1 SEMESTER 1 FINAL EXAM REVIEW Unit I – Chemical Foundations I. Good things to know: chemistry scientific method: hypothesis, data, theory, variables matter substances: elements, compounds; mixtures: homogeneous, heterogeneous graphing: x-axis, independent variable; y-axis, dependent variable graphing: directly proportional, inversely proportional commonly used lab equipment and how to use properly lab safety, hazard symbols significant figures their importance in measurement scientific notation: base, power where are the sig figs? accuracy vs. precision SI system: what are the base units? what units are appropriate in what situations? density; intensive properties II. Problems _______________________ 1) Which of the following would be considered proper laboratory procedure? a. determining the odor of a substance by gently wafting the vapors if you know the substance is not harmful b. weighing a crucible while it is still hot c. measuring a liquid in a graduated cylinder by taking a reading from the top of the liquid d. rinsing a pipet with the test solution before performing a titration e. using a pipet bulb to draw liquid into a pipet f. pulling your goggles up briefly to rub your eyes g. measuring the volume of a liquid in a beaker h. diluting sulfuric acid by measuring out the desired amount of water, and then slowly pouring the concentrated acid to the water 2). How many sig figs in the following numbers? _______ a) 0.003 3) ________ b) 10.0 51348 . 10 30 6.012 10 6.938 10 34 5) 687 mg = ? kg 3 ________ c) 550 4) 6) 80.10 km = ? um _________ d) 310.01 13,4300.0235 40.017240.01 5 7) 4.01 x 10 J = ? kJ 8) You are in Paris and want to buy some peaches for lunch. The sign on the fruit stand says that peaches cost 4.00 euros per kilogram. Assuming that there are 1.14 euros to the dollar, calculate the cost of a pound of peaches in dollars. 9) If the speed of light is approximately 3.00x 10 8 m/s, what is the approximate speed in miles/hr? SEMESTER 1 FINAL EXAM REVIEW 2 10) If you have a graduated cylinder which initially contains 15.7 mL of water, and when a 65.64 g object is placed inside, shows a new volume of 22.6 mL, what is the object’s density? 11) The approximate mass of the earth is 5.94 x 10 21 metric tons. If the circumference of the Earth at the equator is approximately 25,000 miles, what is the approximate density of the earth in g/mL ? Vsphere = 4/3 πr3 C = 2πr 1 metric ton = 1000 kg Unit II – Atomic Theory & The Periodic Table 1. Explain the Photoelectric effect as it pertains to quantam theory: Why is it that purple light will expel electrons from a piece of metal, but red light will not? Why is it that as the intensity of the light increases, the expelled electrons do not become more energetic, there are simply more of them expelled? 2. Briefly describe the concept of DeBroglie’s Equation. How does the wavelength vary with mass? 3. Briefly describe Bohr’s Atomic Theory for the hydrogen atom. What phenomenon gave rise to his theory? How do the colors of the bright-line spectra for hydrogen relate to the Energy levels in a hydrogen atom? 4. Explain why adding an electron to a fluorine atom is an exothermic process. 5. Explain why adding an electron to a neon atom is an endothermic process. 3 SEMESTER 1 FINAL EXAM REVIEW 6. Explain the trend in atomic radius from Li to Na to K. 7. Explain the trend in atomic radius from Na to Mg to Al. 8. Explain the trend in first ionization energy from Na to Mg to Al. 9. Explain why the 2nd ionization energy for sodium is so much greater than that for magnesium. 10. What would the first two quantum numbers be for an electron in a 4f subshell? How many possible quantum number sets are there for a 4f subshell? Give two examples. How many electrons can be held in the entire 4th energy level? 11. Fill in the table below Element Family Name # of Valence Electrons Potassium Magnesium Cadmium Dysprosium Chlorine Neon XX XX Physical State (metal, nonmetal, metalloid) Electron Configuration Paramagnetic or Diamagnetic? 4 SEMESTER 1 FINAL EXAM REVIEW _______ 12. Which of the following could be the quantum numbers for the valence electron in a ground state sodium atom? a. (3,0,0,½) b. (3,1,1,½) c. (4,0,0,½) d. (4,1,1,½) e. (4,2,1,½) _______ 13. Which of the following is an impossible set of quantum numbers? Explain your answer. a. (3,0,0,½) b. (3,1,1,-½) c. (3,1,-2,½) d. (3,2,-1,½) e. (3,2,2,½) 14. Which fundamental atomic theory is violated by the following list of quantum numbers representing silicon’s 4 valence electrons? (3,0,0,-½), (3,0,0,-½), (3,1,1,-½), (3,1,1,-½) 15. Which fundamental atomic theory is violated by the following list of quantum numbers representing silicon’s 4 valence electrons? (3,0,0,-½), (3,0,0,+½), (3,1,-1,-½), (3,1,-1,+½) 16. Which of the following atoms or ions is larger: ______ a. sulfur or sulfide ______ b. sodium atoms or sodium ions ______ c. Na or K ______ d. S or Cl ______ e. Na+ or Mg+2 ______ f. F-1 or Cl-1 17. Explain why a fluorine atom gains in size when it accepts an electron to become a fluoride ion. 18. Give the number of protons, neutrons, and electrons in the following: a) 131 54 Xe b) 56 26 Fe 3 c) 127 53 I 1 ______ protons ______ protons ______ protons ______ neutrons ______ neutrons ______ neutrons ______ electrons ______ electrons ______ electrons SEMESTER 1 FINAL EXAM REVIEW Unit III – Nomenclature & Chemical Equations 1) Give the name or formula for the following: _____________ a. sulfuric acid __________________________________ k. NH3 _____________ b. calcium hydroxide __________________________________ l. NiS _____________ c. xenon hexafluoride __________________________________ m. (NH 4)2CO3 _____________ d. iron(II) dichromate __________________________________ n. AlCl3 _____________ e. hydrocyanic acid __________________________________ o. Cr(OH)3 _____________ f. rubidium oxide __________________________________ p. CCl4 _____________ g. sodium phosphite __________________________________ q. Fe2(C2O4)3 _____________ h. tin(IV) phosphate __________________________________ r. HC2H3O2 _____________ i. carbon monoxide __________________________________ s. NaH _____________ j. barium sulfate octohydrate __________________________________ t. MgF2 2. Write the formulas to show the reactants and products for any FIVE of the laboratory situations described below. In all cases, a reaction occurs. Assume that all solutions are aqueous unless otherwise indicated. Represent substances in solution as ions if the substances are extensively ionized. Omit formulas for any ions or molecules that are unchanged by the reaction. You need not balance the equations. a. b. c. d. e. f. g. h. A bar of nickel metal is placed in a solution of copper(II) sulfate. Solid sodium hydride is added to water. Propanone (C3H6O) is burned in air. A solution of lead(II) nitrate is added to a solution of potassium sulfate. A solution of ammonia is mixed with a solution of acetic acid. Sulfur trioxide gas is bubble into water. Excess concentrated potassium cyanide solution is added to a solution of nickel chloride. Solid sodium acetate is added to 1.0M hydrobromic acid. 5 SEMESTER 1 FINAL EXAM REVIEW 6 Unit IV – Stoichiometry I. Good things to know stoichiometry, chemical formula ionic compound formula unit hydrate, anhydrous molecular compound molecule mole, Avagadro’s Number formula mass, molar mass, molecular mass Standard Temperature and Pressure (STP) percent yield limiting reactant, excess reactant Law of Definite Proportions, Law of Multiple Proportions empirical formula, molecular formula mass spectrometer titration, standard solution, unknown solution II. Problems 1) Calculate the number of moles of HF molecules in: a) 0.385 g HF b) 3.02 x 1024 molecules of HF c) 50.0 mL of a 0.600M HF solution d) 1.50L of HF at 0.989 atm of pressure and 23.1oC 2) Answer the following questions using the following equation: ____ HF(g) + ____ SiO2(s) ____ SiF4(s) + ____ H2O(l) a) balance the equation b) How many grams of silicon tetrafluoride will you get if you react 5.00g of silicon dioxide with excess HF? c) How many grams of silicon tetrafluoride will you get if you react 5.00g of silicon dioxide with 5.00g of HF? How many grams of the excess reactant will be left over? d) If you actually produce 5.92g of silicon tetrafluoride in problem (c), what is the percent yield? SEMESTER 1 FINAL EXAM REVIEW 3) A sample of 0.6760g of an unknown compound containing barium ions (Ba +2) is dissolved in water and treated with an excess of Na2SO4. If the mass of the barium sulfate precipitate formed is 0.4105g, what is the percent by mass of barium in the original unknown compound? 4) A hydrocarbon was found to be 20% hydrogen by weight. If one mole of the hydrocarbon has a mass of 30 grams, what is its molecular formula? 5) If you add 20.0 mL of 0.100 M iron(III) nitrate to 20.0 mL of 0.100 sodium hydroxide, how many grams of precipitate will be formed? Write the net ionic equation for the reaction. 6) If it requires 25.0 L of a 0.500M KI solution to precipitate all of the lead(II) ions out of a 100.0 mL sample, what is the concentration of the lead ions? 7) What is the concentration of an unknown H2SO4 solution if it requires 156.3 mL of 1.50M NaOH standard to titrate a 100.0 mL sample of the unknown? 8) In your lab, you titrated hydrogen peroxide with potassium permanganate: 6 H+ + 2 MnO4- + 5 H2O2 5 O2 + 2 Mn+2 + 8 H2O If 36.44 mL of a 0.01652 M KMnO4 solution is required to completely oxidize 25.00 mL of a H2O2 solution, calculate the molarity of the peroxide solution. 