Chemistry Study Guide (Exam 2)

Examination 2 Chapters 4,5, and 6 reckon Guide Chapter 4 Chemical Quantities and Aqueous chemical reactions * Reactions Stoichiometry * gram moleculee-mole conversions * mass-mass conversions * limiting Reactants * What is the pass Reagent * How do we find the L. R. * settlements * Molarity comment and how to calculate * Dilutions Calculations (M1V1 = M2V2, c atomic number 18ful with M2) * Solution Stoichiometry * raft-book conversions * volume-mass conversions * molecular(a) variant of solubility * solubility rules * rush Reactions * Determining response products * Following solvability rules Molecular Formula, Total noggin formula, net garret formula * Acid-Base Reactions * oxidoreduction reactions * give a behavior odixation states * Identify which species was oxidized and cut down Chapter 5 liquides * twitch description * Simple gun for hire virtues * Boyles righteousness pV * Charless justness P/T * Avogadros truth nT * warning Gas legalitys * pV =nRT * parsimoniousness calculations * Molar plentifulness calculations * Molar intensiveness * firearmial tone Pressures * Daltons Law of Partial Pressures * Eudometer calculations * Gas Reaction Stoichiometry * script moles conversions * Kinetic Molecular speculation * 4 roles of the supposition * You DO NOT need to distinguish the derivation of I.G. L. * Effusion of Gases * Real Gases * van der Waals equality * Your extra credit brain exit hurt to do with this topic * asynchronous transfer modeospheric Chemistry * 3 types of pollution-very, very basic skepticism Chapter 6 Thermochemistry * spirit of Energy * System versus environs * Definition of Energy, upcountry heftiness, law of conservation of qualification * 1st Law of Thermodynamics * ? E = q + w * Sign convention, (is it positive or negative) * Heat and die * pV subject atomic number 18a * m Cs ? T warming transfer * conservation of thermal aptitude * Calorimetry * uninterrupted volume calorim etry * only warmth contributes to ? E * total heat * Definition, comp atomic number 18 Calculation utilize unalterable instancy calorimetry * energy-releasing versus Endothermic reactions (sign of ? H) * Hesss Law * Enthalpy of reactions manipulations * This is a hard topic, please, please, please reappraisal this after Wednesday Examination 2 Chapters 4, 5, and 6 sphere Guide Chapter 4 Chemical Quantities and Aqueous Reactions * Reactions Stoichiometry * mole-mole conversions * demand a balanced chemical equation * ** once again no clear-cut examples. tout ensembleow me jazz if you toilet find any** * mass-mass conversions * **No clear examples. Let me know if you potbelly find any** * Limiting Reactants * What is the Limiting Reagent The limiting reagent is similarly known as the limiting reactant. It is the reactant that limits the summation of product in a chemical reaction. Notice that the limiting reactant is the reactant that makes the least nitty-gritty of product. * How do we find the L. R. * example * How many grams of N2 (g) can be produced from 9. 05 g of NH3 (g) reacting with 45. 2 g of CuO (s)? attain and Balance a Chemical Equation 2NH3 (g) + 3CuO (g) N2 (g) + 3Cu (S) + 3water system (l) 9. 05 g NH3 x 1 mol NH3 x 1 mol N2 x 28. 02 N2 = (7. 44 g N2) 17. 04 g NH3 2 mol NH3 1 mol N2 45. 2 g CuO x 1 mol CuO x 1 mol N2 x 28. 2 N2 = (5. 31 g N2 Less = LR Cuo is the Limiting Reactant * Solutions * Morality definition and how to calculate * Definition * Amount of solute (in moles) per amount of closure (in Liters) * Molarity (M) = Amount of Solute (in moles) Amount of Solution (in L) * ** spot Note** * Homogenous Mixture = solutions (Salt Water) * Solvent (a grammatical constituent in a solution) Majority component, what something is fade away in. (Water) * Solute (another component in a solution) Minority component, what is being dissolved (salt) * mannequin What is the grinderity of a solution containing 3. 4 g of NH3 (l) in 200. 00 mL of solution? presumption 3. 4 g of NH3M = moles of solute (NH3) 200. 00 mL L of Solution (200. 00 mL) Convert 3. 4 g NH3 X 1 mol NH3 = (0. 20 mols NH3) 17. 04 G nh3 200 mL X 1 L = (0. 2L) 1000 mL M = 0. 20 mols NH3 / 0. 2 L = 1. 