* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chem 150 - Fall 2015 Exam I
Electron configuration wikipedia , lookup
Chemical thermodynamics wikipedia , lookup
Water pollution wikipedia , lookup
Stoichiometry wikipedia , lookup
Metastable inner-shell molecular state wikipedia , lookup
Freshwater environmental quality parameters wikipedia , lookup
Biological aspects of fluorine wikipedia , lookup
Properties of water wikipedia , lookup
Lewis acid catalysis wikipedia , lookup
Inorganic chemistry wikipedia , lookup
Nucleophilic acyl substitution wikipedia , lookup
Molecular Hamiltonian wikipedia , lookup
Molecular orbital diagram wikipedia , lookup
Debye–Hückel equation wikipedia , lookup
Resonance (chemistry) wikipedia , lookup
Hydrogen bond wikipedia , lookup
Computational chemistry wikipedia , lookup
History of chemistry wikipedia , lookup
Electrochemistry wikipedia , lookup
Periodic table wikipedia , lookup
Acid strength wikipedia , lookup
Artificial photosynthesis wikipedia , lookup
Size-exclusion chromatography wikipedia , lookup
Molecular dynamics wikipedia , lookup
Physical organic chemistry wikipedia , lookup
Extended periodic table wikipedia , lookup
Chemical bond wikipedia , lookup
Chemistry: A Volatile History wikipedia , lookup
Photosynthetic reaction centre wikipedia , lookup
IUPAC nomenclature of inorganic chemistry 2005 wikipedia , lookup
Water splitting wikipedia , lookup
Acid dissociation constant wikipedia , lookup
Atomic theory wikipedia , lookup
Nanofluidic circuitry wikipedia , lookup
Biochemistry wikipedia , lookup
History of molecular theory wikipedia , lookup
Hypervalent molecule wikipedia , lookup
Acid–base reaction wikipedia , lookup
Name __________________________________ Chem 150 - Fall 2015 Exam I • There is periodic table for you to use on the last page of the exam. • Be certain that what you hand in represents your own work. 1. For each of the following elements, indicate their number of valence electrons and the number of covent bonds they would normally form as part of molecules. No. valance electrons No. of bonds Se P C Br H 2. Draw the Lewis dot structures for the following molecules Lewis dot structure PH3 CH2O HCN 3. Which of the following compounds has the strongest dispersion force between its molecules in its pure form (circle one)? a.! b.! c.! !1 Chem 150 Exam I 4. Which Period 3 element has the lowest affinity for valence electrons? Fall, 2015 Electronegativities a. Si b. P c. S d. Cl 5. Formaldehyde is toxic because it is highly reactive with biological molecules. The molecular formula for formaldehyde is CH2O a. Draw the Lewis dot structure for hydrogen formaldehyde: b. Is formaldehyde a polar molecule? (circle one) yes / no c. If so, which atom is the more negatively charged? _______ 6. Identify each of the following compounds as either ionic or molecular (circle one). a. PF3 ionic / molecular b. (NH4)2C2O4 ionic / molecular c. BaO ionic / molecular d. NaF ionic / molecular e. CH2O ionic / molecular 7. The following molecules all have approximately the same molar mass, which is expected to have the lowest boiling point (circle one)? a. ! b. ! c. ! 8. Identify whether each of the described energies below are an example of kinetic or potential energy (circle one) a. The dispersion force that exists between molecules kinetic / potential b. When a ball is thrown straight up into the air, the energy it has as it just leaves kinetic / potential your hand c. The nutritional energy in a slice of pizza kinetic / potential d. When a ball is thrown straight up into the air, the energy it has when it reaches kinetic / potential its highest point before returning back to earth. 