A. Measuring Matter 1. Statement Chemistry is a quantitative science. 2. What is one way to measure matter? One way to measure matter is to count how many of something you have. 3. Statement Knowing how the count, mass, and volume of an item relate to a common unit allows you to convert among these units. This is called Dimensional Analysis. Sample Problem 10.1 What is the mass of 90 average-size apples if 1 dozen of the apples has a mass of 2.0 Kg? (15 Kg) Do the problems 1 and 2 at the bottom of page 307. B. What is a Mole? 1. How do chemists count the number of atoms, molecules, or formula units in a substance? The chemists use a unit that is a specified number of particles. The unit is called the mole. 2. What is a mole? It represents 6.02 x particles of that substance. It is the SI unit for measuring the amount of a substance. B. What is a Mole? 3. What is the name of number of representative particles in a mole? It is called Avogadros number. It was named in honor of the Italian scientist Amedeo Avogadro di Quaregna, who helped clarify the difference between atoms and molecules. 4. What does the term representative particle mean? It refers to the species present in a substance, usually atoms, molecules, or formula units. B. What is a Mole? 5. Statement The mole allows chemists to count the number of representative particles in a substance. 6. Converting between Number of Particles and Moles 1 mole = 6.02 x particles Sample Problem 10.2 Converting Number of Atoms to Moles Magnesium is a light metal used in the manufacture of aircraft, automobile wheels, and tools. How many moles of magnesium is 1.25 x atoms of magnesium? Do Problems 3 and 4 at the bottom of Page 309. Sample Problem 10.3 Converting Moles to Number of Atoms Propane is a gas used for cooking and heating. How many atoms are in 2.12 moles of propane (C 3 H 8 )? Do problems 5 and 6 at the bottom of page 311. C. Molar Mass 1. What is Molar Mass? It is the mass of a mole of a substance. 2. How do you determine the molar mass of an element and of a compound? The atomic mass of an element expressed in grams on the Periodic table. To Calculate the molar mass of a compound, do the following chart: SymbolSubscriptAtomic MassTotal Mass Sample Problem 10.4 Finding the Molar Mass of a Compound The decomposition of hydrogen peroxide (H 2 O 2 ) provides sufficient energy to launch a rocket. What is the molar mass of hydrogen peroxide? Do problems 7 and 8 at the bottom of page 315. 10.1 Lesson Check Do the following problems: 12, 13, 14, 15 A. The Mole-Mass Relationships 1. How do you convert the mass of a substance to the number of moles of the substance? Use the molar mass of an element or compound to convert between the mass of a substance and the moles of the substance. Sample Problem 10.5 Converting Moles to mass Items made out of aluminum are resistant to corrosion because of the aluminum reacts with oxygen in the air to form a coating of aluminum oxide (AL 2 O 3 ). This tough, resistant coating prevents any further corrosion. What is the mass, in grams, of 9.45 mole of aluminum oxide? Do Problems 16 and 17 at the bottom of page 318. Sample Problem 10.6 Converting Mass to Moles When iron is exposed to air, it corrodes to form red-brown rust. Rust is iron (III) oxide (Fe 2 O 3 ). How many moles of iron (III) oxide are contained in 92.2 grams of pure Fe 2 O 3 ? Do problems 18 and 19 at the bottom of page 319. B. The Mole-Volume Relationship 1. What is Avogadros Hypothesis? It states that equal volumes of gases at the same temperature and pressure contain equal numbers of particles. 2. What is STP? It is standard temperature and pressure. The temperature is 0C. Pressure is kPa or 1 atmosphere (atm). 3. What is molar volume? 22.4 L Sample Problem 10.7 Calculating Gas Quantities at STP Sulfur dioxide (SO 2 ) is a gas produced by burning coal. It is an air pollutant and one of the causes of acid rain. Determine the volume, in liters, of 0.60 mole SO 2 at STP. Do problems 20 and 21 at the bottom of page 321. Sample problem 10.8 Calculating the Molar Mass of a Gas at STP The density of a gaseous compound containing carbon and oxygen is found to be g/L at STP. What is the molar mass of the compound? Do problems 22 and 23 at the bottom of page 322. 10.2 lesson Check Do the following problems: 26, 27, 28, 29, 30, and 31. A. % Composition of a CMPD 1. What is percent composition? It is the relative amounts of the elements in a compound. 2. How do you calculate the percent composition of a compound? The percent by mass of an element in a compound is the number of grams of the element divided by the mass in grams of the compound, multiplied by 100%. Sample Problem 10.9 Calculating Percent Composition from Mass Data When a g sample of a compound containing only magnesium and oxygen is decomposed, 5.40 grams of oxygen is obtained. What is the percent composition of this compound? Do problems 33 and 34 at the bottom of page 326. Sample Problem Calculating Percent Composition from a Formula Propane (C 3 H 8 ), the fuel commonly used in gas grills, is one of the compounds obtained from petroleum. Calculate the percent composition of propane. Do problems 35 and 36 at the bottom of page 327. Sample Problem Calculating the Mass of an Element in a Compound Using Percent Composition. Calculate the mass of carbon and the mass of hydrogen in 82.0 grams of propane (C 3 H 8 ). Do problems 37 and 38 at the bottom of page 329. B. Empirical Formulas 1. What is the empirical formula of a compound? It gives the lowest whole-number ratio of the atoms or moles of the elements in a compound. 2. How can you calculate the empirical formula of a compound? Sample Problem Determining the Empirical Formula of a Compound A compound is analyzed and found to contain 25.9% nitrogen and 74.1% oxygen. What is the empirical formula of the compound? Do problems 39 and 40 at the bottom of page 331. C. Molecular Formulas 1. What is the molecular formula of a compound? It is a simple whole-number multiple of its empirical formula. It can be same as its experimentally determined empirical formula. Sample problem Finding the Molecular Formula of a Compound Calculate the molecular formula of a compound whose molar mass is 60.0 g/mole and empirical formula is CH 4 N. Do problems 41 and 42 at the bottom of page 333. 10.3 Lesson Check Do the following problems: 46, 47, and 48. Study Guide on Page 336 Math Tune-Up: Mole Problems on Page 337 Lesson by Lesson on pages Test on Chapter 10 Chemical Quantities