CHEM 231 Final Exam Review Challenge Program

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1 CHEM 231 Final Exam Review Challenge Program Directions: Read these!! Conversions: 1 ml = 1 cm 3 1 gallon=3.785 Liter 1 pound(lb) = 454 g 760 torr = 1 atm T(in K) = T(in C) Avagadro s number: /mol Plank s constant: h= J s Kinetic energy of a particle Ek = (1/2)mv 2 Ideal gas Law: PV=nRT Gas constant: R = (L atm/k mol) Speed of light: c= m/s (m is mass; v is velocity) Thermodynamics: E = internal energy q = heat w = work E = q+w H = enthalpy H = q (under conditions of constant pressure and no work other than expansion work) The relation between heat(q), specific heat (s) and temperature change: q = m s T Specific heat of water = J/(g C) EM radiation = wavelength = frequency =c Ephoton=h or Ephoton=hc/ where hc= J m H atom energies n = quantum number; 1, 2, 3, 4, E = -(RHhc)/n 2 Rydberg constant: RH = m; (RHhc) = J The following terms are commonly used to describe molecular and electron domain geometries: Linear Bent Trigonal planar Pyramidal T-shaped Tetrahedral See-saw Square planar Trigonal bipyramidal Square pyramidal Octahedral You will need to know the following information: The following are strong acids. All other acids appearing on this exam are weak. HNO3, H2SO4, HCl, HBr, HI 1. Gold has a density of g/cm 3. Calculate the mass in grams and in pounds in a sheet of gold plating with dimensions cm x cm and thickness m. 2. Ethanol has a density of g/cm 3. Calculate its density in the units of lb/gallon. 3. Fill in the blanks in the following table. Each row corresponds to an isotope of a neutral atom. It may, or may not, be the most common isotope. The first row is completed as an example.

2 Name of element Number of electrons Number of protons Number of neutrons Mass number Lithium Nitrogen Carbon Isotope symbol or 7 3 Li 13 C 7 Li 4. Answer the following multiple choice questions by circling the letter corresponding to correct answer. (i) Air is (a) a heterogeneous mixture (b) a homogeneous mixture (c) a pure compound (d) an element (ii) Methane is (a) a molecular compound (c) a mixture (iii) Water is (a) a heterogeneous mixture (c) a pure compound (iv) Carbon dioxide is (a) a heterogeneous mixture (c) an ionic compound (b) an ionic compound (d) an element (b) a homogeneous mixture (d) an element (b) a homogeneous mixture (d) a molecular compound (v) Millikan s oil-drop experiment found (a) matter is made of atoms (b) electrical charges are multiples of a fundamental unit of charge (c) cathode rays are made of small negatively charged particles (d) atoms have small positively-charged nuclei 5. What is an electrolyte? Your answer should describe how can an electrolyte can be detected experimentally and should also state what is present in solution that makes a substance an electrolyte. 6. Write balanced chemical equations representing the reactions described below. (a) The precipitation of solid magnesium carbonate from solutions of magnesium bromide and sodium carbonate. Write a full molecular equation. (b) The neutralization of aqueous nitric acid by aqueous potassium hydroxide. Write full molecular equation. (c) The oxidation of zinc by a strong acid. Zinc ions have a +2 charge. Write a net ionic equation. (d) The oxidation of copper metal to copper(ii) ion by silver ion (charge = +1). Write a net ionic equation. (e) The STANDARD combustion of propane (C3H8).

3 (f) The reaction of solid sodium hydrogen carbonate with aqueous acetic acid (C2H3O2H, a weak acid). Carbon dioxide and aqueous sodium acetate (NaC2H3O2) are products and there is one other product. Write a full molecular equation. 7.. Fill in the following table of names and formulas of ionic compounds. If the name is given, fill in the formula; if the formula is given, fill in the name. Name Formula Iron(III) sulfide or ferric sulfide Copper(I) carbonate or cuprous carbonate Calcium nitrite Ammonium nitrate Zinc iodide Siver nitrate Sodium hydrogen carbonate or sodium bicarbonate Na2CO3 MgCl2 CuO 8. Calculate the mass of solid sodium hydrogen carbonate required to neutralize ml of 12.00M HCl in the following reaction: NaHCO3(s) + HCl(aq) NaCl(aq) + H2O(l) + CO2(g) The formula weights of the components of this reaction are as follows. Sodium hydrogen carbonate:84.007g/mol. Hydrochloric acid: g/mol. Sodium chloride: g/mol. Water: g/mol. Carbon dioxide: g/mol. 9. The reaction representing the fermentation of glucose to make ethanol and carbon dioxide is C6H12O6(aq) 2C2H6O(aq) + 2CO2(g). Calculate the mass of carbon dioxide resulting from the fermentation of 100.0g of glucose. The molecular weights of the components of this reaction are as follows. Glucose:180.16g/mol. Ethanol: g/mol. Carbon dioxide: g/mol. 10. Using the specific heat in the data section, calculate the energy required to raise the temperature of 1000 grams of water from 20 C to 50 C. (a) J (b) kj (c) kj (d) J 11. The bond enthalpy for one C-H bond in CH4 is 412 kj/mol. What is the enthalpy change for forming one mole of methane molecules from one mole of carbon and four moles of hydrogen atoms? (a) +412 kj (b) -412 kj (c) kj (d) kj