0 M NH3 **More examples in Notes ** * Dilutions Calculations (M1V1 = M2V2, careful with M2) * Diluting a solution is a common practice and the quash of moles of solute will not change (M1)(V1) = (M2)(V2) * slips What is the concentration of a solution prepared by diluting 45. mL of 8. 25 M HNO3 to 135. 0 mL? M1V1 = M2V2 8. 25 M HNO3 X 0. 045 L = M2 X 0. 135 L 0. 135 L 0. 135 L M2 = 275 M HNO3 * Solution Stoichiometry * volume-volume conversions * When using morality, you can easily purify moles * With a balance chemical equation, you can transfer between amounts of substances. * Exampes Look at notes OR paginate 145 TB * volume-mass conversions * Examples Look at notes OR page 145 TB * **This wasnt clear and If you know what this means, let me know. Or else I will ask Donavan on Saturday (Because there wasnt a limited section for the two bullet points) Molecular interpretation of solubility * solubility rules be acquainted(predicate) with the chart/table that Prof. Donavan gave out 2 synergistic violences that affect solubility 1. solute-solute interaction 2. solute-solvent interaction if solute-solvent interactions are strong enough, solute will dissolve (solute-solvent interaction solute-solute interaction) * Precipitation Reactions * Determining reaction products General Form AX (aq) + BY (aq) AY (aq) + BX (s) Example 2KI (aq) + Pb (NO3)2 (aq) 2KNO3 (aq) + PbI2 (s) * Following Solubility rules Molecular Formula, Total loft formula, net ionic formula Examples Molecular Formula 2KOH (aq) + Mg(NO3)2 (aq) 2KNO3 (aq) + Mg(OH)2 (s) Total ionic formula * 2K+ (aq) + 2(OH) (aq) + Mg2+ (aq) + 2(NO3) (aq) 2K+ (aq) + 2(NO3)- (aq) + Mg(OH)2(s) Net Ionic formula (remove all spectator ions ions that are aqueous as reactants and tolerate aqueous when they turn into products) Mg2+(aq) + 2(OH)-(aq) Mg(OH)2(s) * Acid-Base Reactions General Form HA (aq) + BOH (aq) H2O (l) + BA (aq) Example HCl (aq) + NaOH (aq) H2O (l) + NaCl (aq) * oxidization-Reduction reactions Oxidation is the loss of electrons * Reduction is the gain of electrons * Oxidation states hinge upons that allow us to keep track of electrons in chemical reactions * Identify oxidation states 1. Charge states of torpid compounds are zero 2. Charge of atoms in polyatomic ions need to add up to the total charge of the polyatomic 3. pull through Alkali metals as +1 alkali earth metals as +2 4. Keep F (fluorines) as -1 H as +1 O as -2 * Identify which species was oxidized and reduced * Look in last section of Chapter 4 Notes Chapter 5 Gases * Pressure definition Pressure The force per unit area * Pressure comes from the constant interaction with a container * Standard Pressure = Normal atmospherical Pressure * 760. 0 mm Hg = 1 a tmosphere * 760. 0 millimeter of mercury = 1 atm * 1. 000 atm * 101, 325 pa (pascals) = 1 atm * 14. 7 psi (lbs per square inch) = 1 atm * Example * (45. 0 psi) x (101, 325 pa) x (1 k pa) _____________________________ = 310. kPa (14. 7 psi) x (1000 pa) * Simple Gas Laws * Boyles Law pV * The volume of a tout inversely proportionate to its stuff, provided the temperature and measuring rod of gas dont change. * V= k/p Actual Equation pV= K * Example A balloon is put in a bell jar and the pressure is reduced from 782 millimeter of mercury to 0. vitamin D atm. If the volume of the balloon is now 2. 78 x 103 mL, what was it originally? V1 = 782 torr x 1. 000 atm/760 torr = 1. 03 atm (1. 03 atm)(V1) = (. 500 atms)(2. 78 x 103 mL) after(prenominal) Rearranging the equation V1= 1350 mL or 1. 35 x 103 mL * Charless Law P/T * The volume of a gas is diretly comparative to its temperature, provided the pressure and mensuration of the gas that dont change. (V= KT) **Temp in Kelvin On ly** * For changes in Volume (involving temperature) * V1/T1 = V2/T2 For Changes in Pressure * P/T (initial) = P/T (final) * Example (LOOK IN NOTES ) * Avogadros Law nT * The volume of a gas is directly proportional to the quantity of gas, provided the pressure and temperature of the gas dont change. (V=Kn) * For changes in volume (involving moles) * V1/n1 = V2/n2 * Example (LOOK IN NOTES ) * high-minded Gas Laws * pV=nRT * NEED TO KNOW THIS FORMULA * P = pressure (atm) * V = volume (L) * n = quantity (moles) * T = temperature (K) * R = Universal Gas Constant * (0. 