CHEM-1A-14 Exam 2 Study Guide Fall 2024 PDF

CHEM-1A-14 (Dr. Peebles) Fall 2024 Exam 2 Study Guide Exam 2 will be given in lab on Wednesday 10/23 or Thursday 10/24. The exam is designed to be completed in an hou...

CHEM-1A-14 (Dr. Peebles) Fall 2024 Exam 2 Study Guide Exam 2 will be given in lab on Wednesday 10/23 or Thursday 10/24. The exam is designed to be completed in an hour, but you will have 90 minutes to complete it. Please arrive 15 minutes early to class that day, if possible, so you can get started with the exam promptly at the start of class. If you arrive late, you will not be allowed extra time. The exam will cover Chapters 4.4-8.4 (first part of 8.4) of the Tro textbook. (The rest of Chapter 8 will be on Exam 3.) Bring with you: a scientific or graphing calculator (NOT YOUR PHONE) your CSUS ID card YOU DO NOT NEED A SCANTRON FORM. Your instructor will provide: a periodic table any conversion factors that are not for SI units (including SI to non-SI pressure and energy units) any SI conversion factors that are larger than Mega or smaller than micro the values of Avogadro’s number and any other constants, such as R, c and h, that you may need any values that would normally be looked up in a table (such as values for CS and ΔHf° ) Format: The first part of the exam will consist of about 35 multiple choice questions (some partial credit available). There will be 2-4 short-answer type questions, such as matching, fill in the blank, true/false, etc. There will be 2-3 longer answer problems. You should practice and rework problems from your Discussion worksheets, Mastering Chemistry assignments (both the graded and practice ones), BSQ2 and BSQ3 preparation worksheets, and any other written work from this class, as practice for the exam. An additional worksheet of Exam 2 practice problems has also been posted (answers will be provided later) on Canvas. All of these sources have good examples of the types of questions that you are likely to encounter on the exam. The Pearson page has a lot of good practice and help materials, too. The best way to prepare is to do lots of practice problems – you need actually to work out the questions and not just look at them and decide that you understand how to do them. Multiple choice questions will mostly cover conceptual material and more basic understanding, so you should also go over your notes and the textbook chapters to fill in any gaps in your understanding from the topics listed on the study guide. Below is a list of important topics to guide your studying, although anything covered in class could turn up on the exam. Chapter 4 Be able to write chemical reaction equations when given a description of the reaction in words. Be comfortable balancing chemical reactions. Understand why this is required by the Law of Conservation of Mass. Understand the differences between subscripts in a chemical formula and the stoichiometric coefficients that are written in front of a formula when balancing equations. Understand the concepts of reactants and products. Be able to perform calculations that involve relating the numbers of moles of different reactants and/or products to each other via the balanced reaction equation. These are known as stoichiometry calculations. This is another key concept this semester and in addition to being covered on Exam 1, it will be the focus of Basic Skills Quiz #4.  In addition to relating moles to moles via a reaction, be able to use the idea of molar mass to relate masses of reactants and products to each other (i.e. calculate mass of product formed from a given mass of reactant, for example). START OF EXAM 2 MATERIAL IS HERE Understand the concept of limiting reactants and be able to determine the limiting reactant of a reaction if you are given starting amounts of all reactants. Understand the ideas of theoretical yield and percent yield, and be able to calculate these for a reaction. (For percent yield, you must be told what the actual amount of product formed in the reaction was, or you must have data from a lab experiment.) Know what a combustion reaction is (burning) and be able to write a balanced combustion reaction if you are told the one reactant that is undergoing combustion. You need to know what other reactant(s) and products will be involved, their appropriate states, and be able to balance the equation. You do not need to know the alkali metal and halogen reactions that are discussed at the end of Chapter 4 at this time. Stoichiometry and limiting reactants are both important in this and subsequent chemistry courses, and they are challenging problems that require a lot of practice (just like playing a sport or an instrument or becoming skilled in a craft or trade). There are lots of extra practice problems in the Chapter 4 Mastering practice assignment, and working these and being sure you understand any errors you are making should be a big boost towards solidifying your chemistry problem solving skills. Chapter 5 Know and understand the terms solution, solvent, solute, and concentration. Know what an aqueous solution is. Know what the terms concentrated and dilute mean in relation to solution concentrations. Know the mathematical definition of molarity and be able to calculate molarities from grams or moles of solute and volume of solution. Also be able to calculate volume from molarity and moles or moles from molarity and volume. Be able to use molarity as a conversion factor in calculations that involve solutions. Use the definition of molarity to do stoichiometry calculations that start and/or end with a volume of solution instead of with grams or moles. Know and be able to apply the dilution formula, M1V1 = M2V2. Understand what the terms soluble and insoluble mean and know the solubility rules and be able to apply them to determine whether ionic compounds are soluble or insoluble in aqueous solution. The solubility rules that you need to learn for this course are given in Table 5.1. You need to know all of the rules in Table 5.1, and you must also know the exceptions to those rules that are listed in Table 5.1. Understand the differences between electrolytes and nonelectrolytes and between strong and weak electrolytes. Know which category different types of compounds fall into. Be able to write dissolution reactions for electrolytes (both strong and weak).  