Part 1 Short Response 1 An atom has 13 electrons an atomic mass of 32 amu and a charge of 3 What is this atom s symbol and how many neutrons does it have 2 Write the electron configuration for the following 3 What is the maximum number of electrons that can have the following a S b Cu c Pb quantum numbers a n 5 b n 4 l 0 c n 3 ml 0 d n 3 l 3 ml 1 ms 1 2 4 Explain why the second ionization energy of potassium is greater than the second ionization energy of calcium 5 Between sodium and fluorine which has a larger atomic radius Explain why this is true based on your knowledge of periodic trends 6 Determine the percent composition and oxidation state of each element in the following a H2SO3 b KMnO4 c Na2Cr2O7 7 Suppose that a system experiences a negative change in internal energy under constant pressure Given that the work required for this process is positive would you expect this process to be exothermic or endothermic Part 2a Extended Response Calculations 1 Consider the combustion of ethane a Write the balanced chemical reaction for the combustion of ethane C2H6 b If 12 3 grams of ethane reacts with 45 6 grams of oxygen gas what mass of water will be collected c If the carbon dioxide produced is collected at a pressure of 1 02 atm and a temperature of 298K what volume will it occupy d Calculate the ratio of the rates of effusion for carbon dioxide and oxygen gas 2 A 5 63 gram sample of an unknown compound containing carbon hydrogen oxygen was burned to produce 8 26 grams of carbon dioxide and 3 39 grams of water a How many moles of each element were in the original 5 63 gram sample b What is the empirical formula of the unknown compound c If the molecular weight of the compound is approximately 120 g mol what is the molecular formula of the compound 3 250 grams of lead II nitrate is added to 100 mL of water It is then added to 250 mL of 0 75M sodium iodide solution a What is the molarity mol L of the original lead II nitrate solution b A precipitation reaction occurs Identify the precipitate and the spectators in this reaction c Write the balanced net ionic equation for this reaction d How many moles of the precipitate are formed e What is the molarity of the nitrate ion after the two solutions are added together 4 A laser produces photons with a wavelength of 685 nm and is used to melt and heat a 250 gram sample of distilled water a What is the energy of each photon produced by the laser b How much heat must be added to completely melt the ice from the freezing point and heat it to 76 C c How many moles of photons are required to produce this amount of heat d If the bond enthalpy of the H O bond in water is 467 kJ mol would you expect the laser to decompose any of the water into its elements Part 2b Extended Response Lewis Structures Dipole Moments and Bond Enthalpy 1 For the following draw the Lewis dot structure indicate the electron domain and molecular geometry identify the hybridization of the central atom and state whether or not you would expect the molecule to experience a dipole moment Be sure to include any resonance structures if there are any a NH3 b CO3 2 c SCO d XeF4 2 Sulfur trioxide SO3 is a molecule that has 3 resonance structures in which there is one S O double bond and two S O single bonds Two additional structures can be drawn the first has two S O double bonds and the other has three S O double bonds None of the structures have lone pairs a Based on your knowledge of formal charge which structure would be the most stable b What would the molecular geometry of this structure be c Would you expect this structure to experience a dipole moment 3 Answer the following questions based on the attached diagram of propiolic acid a How many sigma and pi bonds are in this structure b What is the molecular geometry of C2 c What is the hybridization of C1 4 If the length of an Na Cl bond is 8 95 Angstrom and of an electron is transferred calculate the dipole moment 5 Which of the following would you expect to require the greatest amount of energy to break the N N bond Justify your answer with your knowledge of Lewis structures and bond enthalpies a N2H4 b N2H2 c N2 6 For the following indicate the total number of nodes and how many of them are angular nodes a 4d b 3p
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