08206 Latm/molK) OR * (8. 314 J/molK) * Example (look in notes ) Density calculations * Density of a gas STP * For an Ideal gas STP, the molar volume = 22. 7 L * Density = mass/volume = mass/1mole = molar mass/molar volum * volume/1mole * Density for a gas NOT STP * If gas isnt at stp * Then D = P(MM)/ RT or D = m/v * Molar Mass calculations * From the equations pV = mRT/MM You get MM = mRT/ pV * Example (Look in not es ) * Molar Volume * At STP, all holy person gases play up the same volume. * Molar Volume = of L of gas 1 mole of gas This also lops V/n = RT/P * Partial Pressures Daltons Law of Partial Pressures * The total pressure of a mixture of gases is the sum of the pressures by distributively gas. * The pressure of a gas would exert if it were whole in a container. * You can calculate the Partial Pressure from Ideal gas Law * If 2 gases , A and B are mixed unitedly * P(A) = (nA)(R)(T)/ (V) and P(B) = (nB)(R)(T)/ (V) * Since R, T, and V are all constant for a mixture * P(total) = P(A) + P(B) = (nTotal)(R)(T)/ (V) * nTotal = sum of nA + nB * Example (Look in notes ) Eudiometer calculations * An Eudiometer is a gas collecting subway * Example 2Zn (s) + 6HCl (aq) 3H2 (g) + 2ZnCl3 (aq) H20 (l) H2O (g) P(total) = P(H2) + P(H20) (value may be looked up at table 5. 4) * 0. 12 moles of Hz is still over H20 in a total 10. 0 L container at 323 K. take in the total pressure. P = nRT/V P(H2) = (0. 12 mol H2) (0. 08206 Latm/molK) (323 K)= 0. 3181 am (10. 0L) P(total) = P(H2) + P(H20) P(H2O) 50 degrees Celsius = 92. 6 mmHg P(total) = 240mmHg + 96. 6mmHg = 330mmHg * Gas Reaction Stoichiometry * General pattern plan on most problems P, V, T of Gas A Amount A (in moles) Amount B (in moles) P, V, T of Gas B * Volume moles conversions * Ex Methanol CH3OH can be synthesised by the interest reaction * CO2 (g) + 2H2(g) CH3OH(g) * What is the volume (in liters) of hydrogen gas a temperature of 355 K and pressure of 738 mmHG, is required to synthesize 35. 7 g of methanol * Given 35. 7 g CH3OH temp 355 K pressure 738 mmHG * Find V of H2 * 1. G of CH3OH mols * 35. 7g CH3OH x 1 mol CH3OH = 1. 1142 mol CH3OH 31. 04 g CH3OH * 2. Mol CH3OH mol H2 * 1. 11 mol CH3OH x 2 mols H2 = 2. 23 mols H2 1 mol CH3OH 3. N(mol H2), P, T VH2 * Convert your mmhg to ATM, and get . 971 atm * VH2= (2. 23 mol H2) (. 08206 l atm/ mol K) (355 K) = 66. 9 L .971 atm * VH2= 66. 9 L * Kinetic Molecular Theor y * In this theory a gas is modeled as a collection of subdivisions (either molecules or atoms depending on the gas ) in constant motion. * Ex, a single particle moves in a straight line until it collides with another particle (or with the walls of its container). * 4 components of the theory 1. Particles are infinitely petite and have no volume 2. Average energizing energy of a particle is proportional to the temperature (k). . Particles strike in two straight lines following Newtonian Laws 4. All collisions are elastic (no attractive or repulsive forces) * You DO NOT need to know the derivation of I. G. L. * Effusion of Gases * Effusion the process by which a gas escapes from a container into a vacuity through a small hole. * The rate of flare-up (the amount of gas that effuses in an amount of time) is also related to the root mean square focal ratio * Rate is ? 1M * Grahms law of magnification * The ratio of effusion rates of two different gases. * For example (look in note s, end of chapter 5) Real Gases * van der Waals equation is an equation utilize to correct for the discrepancies from the Kinetic Molecular Theory that echt gases undergo. Real gases attract each other, therefore, real pressure ideal pressure. Real gases also take up space, therefore, real volume ideal volume. P + a (n/v)? x (V nb) = nRT where a corrects for molecular interaction. It makes the real pressure larger so it equals the ideal pressure b corrects for molecular size. It decreases the volume of the container. * Your extra credit question will have to do with this topic * Atmospheric Chemistry 3 types of pollution-very, very basic question * 3 types of pollution-very, very basic question 1. Hydrocarbon burning for automobiles 