is the molar mass of sodium chloride?
16. What is the molar mass of ammonium carbonate? 17. What is the molar mass of potassium oxide? Review Problems: 1. Find the gram formula mass of each compound: a. lithium sulfide b. iron (III) chloride c. calcium hydroxide 2. How many oxygen atoms are in a representative particle of each substance? a. ammonium nitrate b. acetylsalicylic acid (C 9 H 8 O 4 ), the chemical name of aspirin c. ozone (O 3 ), a disinfectant and natural molecule found in the atmosphere 3. How many moles in each of the following: a. 1.50 x 10 23 molecules of ammonia, NH 3? b. 1 billion (1 x 10 9 ) molecules of oxygen, O 2?
c. 4.81 x 10 24 atoms of lithium, Li? Chapter 10.2: Mole mass and Mole Volume Relationships. How are moles and mass related? What is STP? Why is STP important when quantifying gases? What is the volume of a Mole of Gas at STP?
Mole Map One step examples: 1. Find the mass of 2.7 moles of C 6 H 12 O 6. 2. How many moles are in 6.72g of Silver Nitrate? 3. Determine the volume, in liters, of 0.60 moles of sulfur dioxide gas at STP. 4. Determine the number of moles of oxygen gas in 11.5 L at STP. Multi-step examples: 5. What is the mass of 27 liters of nitrogen dioxide at STP?
6. If you have 9.64 x 10 24 mlc s of carbon dioxide, what would be the volume of that gas at STP? 7. If you weight 301 grams of Aluminum Oxide, how many formula units will you have? Sample Calculations: 1. Find the mass, in grams of each. a. 3.32 mole of potassium atoms, K. b. 4.52 x 10 21 molecules of C 6 H 12 O 6 c. 0.0112 liters of carbon dioxide 2. Calculate the number of moles in 75 grams of each substance. a. dinitrogen trioxide b. sodium oxide 3. How many grams are in 9.45 liters of dinitrogen trioxide? 4. Find the number of moles in 92.2 grams of iron (III) oxide
5. What is the volume at STP of these gases? a. 3.20 x 10-3 mol carbon dioxide b. 0.960 grams of methane, CH 4 c. 3.70 x 10 24 molecules nitrogen gas 6. Assuming STP, how many moles are in these volumes? a. 67.2 liters of sulfur dioxide gas b. 0.880 liters of helium gas c. 1,000 liters of neon gas Chapter 10.3: Percent Composition and chemical formulas What is percent composition of a compound? How do we find the percent of anything?
What is percent composition used for and how do we show our work? How do you calculate the percent composition of a compound? Example: Calculate the percent composition of potassium dichromate. Sample Calculations: 1. 9.30 grams of magnesium combine completely with 3.48 grams of nitrogen gas to form a compound. What is the percent composition of this compound? 2. 29.0 grams of silver combine completely with 4.30 grams of sulfur to form a compound. What is the percent composition of this compound? 3. Calculate the percent composition of these compounds: a. sodium bicarbonate b. ammonium chloride c. sulfur trioxide
A. Using Percent as a Conversion Factor 1. You can use percent composition to calculate the number of of an element contained in a amount of a compound. To do this, you multiply the mass of the compound by a conversion factor that is based on the percent composition. Example: Calculate the mass of carbon in 82 grams of propane (C 3 H 8 ). Sample Calculations: Calculate the grams of nitrogen in 125 grams of each fertilizer. a. CO(NH 2 ) 2 b. NH 3 c. NH 4 NO 3 B. Calculating Empirical Formulas 1. Determining the percent composition of a compound has an important application calculating the empirical formula: 2. Define empirical formula: 3. Define molecular formula: 4. The empirical formula may or may not be the same as the molecular formula 5. Practice: These are all molecular formulas, in other words, true formulas. Write their empirical formulas: H 2 0 H 2 O 2 CO 2 N 2 O 4 6. We can use the percent composition of a compound to determine its empirical formula. Example: What is the empirical formula of a compound that is 25.9% nitrogen and 74.1% oxygen?
Sample Calculations: 1. Calculate the empirical formula of each compound. a. 94.1% O, 5.9% H b. 79.8% C, 20.2% H c. 67.6% Hg, 10.8% S, 21.6% O d. 27.59% C, 1.15% H, 16.09% N, 55.17% O C. Molecular Formula Calculations 1. The molecular formula is either the as the empirical formula or it is a simple number multiple of an empirical formula. For example, the empirical formula of glucose is. The molecular formula is six times larger equaling. Notice that the molar mass of the molecule is times larger than the empirical formula 2. Calculate the molecular formula of a compound whose molar mass is 60.0 g/mol and the empirical formula is CH 4 N. 3. Find the molecular formula of ethylene glycol, which is used as antifreeze. The molar mass is 62 g/mol and the empirical formula is CH 3 O