7 8 SEMESTER 1 FINAL EXAM REVIEW Unit V – Bonding I. Good things to know ionic bonding Coulomb’s Law covalent bonds lone pair, shared pair stable octet polar vs. nonpolar, dipole moment sigma bond, pi bond formal charge, bond length resonance hybrid orbitals, VSEPR model organic chemistry 4 allotropes of carbon saturated and unsaturated hydrocarbons functional groups – hydroxyl, ethers, aldehydes, ketones, organic acids, esters, amines isomers, polymers aromatic compounds II. Problems 1) Which of the following ionic compounds would you expect to have the higher melting point? Explain. a. NaCl vs. KBr 2) Put the following molecules in order of their C – O bond length. Explain. CH3OH CO2 CO3-2 5) For each of the following, give the Lewis Structure, type of hybrid orbitals used by the molecule, shape, polarity, bond angle, and number of sigma and pi bonds: a. PCl3 d. BrF5 c. NO3-1 b. CO2 e. PF5 9 SEMESTER 1 FINAL EXAM REVIEW 6) Without using the table of bond energies, which of the following molecules would you expect to require the most energy to break its C – C bonds? Explain your answer. C2H6 C2H4 C2H2 7) Give the IUPAC name for the following: CH3 CH3 CH3 CH CH 2 CH CH3 ___________________________________________ a. Br CH3 ___________________________________________ b. CH2 CH CH2 CH2 CH3 NH2 ___________________________________________ c. Br Br Unit VI – Phases & Gas Laws I. Good Stuff to Know definitions of solid, liquid, gas, fluid, condensed state Pressure - relationship between force and area barometer - atmospheric pressure, air pressure, barometric pressure standard temperature and pressure (STP): 1 atm = 76θ Torr = 76θ mmHg = 101.3 kPa and 273K manometer vaporization – boiling (how does it relate to vapor pressure?), evaporation amorphous solid- example crystal lattice – crystals o density of solids, liquids, gases - water (most dense at 4 C) intermolecular forces: dipole-dipole interactions, London Dispersion Forces, hydrogen bonding, ionic crystals, network solid. metallic crystals Phase Diagrams – melting, freezing, boiling, condensation, sublimation, deposition Phase Diagrams - triple point, critical temperature, unique properties of water substances that exist as gases Avogadro’s Law Kinetic Theory use it to explain Boyle’s Law, Charles’ Law, Avogadro’s Law, Dalton’s Law, compressibility of gases root-mean-square speed, mean free path diffusion vs. effusion deviations from ideal behavior, vanderWaal’s equation 10 SEMESTER 1 FINAL EXAM REVIEW II. Multiple Choice For questions 1-4, select from the following answers a. metallic bonding b. network covalent bonding d. ionic bonding e. London Dispersion Forces c. hydrogen bonding ______ 1. Nonpolar substances such as methane (CH4) demonstrate this type of bonding. ______ 2. This kind of bonding is exhibited by diamond and quartz, and explains their hardness and extremely high melting points. ______ 3. This type of bonding is only exhibited by ammonia, water, and hydrogen fluoride, and results in these substances having unusually high melting and boiling points. ______ 4. This type of bonding results in solids that are poor conductors of heat and electricity, but which, when melted, are good conductors of electricity. Questions 5-8 refer to the following phase diagram: ______ 5. At this point the substance represented by the phase diagram will be solely in the solid phase at equilibrium. ______ 6. This point represents the boiling point of the substance. ______ 7. At this point, the substance represented by the phase diagram could be undergoing sublimation. ______ 8. At this point the substance represented by the phase diagram will be solely in the liquid phase at equilibrium. ______ 9. Which of the following lists of species is in order of increasing boiling point? a. H2 , N2 , NH3 b. N2, NH3, H2 c. NH3, H2, N2 d. NH3, N2, H2 e. H2, NH3, N2 III. Essay/Problems 1. Explain why the boiling point of argon is -186oC, but the boiling point of neon is -246oC. 2) What is the pressure of the gas in the enclosed container? P = 1.27 atm 243 mm SEMESTER 1 FINAL EXAM REVIEW 11 3) Consider three identical flasks filled with different gases: Flask A: CO at 760 Torr and 0oC Flask B: N2 at 250 Torr and 0oC Flask C: H2 at 100 Torr and 0oC ______a. In which flask will the molecules have the greatest average kinetic energy? ______ b. In which flask will the molecules have the greatest average velocity? o 4) A gas occupies a volume of 34.2 mL at a temperature of 15.0 C and a pressure of 800.0 Torr. What will the volume of this gas be at STP? 5) Find the formula mass of a gas which diffuses at a rate 1.16 times faster than that of sulfur dioxide gas. o 6) 40.0 mL of helium gas is collected over water at 20.0 C. If this gas exerts a pressure of 790.0 Torr, what would the volume of the dry gas be at STP? (Remember this is a mixture of two gases: water vapor o and helium) (Pwater = 17.54 mmHg at 20.0 C) o 7) What is the density of oxygen gas collected at 21.0 C and 103.5 kPa? 8) If you collected 0.506 g of a gas which you know to be composed of 30.4% nitrogen and 69.6% oxygen, o and it occupied a volume of 0.134 L at a temperature of 2θ C, and a pressure of 0.986 atm, what would the formula mass of the gas be? Give the molecular formula of the gas as well.