Chapter 1 Fundamental Concepts of Chemistry 1.1 Atoms, Molecules, and Compounds 1.2 Measurements in Chemistry 1.3 Chemical Problem Solving 1.4 Counting Atoms: The Mole 1.5 Amounts of Compounds 1.6 Aqueous Solutions 1.7 Writing Chemical Equations 1.8 The Stoichiometry of Chemical Reactions 1.9 Yields of Chemical Reactions 1.10 The Limiting Reagent Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.1 Atoms, Molecules and Compounds Learning Objectives: recognize elemental symbols and names of the elements name compounds from molecular pictures Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.1 Atoms, Molecules and Compounds What is matter made of? Democritus had the answer: All matter was made of very small particles – much too small to see and he called the small particles atoms. From the Greek word atomos meaning “uncuttable” Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Macro vs. Micro Macroscopic – able to be seen by the human eye. Microscopic – requires the use of a magnifying device Allows us to see the underlying structure of a chemical substance Can we go any smaller? Atomic View – reveals the building blocks of matter Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Classifications of Matter Matter can be divided into two main classes 1. Atoms (and elements) 2. Molecules Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. How Small are Atoms? A sample of carbon the size of a period at the end of a printed sentence contains more atoms than the number of stars in the Milky Way. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Atomic Colour Coding Fig 1-4 Pg 7 Color-coded scale models of 10 types of atoms that appear frequently in this book. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Elements A substance that contains only one type of atom is called a chemical element. Each has A unique name A unique number (Z) Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Molecules A molecule is a combination of two or more atoms held together in a specific shape by attractive forces. The simplest is a molecule containing two of the same atoms. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Chemical Formulas Compound – a substance that contains more than one element. For example, water is composed of hydrogen and oxygen The chemical formula describes the atomic composition of the elements. Water’s chemical formula is H2O – 2 hydrogen atoms and 1 oxygen atom Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Some Simple Molecules Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Exercises What are the chemical formulas of the following compounds? 1.1.1 What are the elemental symbols for cerium, cesium, copper, calcium and carbon? 1.1.2 What are the names of the elements represented by the symbols Zr, Ni, Sn, W, Se, Be and Au? 1.1.3 Molecular pictures of some molecules are shown here. What are their chemical formulas? 1 2 3 Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 4 5 1.2 Measurements in Chemistry Learning Objectives: recognize the SI units commonly used in chemistry, and perform some common unit conversions Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.2 Measurements in Chemistry Size – defined by length, area and volume Mass (m) – the certain quantity of matter Time (t) – to determine how long it takes for a chemical transformation to take place Temperature (T) – determines the direction of heat flow Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Frequently Used Symbols for Magnitudes Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Units Système International (SI) expresses each fundamental physical quantity in decimally related units Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Unit Conversions We frequently need to convert a measurement from one unit to another. When multiplying numbers we also multiply units and when dividing numbers we also divide units Never forget the units! Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Temperature Two scales are commonly used: 1. Centigrade or Celsius (°C) The boiling point of water is set at 100 °C and the freezing point at 0 °C. 2. Kelvin (K) (also called Absolute scale) Has the same divisions as the Celsius scale, but a different zero point -273.15 °C = 0 K 0 K is referred to as absolute zero…WHY? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Temperature T(K) = T(°C) + 273.15 T (°C) = T (K) - 273.15 Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Precision and Accuracy The patterns of bullets striking a target illustrate the notions of precision and accuracy. (a) A precise and accurate pattern (b) A precise but inaccurate pattern (c) An imprecise and inaccurate pattern (d) An imprecise pattern with one accurate shot Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Significant Figures The number of digits expressed in a numerical value is called the number of significant figures. How to determine “sig figs” Read the number from left to right and count all the digits starting with the first non-zero digit Place a decimal point after the value when its trailing zeros are significant 110 has 2 sig figs 110. has 3 sig figs Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Precision in Calculations 1. 2. 3. When adding or subtracting, the number of decimal places in the result is the number of decimal places in the number with the fewest places. When multiplying or dividing, the number of significant figures in the result is the same as in the quantity with the fewest significant figures. Postpone adjusting result to the correct number of significant figures until a calculation is complete Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Section Exercises What are the chemical formulas of the following compounds? 1.2.1 Convert the following measurements to scientific notation and express in base SI units: 0.000 463 L, 17 935 km, and 260 000 h (precise to three significant figures). 1.2.2 One light-year is the distance light travels in exactly one year. The speed of light is 1.08 x 109 km/h. Express the speed of light and the length of one light-year in SI units. 