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chem1a-spring04-mt1-unknown2-exam - 1 In the combustion of...

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Unformatted text preview: 1.) In the combustion of butane (C4H10) in excess O2 to give CO2 and H2O, how many moles of CO2 are formed from each mole of butane? A) 1 B) 2 C)3 D)4 E)5 2.) If 1 mole of glucose (C6H12O6) reacts with 1 mole of O2, according to the reaction below, C6 H12O 6 + 6 O2 6 CO2 + 6 H2O which is the limiting reagent in the reaction? A) C6H12O6 B) O2 C) CO2 D) H2O E) none of these 3.) Which of the following compounds exhibit ionic bonding? Mark all that apply. A) Cl2 B) CO2 C) CH4 D) RbCl E) MgBr2 4.) 6.) Which of the following must be the same before and after a chemical reaction? Mark all that apply. A) The total mass. B) The total pressure. C) The total number of molecules. D) The total number of moles. E) The total number of atoms (including those in molecules). 5.) Which of the following contains the most molecules? A) 5.0 g CO2 B) 5.0 g O3 C) 5.0 g H2O D) 5.0 g CO E) 5.0 g Xe 6.) Which difluoropropane (C3H6F2) molecule is chiral? (note: the H atoms are not shown) F C C C A.) F F F B.) C C C F F C C C C. ) F C C C D.) F 7.) 10) Which of the following compounds contains at least one purely covalent bond (≈ 0 % ionic character)? A) CHCl3 B) MnO42- anion C) NaI 8.) The H-N-H angle in ammonia (NH3) is: a) b) c) d) e) < 100° > 120° = 109.5° between 109.5° and 120° between 100° and 109.5° D) HSO2 E)N3- anion 9.) The H-N-H angle in the ammonium cation (NH4+) is: a) b) c) d) e) < 100° > 120° = 109.5° between 109.5° and 120° between 100° and 109.5° 10.) Which of the following is isoelectronic with N2? a) b) c) d) e) NaCl O2 Cl2 CO H2 Short Answer: 1.) Arrange the following in order of decreasing mass: 4.85 x 1022 molecules of BF3 0.5 mole of O2 gas 3.2 grams of H2O ____________________ > ____________________ > ____________________ greatest mass smallest mass 2.) For each molecule indicate the steric # of the central atom, the shape, and the presence or absence of a dipole moment: A. B. C. D. E. F. G. H. Molecule PCl6BeCl2 SiH4 ClO4NO2ClF3 Linear V-shaped/Bent Trigonal Planar Pyramidal Tetrahedral Trigonal Bipyramidal Octahedral T-shaped Workspace Steric # Shape Dipole (Y or N) 3.) A hydrocarbon of molecular weight 26 is burned to yield CO2 and H2O. The mass spectrum of the products is shown below: Intensity 18 44 m/e A. Write a balanced equation for the reaction. B. Draw the Lewis Electron Dot Structure for the hydrocarbon. C. Use VSEPR to determine the shape of the molecule. In this molecule, what is the largest number of atoms in a single plane? 4.) A naturally abundant sample of an element is analyzed in a mass spectrometer, yielding the following spectrum: Intensity 10 1 20 22 m/e A. For each peak, what are the Atomic Number, the number of protons and the number of neutrons. B. What is the atomic weight of the naturally abundant element? C. What is the element? 5.) Consider three beams of light (A, B, C) with equal intensity but the different wavelengths shown here: A) 800 nm B) 500 nm C) 300 nm A. Which beam(s) will eject an electron from the metal whose profile is shown below. B. Which beam(s) will eject electrons with the greatest kinetic energy? Explain in 20 words or less. C Which beam(s) eject the greatest number of electrons from the metal? Explain in 20 words or less. ...
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