Be able to predict the products of precipitation reactions and be able to write balanced molecular equations for them. Know what a precipitate is. Know the difference between molecular, complete ionic and net ionic equations, and be able to write complete ionic and net ionic equations from molecular equations. Know what spectator ions are, and be able to identify them in complete ionic equations. Be able to write acid-base (i.e. neutralization) reactions, including the three types of neutralization reaction that are also classed as gas-forming reactions. Know the names and formulae of the six strong acids (HCl, HBr, HI, HNO3, H2SO4, HClO4). Be able to identify acids and bases from their formulae. Be able to distinguish between strong and weak bases based on their formulae. Know what a titration is and be able to use data from titrations to perform solution stoichiometry calculations, including using a known concentration of acid or base to determine an unknown concentration of base or acid. Know what the equivalence point in a titration is. Know what oxidation states (oxidation numbers) are and be able to determine the oxidation state of each atom in a chemical reaction. Be able to use oxidation states to determine whether a reaction is a redox reaction. Know the definitions of oxidation and reduction and relate these to the oxidation states of the atoms in a reaction. You do not need to be able to use the activity series to predict the products of redox reactions. Chapter 6 Know the definition of pressure and understand the derived SI unit of pressure. In addition to the SI unit (Pascals), be familiar with common non-SI units of pressure: bar, atmosphere, mm Hg, Torr. You DO need to know the conversions between Torr, mm Hg, and atm. You will be provided with other needed conversion factors related to pressure. Know and understand the simple relationships between pressure, volume, temperature and moles that are incorporated in Boyle’s, Charles’s, and Avogadro’s laws. I don’t care if you know the names of these laws, but you do need to know, for instance, that PV = constant (or P1V1 = P2V2), etc. Know the ideal gas equation, and be able to use it to solve problems related to the behavior of gases. You need to know what R is (i.e. it is the gas constant), but you do not need to memorize the value. It will be provided on your exam. You should be able to choose which value of R you should be using based on the units of R and the units of other information give in the question. Know what standard temperature and pressure (STP) means, and know what pressure and temperature this refers to. Be able to relate the density of a gas to its molar mass and to the ideal gas law. Understand what partial pressure and mole fraction are, and be able to relate these to the total pressure or total volume of a gas sample. Be able to solve stoichiometry problems that involve gases. This includes working out the volume of gas that would form in a reaction from a given mass of reactant, or working out amounts of products from provided information about gas phase reactants.  Know the main points of the Kinetic Molecular Theory of Gases, and understand how these lead to our ability to treat almost all gases as ideal (i.e. they all behave the same, regardless of their chemical identity). Understand that temperature is a measure of the average kinetic energy of the molecules in a gas. When the same gas feels hotter, it is because the molecules are moving faster. In a mixture of gases that are all at the same temperature, the lighter molecules are moving faster (because KE = ½ mv2, and if temperature is equal, then KE is equal, and a larger velocity is needed to combine with a smaller mass to give the equal KE). You do not need to know about mean free path, diffusion, or effusion. Understand the factors that most often lead to non-ideal behavior in gases. These are intermolecular forces and non-negligible size of the molecules. Know what the van der Waals equation is and how to interpret it. You do not need to memorize the van der Waals equation – it will be given on the exam, if it is needed. Chapter 7 Know what thermochemistry is. Know and understand the definitions if energy, heat, work, kinetic energy, thermal energy, system, surroundings. Know and understand the Law of Conservation of Energy and know that this is the same as the First Law of Thermodynamics. Understand the derived SI unit of energy (Joules, J) and know/recognize the calorie as a commonly used non-SI energy unit. On the exam you will be provided with the conversion factor to convert between Joules and calories. Also know the difference between regular calories and nutritional Calories (with a capital “C”). Know what internal energy (E) is and know the meaning and significance of a state function. Understand that internal energy and enthalpy are state functions but that heat and work are not state functions. Understand which direction of energy, enthalpy, heat and work transfer between the system and surroundings gives a negative or positive value for ΔE, ΔH, q or w. Understand the difference between heat and temperature and know that they are linked through the specific heat capacity (CS). Know the definition of specific heat capacity, and know the formula to calculate q from mass, specific heat, and temperature change (q = mCSΔT). Be able to perform calculations related to temperature change and heat transfer, including calculations related to coffee-cup calorimetry and bomb calorimetry. Know the definition of enthalpy in terms of internal energy, pressure and volume. Understand that at constant pressure, enthalpy change is equal to q, and at constant volume internal energy change is equal to q. Know the definition of pressure-volume work. Be able to calculate work done from pressure and change in volume. Know and understand the meaning of the terms exothermic and endothermic and relate these to the sign of ΔH. Understand what a thermochemical equation is. Be able to use information from thermochemical equations as stoichiometric conversion factors. Know how the ΔH value for a thermochemical equation changes when the reaction is manipulated in different ways (for instance if reactants and products are exchanged or if all the stoichiometric coefficients are doubled). Know what Hess’s Law is, and be able to use it to combine known information from thermochemical equations to calculate the ΔH value for a given reaction. Know what a formation reaction is, and be able to write formation reactions for different substances. Know what is meant by the term standard state. Understand what standard enthalpy of formation (ΔHf°) is. Be able to use tabulated ΔHf° values to calculate the enthalpy change for a given reaction. You do not need to memorize ΔHf° values – you will be provided with needed values on the exam. Chapter 8  Understand what electromagnetic radiation is. Understand what wavelength (λ), amplitude, and frequency (ν, “nu”) are. Know what the electromagnetic spectrum is. You do not need to memorize the wavelength ranges that correspond to different types of radiation in the electromagnetic spectrum. Know what the speed of light (c) is, and know and be able to use the formula that relates frequency, wavelength, and c for electromagnetic radiation. You will be given the value of c – you do not need to memorize it. Understand how waves (of electromagnetic radiation or any other type) can constructively or destructively interfere. Know, in general terms, what the photoelectric effect is. You do not need to be able to do calculations related to the photoelectric effect. Understand what is meant by the dual nature of light. Know that electromagnetic radiation has both wave-like and particle-like properties, and know that a particle of electromagnetic radiation is called a photon. Know the formula that relates the energy of a photon to its frequency. You do not need to memorize the value of Plank’s constant (h) – that will be provided. Understand what is meant when we say that energy is quantized and that the energy of the electron in an atom is quantized. Understand what an atomic emission spectrum and an atomic absorption spectrum are, what the difference is between them (in terms of how they’re formed), and how these relate to the structure of an atom and the Bohr model. Know what the Bohr model of the atom is and that this model only really works for hydrogen atoms. Understand how real atoms differ from the Bohr model. Understand the significance of the de Broglie relation and be able to calculate wavelength from mass or mass from wavelength using it. You will be provided with the formula, but you need to recognize it and be able to apply it. ***END OF EXAM 2 MATERIAL*** Know the difference between an electron orbit (Bohr model) and an orbital (real atoms). Know what the Schrödinger equation is and recognize it, but you will never need to solve it. It is just a concept that helps explain the difference between real atoms that are explained by quantum mechanics and the Bohr model. Understand the concepts described by the Heisenberg Uncertainty Principle. You only need a familiarity with the concept of the Uncertainty Principle; you will not need to solve numerical problems related to it. Know the four quantum numbers that are used to describe the specific orbital an electron occupies in an atom. Know how these four quantum numbers relate to the size, shape and orientation of an orbital, and an electron’s “spin” within the orbital. Know the allowed values of the quantum numbers relative to each other. Know how the orbital labels s, p, d, f, etc. relate to orbital shape and to the l quantum number. Be able to use the equation for the energy difference between two orbitals that is equation 8.8 in the Tro eText. You will be given the equation, if it is needed. Understand what nodes in orbitals are and be able to work out the number of nodes an orbital will have based on the n and l quantum numbers. You do not need to know anything about radial distribution functions, which were not covered in class. Know and recognize the general shapes of s, p and d orbitals. There are nice pictures in Figures 8.24, 8.27, and 8.29. The d orbitals are labelled with names like “dxy”, and you don’t need to know those.