1.2.3 Convert each of these measurements to SI units: 155 pounds (mass of a typical person, 1 kg = 2.2 pounds), 110.0 yards (full length of a Canadian football field, 1 yard = 91.44 cm), 39 °C (body temperature of someone with a slight fever), and 365.2422 days (length of one year). Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.3 Chemical Problem Solving Learning Objective: Analyze and solve problems in a consistent, organized fashion Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.3 Chemical Problem Solving Step 1 Determine what is asked for. What type of problem is it? What are you asked to find? Step 2 Visualize the problem. Draw pictures that illustrate what takes place. If chemical changes occur, draw molecular pictures. Step 3 Organize the data. What data are available? How are the data related to what is asked for? Step 4 Identify a process to solve the problem. What concepts are required? What equations apply? Step 5 Manipulate the equations. If necessary, do calculations in steps. Solve for what is asked for. Step 6 Substitute and calculate. Keep track of units. Use the correct number of significant figures. Step 7 Does the result make sense? Are the units consistent? Is the result sensible? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1 - 1 Electroplating is a process by which a metal such as copper is coated with another metal such as silver or chromium. The transfer of metal atoms is driven by an electrical current. In an electroplating process, a spoon is coated with silver from a silver rod. In the process, 1.0 x 1021 atoms are transferred from the rod to the spoon, and the rod loses 0.179 g of its mass. Use this information and the density of silver (10.50 g/cm3) to estimate the volume occupied by one silver atom. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.4 Counting Atoms: The Mole Learning Objective: Solve mass-number-molecular weight type problems Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.4 Counting Atoms: The Mole Mole – the amount of substance that contains as many elementary entities (atoms, molecules, or other particles) as there are atoms in exactly 12 g of 12C 1 mol = 12 g of 12C But how many atoms are there in 12 g of 12C? Using a mass spectrometer, it was determined that 1 atom of 12C = 1.992646 x 10-23 g So, let’s do the math… Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. The Mole (aka Avogadro’s Number) 1 mole 6.022 10 23 Avogadro’s number is a conversion unit: 1 mole = 6.022 x 1023 “items” “items” = atoms, molecules, atoms, etc… The symbol is NA = 6.022 x 1023 “items”/mol Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Moles and Isotopic Mass Most elements are found on the earth as a mixture of isotopes in a constant ratio. A single atom of each isotope has a unique mass. However, is it useful to discuss a single atom? So instead, we think of a mole of atoms. How much does a mole of atoms of an isotope weigh? Let’s look at 13C. Its atomic mass is 2.15 x 10-23 g; what is the mass of one mole of 13C? Is this the mass for carbon on the periodic table? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Molar Mass We must take into account all the isotopes of each element and their percent abundance. (What is this?) Molar mass of an element is a weighed average of the masses of all the isotopes of one element. Once calculated, it is the mass of one mole of atoms of the elements. Elemental molar mass = (Fractional abundance)(Isotopic molar mass) Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Mass-Mole-Atom Conversions Molar mass can be thought of as a conversion factor. m n M For instance M (Ag) = 107.86 g/mol 107.86 g Ag = 1 mol of Ag If a bracelet contains 168 g of Ag, how many moles of silver is this? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. The flowchart shows the conversion processes among the number of moles, the mass, and the number of atoms for a sample of an element. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.5 Amounts of Compounds Learning Objective: Perform mole-mass-number conversions Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.5 Amounts of Compounds The molar mass of compound is found by adding together the molar masses of all of its elements, taking into account the number of moles of each element present. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1-3 Converting Line Structures Construct the formulas and determine the chemical formulas from the following line drawings: Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1-4 Molar Mass of a Molecule The line drawing and chemical formula of Sevin, a common insecticide, appears below. Determine the molar mass of Sevin. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1-5 Metal salts often exist as hydrates. One example is iron(II) nitrate hexahydrate. Determine the molar mass of this compound. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Mass-Mole-Number Conversions for Compounds Just as one can convert between grams and moles using atomic molar mass, one can convert using the molar mass of compounds Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1 - 6 Ammonium nitrate (NH4NO3) is used as a fertilizer because it is a good source of nitrogen atoms. It is such a good source, in fact, that it ranks among the top 15 industrial chemicals produced yearly in the world. How many moles of nitrogen atoms are present in a 454 g bag of NH4NO3 fertilizer? How many atoms is this? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.6 Aqueous Solutions Learning Objective: Calculate concentrations of solutions and diluted solutions Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.6 Aqueous Solutions Solution – a homogeneous mixture of two or more substances, in which one is called the solvent and the other is the solute Solvent – main medium, what is there in the largest quantity Solute – dissolved in the solvent Sugar and Water Sugar (solute) and Water (solvent) NaCl and Water NaCl (solute) and Water (solvent) Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Concentration Concentration – the amount of a solute dissolved in a given quantity of solvent A concentrated solution has a large amount of solute in it. A dilute solution has a small amount of solute in it. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Molarity The concentration unit which is most useful is molarity. Molarity – the number of moles of solute dissolved in 1 L of solution quantity of A (mol) n Molarity of A (c) Volume of Solution (L) V Just like molar mass, molarity can be used as a conversion unit. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1 - 7 What mass of nickel(II) chloride hexahydrate is required to prepare 250. mL of aqueous solution with a concentration of 0.255M? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Species in Solution What chemical species are in an aqueous solution? Water will always be present in excess. There will also be solute species that are either molecules or ions. When ionic compounds dissolve in water, they dissociate into their ions. Remember: polyatomic ions remain intact when a salt dissolves in water. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1 - 8 Find the molarities of the ionic species present in 250. mL of an aqueous solution containing 1.75 g of ammonium sulfate (NH4)2SO4. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Dilutions What if you have a concentrated solution and you would like to dilute it to another concentration? Concentrationi × Volume i = Concentration f × Volume f ci Vi =c f Vf Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1 – 9 Dilution of a Solution Aqueous hydrochloric acid, HCl, is usually sold as a 12.0 M solution, commonly referred to as concentrated HCl. A chemist needs to prepare 2.00 L of 1.50 M HCl for a number of different applications. What volume of concentrated HCl solution should the chemist use in the dilution? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1 – 10 Preparing Solutions An agricultural chemist wished to study the effect of varying fertilizer applications on the growth of tomato plants. The chemist prepared a stock aqueous solution of urea, (NH4)2CO, by dissolving 1.75 g of this compound in water to make 1.00 L of solution. Then, she prepared a series of more dilute solutions to apply to her tomato plants. One of these solutions contained 5.00 mL of stock solution diluted to give a final volume of 25.00 mL. What was the concentration of urea in this diluted solution? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.7 Writing Chemical Equations Learning Objective: Balance chemical reactions Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.7 Writing Chemical Equations Molecular nitrogen reacts with molecular hydrogen to yield ammonia. Molecular nitrogen + molecular hydrogen → ammonia N2 + H2 → NH3 Is this a correct representation of what happens? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Using the molecular formulas, we are able to express what occurs in the chemical reaction N2 + H2 → NH3 We do have one problem; it does not give amounts correctly (it is not balanced). In chemical reactions, atoms cannot be created or destroyed. N2 + 3 H2 → 2 NH3 Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Stoichiometry… The relationship between quantities in chemical reactants and products in a balanced chemical equation. The coefficients in a balanced equation are called the stoichiometric coefficients. The reactants are consumed in a reaction, while the products are produced. Identify the reactants, products and stoichiometric coefficients below. 2 Mg + O 2 2 MgO Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Balancing Equations To balance, we place counting numbers in front of the formulas until the equation is balanced. 2. The numbers are called stoichiometric coefficients and they represent numbers of atoms, molecules or moles of reactants and products. 3. In a balanced equation, there must be the same number of atoms of each element on both sides. 4. And, the charge must be conserved (What does this mean?) 1. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1 - 11 Ammonium nitrate (NH4NO3) explodes when it is heated above 300 °C. The products are three gases: molecular nitrogen, molecular oxygen and steam (water vapor). Write a balanced equation for the explosion of ammonium nitrate. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Balancing Combustion Equations C 5H12 + O2 CO 2 + H2 O Combustion equations involve hydrocarbons burning in oxygen to form carbon dioxide and water • Step 1: Balance the carbon atoms • Step 2: Balance the hydrogen atoms • Step 3: Balance the oxygen atoms Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.8 Stoichiometry of Chemical Reactions Learning Objective: Calculate the amount of a product from the amounts of the reactants and a balanced chemical reaction Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.8 Stoichiometry of Chemical Reactions Once an equation is balanced, you can use it to relate reactants and products. The key is the stoichiometric coefficients! Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Making a Pancake 1 1 1 egg + cup milk + cup flour + 1 tbsp sugar 1 pancake 2 2 If I have 2 eggs and an unlimited supply of the rest of the ingredients how many pancakes can I make? From practical knowledge, you would say 2 pancakes. In chemistry, stoichiometric calculations are based on the mole. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. N2 + 3 H2 → 2 NH3 How many grams of hydrogen are need to produce 68 g of ammonia? Step 1: Write what you know Step 2: Ask yourself, how can I relate this to what I need? Once your problem is in units of moles, you should think to yourself, “I should be using the balanced equation!” Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. N2 + 3 H2 → 2 NH3 First you must convert grams to moles 1 mol NH3 68 g NH3 × 17.0 g NH3 Once you have moles, you can use the balanced equation 1 mol NH3 3 mol H2 68 g NH3 × × 17.0 g NH3 2 mol NH3 Finally, convert moles back to grams 1 mol NH3 3 mol H2 2.02 g H2 68 g NH3 × × × = 12 g H2 17.0 g NH3 2 mol NH3 molH2 Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1 - 12 Geranyl formate is used as a synthetic rose essence in cosmetics. The compound is prepared from formic acid and geraniol: HCO2H + C10H18O → C11H18O2 + H2O A perfumery needs some geranyl formate for a batch of perfume. How many grams of geranyl formate can a chemistry make from 375 g of geraniol? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1 - 13 Poisonous hydrogen cyanide (HCN) is an important industrial chemical. It is produced from methane (CH4), ammonia, and molecular oxygen. The reaction also produces water. An industrial manufacturer wants to convert 175 kg of methane into HCN. How much molecular oxygen will be required for this synthesis? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Reality Check… When you mix pancakes, do you always make the amount that the box says with the correct ingredients? Or, when baking cookies…it says you can make 3 dozen, can you really? The same follows for chemical reactions. Almost always, chemical reactions produce smaller amounts of products than predicted by stoichiometric analysis. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. WHY? 1. 2. 3. Many reactions stop before reaching completion. Competing reactions often consume starting materials. When the product of a reaction is purified and isolated, some of it is inevitably lost during the collection process. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.9 Yields of Chemical Reactions Learning Objective: Calculate reaction yields Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.9 Yields of Chemical Reactions Theoretical amount – the maximum quantity of a product that can be obtained from a chemical reaction (in a perfect world) Actual amount – the quantity of a product that is actually obtained from a chemical reaction in the laboratory actual amount Percent Yield 100 theoretical amount Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1 - 14 According to Example 1-12, it is possible to make 443 g of geranyl formate from 375 g of geraniol. A chemist making geranyl formate for the preparation of a perfume uses 375 g of starting material and collects 417 g of purified product. What is the percent yield of this synthesis? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1 - 15 The industrial production of hydrogen cyanide is described in Example 1-13. If the yield of this synthesis is 97.5%, how many kilograms of methane should be used to produce 1.50 x 105 kg of HCN? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.10 The Limiting Reactant Learning Objective: Solve limiting-reagent-type problems Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. 1.10 The Limiting Reactant 1 1 1 egg + cup milk + cup flour + 1 tbsp sugar 1 pancake 2 2 Let’s return to the pancake example. If I have 12 eggs, 4 L of milk, 1 cup of flour and 1 kg of sugar, what is my limiting reactant? Limiting reactant – determines or limits the amount of product formed. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. If we start with six molecules of H2 and four molecules of N2, the six molecules of H2 will combine with two molecules of N2 to make four molecules of NH3 Two molecules of N2 will be left over. The H2 is the limiting reactant Once again, it is best to work in units of moles. Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. N2 + 3 H2 → 2 NH3 If we start with 84.0 g N2 and 24.2 g of H2, what mass of ammonia can be prepared? 1. Convert each mass of reactant to moles using molar mass. 84 g N2 × 1 mol N2 =3.00 mol N2 28.01 g N2 24.2 g H2 × 1 mol H2 =12.00 mol H2 2.016 g H2 2. Identify the limiting reactant by dividing each amount in moles by the stoichiometric coefficient for that reactant. 12.0 mol H2 =4 3 mol H2 3.00 mol N2 =3 1 mol N2 3. The reactant with the smaller reaction will be the limiting reactant. N2 in this case. Use the moles of N2 to calculate the mass of the NH3 produced. 3.00 mol N2 × 2 mol NH3 17.03 g NH3 × = 102. g NH3 1 mol N2 1 mol NH3 Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Table of Amounts Organizes data, and summarizes the calculations of a stoichiometry problem Reaction N2 Starting amount (mol) 3.00 Change in amount (mol) -3.00 Final amount (mol) 0 Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. + 3 H2 12.0 -9.00 3.0 → 2 NH3 0 +6.00 +6.00 Example 1 - 16 Nitric acid, a leading industrial chemical, is used in the production of fertilizers and explosives. One step in the industrial production of nitric acid is the reaction of ammonia with molecular oxygen to form nitrogen oxide: 4 NH3 + 5 O2 → 4 NO + 6 H2O In a study of this reaction, a chemist mixed 125 g of ammonia with 256 g of oxygen and allowed them to react to completion. What masses of NO and H2O were produced, and what mass of which reactant was left over? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Example 1 - 17 The synthesis of aspirin appears in Section Exercise 1.9.3: Suppose a chemist started with 152 g of salicylic acid and 86.8 g of acetic anhydride and produced 133 g of aspirin. What is the yield of this reaction? Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Chapter 1 Visual Summary Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Chapter 1 Visual Summary Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Chapter 1 Visual Summary Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Chapter 1 Visual Summary Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Chapter 1 Visual Summary Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Chapter 1 Visual Summary Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Chapter 1 Visual Summary Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Chapter 1 Visual Summary Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Chapter 1 Visual Summary Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd. Chapter 1 Visual Summary Chemistry, 2nd Canadian Edition ©2013 John Wiley & Sons Canada, Ltd.