2C8H18 + 2SO2 16CO2 + 18 H2O At high temperature, atomic number 7 can also be combusted, which causes a problem. N2 + O2 2NO 2NO + O2 2NO2 (nitrogen dioxide) photochemical smog (causes problem in the environment) 2. Combustion of coal from power plants (Ex. Electrical cars) C + O2 CO2 (Coal contains a significant amount of sulfur and it further combusts) S8 + 8O2 2SO3 2SO2 + O2 2SO3 SO3 + H2O H2SO4 (H2SO4 results to acidification)But, people have found a way to eliminate the production of SO3 and that is by using foot coal and scrubbers. CaCO3 + SO2 CaO + CO2 CaO + SO2 CaSO3 (s) (calcium sulfite) 3. Stratospheric Ozone O3 + UV O2 + O (oxygen radical) O2 + O O3 + IR These two equations above just shows how ozone is used and how it is just regenerated again. But, in 1974, Sherwood Rowland discovered that CFCs from air conditioners, refrigerators, and disperse cans destroy the atmospheric ozone. CF2Cl2 + UV CF2Cl + Cl (chlorine radical) Cl + O3 + UV O2 + ClO ClO + O O2 + Cl ( 1 Cl radical can destroy a atomic number 6 thousands of ozone)Practice testanswer keyChapter 6 Thermochemistry * reputation of Energy * System versus Surroundings System the part of the universe we want to focus on (like a chemical reaction inside a beaker) Surrounding everything else in the universe (like the glass of the beaker and the air approximately it) * Definition of Energy, internal energy, law of conservation of energy Energy is classified into two types a. horniness (q) energy transferred that causes a temperature change (due to a change in the random motion of molecules) b. work (w) energy transferred that causes an object lens to move (due to a change in the project motion of the molecules in the object) c. nits of energy I. Joule (J) the amount of energy it take to move 1kg mass a distance of 1 meter (unit kg*m2/s2) II. gram calorie (cal) the amount of energy needed to raise the temperature of 1 gram of water by 1 ? C 1 kcal = 1000 cal (food calories) 1 cal = 4. 184 J (exact measurement) innate Energy total energy of a system. (Esystem) Law of conservation of energy energy is neither created or destroyed, only transferred. * 1st Law of Thermodynamics The change in energy of a system is equal to heat that enters the system plus the work done on the system. * ? E = q + w a. ?E = change in the internal energy of a system E is (+) if the energy is absorbed by the system ?E is (-) if the energy is released by the system b. q = heat q is (+) if the heat is absorbed by the system q is (-) if the heat is released by the system c. w = work w is (+) if the work is done on the system w is (-) if the work is done by the system on the meet * Heat and work * pV work is defined by the equation w = -p? V * m Cs ? T heat transfer q = m Cs ? T where m = mass Cs = specific heat capacity (J/ g ? C) ?T = (Tfinal Tinitial) q = n Cm ? T where n = number of moles Cm = molar heat capacity (J/ mol ? C) ?T = (Tfinal Tinitial) conservation of thermal energy the amount of energy that is given must be equal with turnabout sign to that energy that is being taken. qsurr = (qsys) msurr Cs(surr) ? T(surr) = -msys Cs(sys) ? Tsys * Calorimetry * Constant volume calorimetry * Constant vo lume calorimetry bomb calorimetry, no pv work done, therefore only heat contributes to ? E qcal = Ccal ? T = -qrxn where Ccal = calorimeter constant (KJ/ ? C) * * only heat contributes to ? E * Enthalpy * Definition, equation Enthalpy (? H) the heat absorbed or released during a process taking place at a constant external pressure. ?H = qrxn = -qsurr ?H = -( m Cs ? T) Calculation using constant pressure calorimetry refer to example in notes * Exothermic versus Endothermic reactions (sign of ? H) Endothermic reactions have (+) ? H because they are reactions that absorb heat. Exothermic reactions have (-) ? H because they are reactions that give off heat. * Hesss Law * Enthalpy of reactions manipulations 2 rules to remember 1. If a reaction is reversed, the sign of ? H flips (from negative to positive or from positive to negative) 2. If you regurgitate coefficients by a number, ? H is also cypher by that number. * This is a hard topic, please, please, please analyze this after W ednesday