2 Chem 150 Exam I Fall, 2015 9. As you cool 252 mL of water from 80°C to 24°C, a. Do the average velocities of the water molecules, speed up / slow down / remain the same b. If the density of water is 1.0 g/mL, and the specific heat of water is 1.0 cal/°C-g, how many calories of heat are required to cool the 252 mL of water from 80°C to 24°C? ! c. Describe what will happen to the water if you continue to remove heat (thermal energy) from the water after it reaches 24°C d. Water (H2O) has a very high melting point compared to other molecules of similar size and composition, e.g., H2S, CH4, NH3, HF, which unlike water are all gases at room temperature. Explain why water stands out among this group 10. Which of the following compounds has the strongest dispersion force between its molecules when in its pure form (circle one)? a.! b.! c.! 11. Which of the following compounds contains a covalent bond that is strongly polar (circle one)? a. ! b. ! c. ! 3 Chem 150 Exam I Fall, 2015 12. Shown below is the structural formula for the amino acid cysteine? ! a. Circle all of the hydrogen atoms that can participate in hydrogen bonds. b. Draw a square around each of the atoms that can serve as an acceptor in a hydrogen bond. c. Draw one example of a water molecule hydrogen bonding to cysteine with the water molecule serving as the acceptor. d. Draw one example of a water molecule hydrogen bonding to cysteine with the water molecule serving as the donor. 13. Which of the following compounds is expected to be the most soluble in water (circle one)? a. ! b. ! c. ! 14. When hydrochloric acid reacts with potassium monohydrogen phosphate in solution to form potassium dihydrogen phosphate, and potassium chloride, 28.2 kcal of heat are absorbed from the surroundings per mole of potassium monohydrogen phosphate that reacts. a. If this reaction is carried out in a beaker, how does the beaker feel to the touch (circle one)? warmer / cooler / unchanged b. Using chemical formulas, write the net ionic equation for this reaction, which also includes the heat that is absorbed in the reaction. c. This is an acid base reaction. For each species in your balance chemical equation, use labels to identify the acid, the base, the conjugate acid, and the conjugate base. 15. The gasoline that is sold today can contains up to 85% ethanol (CH3-CH2-OH) by weight, which is produced from renewable sources. a. Write a balanced chemical equation for the complete combustion of ethanol to CO2 and H2O b. One ounce of ethanol weights 28.4 g. If 331 kcal of heat are released per mole of ethanol that undergoes combustion, how many kcal of heat are released from the burning of 2 ½ ounces of ethanol. ! 4 Chem 150 Exam I Fall, 2015 16. For a 0.080 M solution of potassium dihydrogen phosphate, a. What is the molar concentration of potassium ions? ! b. What is the molar concentration of dihydrogen phosphate ions ! c. What is the concentration of potassium ions in units of mEq/L? ! d. What is the concentration of dihydrogen phosphate ions in mEq/L? ! 17. A 0.400 M solution of lactic acid (HC3H5O3) is determined to have a pH of 2.15. What are the concentrations of hydronium ion (H3O+) and hydroxide ion (OH-) in this solution? a. [H3O+] = b. [OH-] = c. Is lactic acid a weak or a strong acid (circle one) weak / strong d. The conjugate base for lactic acid is the lactate ion. Write the chemical formula for the lactate ion ! e. If the pKa for lactic acid is 3.90, what is the pH of a solution made by mixing equal amounts of lactic acid and sodium lactate? pH = ! f. Explain what this solution could be used for? 5 2.1 1.0 1.2 0.9 K 0.8 37 6 1.0 0.8 1 0.7 0.7 0.9 [226] Ra ytterbium thulium erbium holmium dysprosium terbium gadolinium europium samarium promethium neodymium [294] — [293] [288] [289] [284] [285] [280] [281] 173.054(5) nobelium 102 168.93421(2) mendelevium 101 167.259(3) fermium 100 164.93032(2) einsteinium 99 162.500(1) californium 98 158.92534(2) berkelium 97 157.25(3) curium 96 151.964(1) americium 95 150.36(3) plutonium 94 [145] neptunium 93 144.24(3) uranium 92 91 [227] Pa U 231.03588(2) 238.02891(3) [237] [244] [243] [247] [247] Np Pu Am Cm Bk [251] Cf [252] [257] [258] [259] Es Fm Md No Element symbols and names: symbols, names, and spellings are recommended by IUPAC (http://www.iupac.org/). Names are not yet proposed for the elements beyond 111 - those used here are IUPAC’s temporary systematic names (Pure & Appl. Chem., 1979, 51, 381–384). In the USA and some other countries, the spellings aluminum and cesium are normal while in the UK and elsewhere the usual spelling is sulphur. Atomic weights (mean relative masses): Apart from the heaviest elements, these are IUPAC 2007 values (Pure & Appl. Chem., 2007, in press). Elements with values given in brackets have no stable nuclides and are represented by integer values for the longest-lived isotope known at the time writing. The elements thorium, protactinium, and uranium have characteristic terrestrial abundances and these are the values quoted. The last significant figure of each value is considered reliable to ±1 except where a larger uncertainty is given in parentheses. Periodic table organisation: for a justification of the positions of the elements La, Ac, Lu, and Lr in the WebElements periodic table see W.B. Jensen, “The positions of lanthanum (actinium) and lutetium (lawrencium) in the periodic table”, J. Chem. Ed., 1982, 59, 634–636. Group labels: the numeric system (1–18) used here is the current IUPAC convention. For a discussion of this and other common systems see: W.C. Fernelius and W.H. Powell, “Confusion in the periodic table of the elements”, J. Chem. Ed., 1982, 59, 504–508. ©2007 Dr Mark J Winter [WebElements Ltd and University of Sheffield]. All rights reserved. For updates to this table see http://www.webelements.com/nexus/Printable_Periodic_Table. Version date: 21 September 2007. Th 232.0381(1) Ac 70 140.90765(2) protactinium 69 Er Tm Yb 68 90 67 Dy Ho 66 140.116(1) thorium 65 89 64 138.9055(2) actinium 63 Nd Pm Sm Eu Gd Tb 62 Pr 61 Ce 60 La 59 praseodymium 58 cerium lanthanum 57 [267] Ds Rg Uub Uut Uuq Uup Uuh Uus Uuo [268] Rf Mt [276] [270] [272] [271] 118 [262] Db Sg Bh Hs [222] ununoctium 117 Rn 116 At 115 Po 114 Bi 113 Pb [209] 208.98038(2) 207.2(1) 204.3833(2) ununtrium ununquadium ununpentium ununhexium 112 200.59(2) ununbium 111 Tl 86 131.293(6) radon 54 Xe 110 109 108 107 106 105 195.078(2) 196.96655(2) darmstadtium roentgenium Lr 104 Au Hg 85 126.90447(3) astatine I 53 Kr 83.798(2) xenon [210] ununseptium Pt 84 Br 79.904(1) iodine 36 39.948(1) krypton Ar 18 20.1797(6) argon Ne 10 4.002602(2) neon He 2 helium 18 8.A Exam I Actinoids Lanthanoids [223] Fr 0.9 103 Ir 192.217(3) meitnerium 190.23(3) hassium Re Os 186.207(1) bohrium W 183.84(1) seaborgium Ta 180.9479(1) dubnium 1.8 88 Hf 1.9 87 Lu 83 1.9 178.49(2) 174.9668(1) lawrencium rutherfordium 82 127.60(3) polonium 52 Te 2.0 137.327(7) radium Cs Ba 81 80 79 78 77 76 75 74 73 72 71 121.760(1) bismuth Se 78.96(3) tellurium 35 35.453(2) bromine Cl 17 18.9984032(5) chlorine F 9 fluorine 17 2.2 132.90545(2) francium 56 1.8 118.710(7) lead 51 1.9 55 114.818(3) thallium 112.411(8) mercury 107.8682(2) gold 106.42(1) platinum 102.90550(2) iridium 101.07(2) osmium [98] rhenium 95.96(2) tungsten 92.90638(2) tantalum 91.224(2) hafnium 88.90585(2) lutetium 50 Sn Sb 74.92160(2) antimony 34 32.065(5) selenium 2.1 87.62(1) barium 49 In 48 47 46 43 42 41 45 1.7 44 Ru Rh Pd Ag Cd Nb Mo Tc 40 Zr 39 Y 72.64(1) tin Cu Zn Ga Ge As 33 30.973761(2) arsenic S 16 15.9994(3) sulfur O 8 oxygen 16 7A 2.5 85.4678(3) caesium 38 Sr 69.723(1) indium 65.38(2) cadmium Ni 58.6934(4) palladium Co 58.933200(9) rhodium 1.6 55.845(2) ruthenium 1.8 51.9961(6) 54.938049(9) molybdenum technetium Cr Mn Fe 63.546(3) silver V 50.9415(1) niobium Ti 47.867(1) zirconium Sc 44.955910(8) yttrium 32 28.0855(3) germanium 2.0 Rb 1.0 Ca 31 30 29 28 27 26 25 24 23 22 21 P 15 14.0067(7) phosphorus N 7 nitrogen 15 2.4 40.078(4) strontium 26.981538(2) gallium zinc copper nickel cobalt iron manganese chromium vanadium titanium scandium Si 14 12.0107(8) silicon C 6 carbon 14 6A 2.8 39.0983(1) rubidium 1.5 Al 13 10.811(7) aluminium B 5 boron 13 1.8 20 12 2.1 24.3050(6) calcium 11 5A 2.5 19 10 4A 3.0 22.989770(2) potassium EN 12 9 2.0 Na Mg symbol 8 3A 2.5 2003 atomic weight (mean relative mass) 7 8B http://www.webelements.com/ 7B 1B 2B 3.0 9.012182(3) magnesium atomic number element name 6 5 4 3 Key: 6B 5B 4B 3B 3.5 11 1.5 Be 4 beryllium 2 2A 4.0 6.941(2) sodium Li 3 1.00794(7) lithium H 1 hydrogen 1 1A Periodic Table of theon Elements the world-wide web table the periodic WebElements: Chem 150 Fall, 2015