4 12. What is the standard enthalpy change for the combustion of acetylene, C2H2? (You will first need to write the standard combustion reaction for acetylene.) (a) kj/mol (b) kj/mol (c) +226 kj (d) kj 13. From the answer to question 1, calculate the amount of energy available from burning grams of acetylene. (a) kj (b) kj (c) kj (d) 2256 kj 14. The energy required to break a particular chemical bond is reported to be 425 kj/mole. What wavelength of electromagnetic radiation corresponds to photons with just enough energy required to break this bond? (a) 281 m (b) 2.81 m (c) 281 nm (d) mm 15. What is the kinetic energy of one nitrogen molecule (N2) moving at a speed of 450 m/s? (a) 2835 kj (b) 2835 J (c) J (d) J 16. What is the energy is of the 2s state of hydrogen? (a) J (b) J (c) J (d) J 17. Radiation with wavelength 15 m can induce which of the following processes? (b) Causing bonds to vibrate. (b) Breaking chemical bonds. (c) Removing inner electrons. (d) Removing outer electrons. 18. An electron has the quantum numbers: n=2; l=1; ml =-1; ms=1/2. What is the subshell designation of this electron? (a) 2p (b) 1d (c) 2s (d) This is an impossible set of quantum numbers 19. Which is greater? (a) Enthalpy of 1.00L of water at 25 C (b) Enthalpy of 1.00L of water at 30 C 20. Which is greater? (a) Enthalpy of 1 mole of methane and 2 moles of oxygen gas at 25 C (b) Enthalpy of 1 mole of carbon dioxide and 2 moles of liquid water at 25 C 21. Which is greater? (a) The energy required to break a typical chemical bond (b) The energy of an infrared photon 22. Which is greater? (a) Enthalpy of 2 moles of H atoms (b) Enthalpy of 1 mole of H2 molecules 23. Which is greater? (a) Wavelength of a particle with energy J (b) Wavelength of a particle with energy J 24. Calculate the enthalpy change of the reaction P4 O6 s 2O2 g P4 O10 s P4 s 3O2 g P4 O6 s H kJ thermochemical equations: P s 5O g P O s H kJ from the following pair of.

5 25. Write complete (or condensed) electron configurations for each of the following elements. Follow the pattern of the example: Example: C: 1s 2 2s 2 2p 2 or [He] 2s 2 2p 2 (a) Mg (b) Br (c) Ag (d) S (e) Cu Indicate in which region of the spectrum each of the following photons lies. (a) =1cm (b) =15 m (c) =0.01nm (d) =500nm 27. Report your answer to the nearest 1 kj with the correct sign. O-H bond enthalpy: 464 kj/mol O=O bond enthalpy: 498 kj/mol H-H bond enthalpy: 436 kj/mol 28. Within each pair, circle the letter corresponding to whichever quantity is greater. (i) (a) Radius of a potassium atom (b) Radius of a bromine atom (ii) (a) Ionization energy of sulfur (iii)(a) Ionization energy of helium (b) Ionization energy of magnesium (b) Ionization energy of chlorine (iv) (a) Energy required to remove a 2s electron from fluorine (b) Energy required to remove 2s electron from chlorine (v) (a) Energy required to remove one electron from the F- ion (b) Energy required to remove one electron from the O- ion (vi)(a) Polarity of the bond in HF (vi)(a) Radius of H- ion (viii)(a) Ionization energy of hydrogen (ix)(a) Bond enthalpy of a C-C (single) bond (b) Polarity of the bond in HCl (b) Radius of He atom (b) Ionization energy of sodium (b) Bond enthalpy of a C=C (double) bond 29. A particular bond vibration in a molecule is induced by absorption of photons with wavelength 15 m. What is the energy of one of these photons? 30. For the reaction N2(g) + 2O2(g) 2NO2(g), calculate the mass of nitrogen dioxide made from 1.000g of nitrogen and 1.000g of oxygen. (There may be a limiting reactant.) 31. Multiple choice questions (i) SO3 is (ii) ZnO is (a) acidic. (a) acidic. (b) basic. (b) basic. (c) neither. (c) neither. (iii) The oxidation number of one (iv) The oxidation number of H in NaH is of the O atoms in H2O2 is (a) 0 (a) 0 (b) +2 (b) +1

6 (c) -1 (c) -1 (d) -2 (d) +2 (v) The oxidation number of one of the H atoms in H2 is (a) 0 (b) +1 (c) -1 (d) Write balanced chemical equations representing the following reactions (a) Reaction of magnesium oxide with hydrochloric acid. (Full molecular AND net ionic) (b) Reaction of potassium and water; one of the products is hydrogen. 33. Give the values of the indicated quantities for each structure pictured. The electronegativities of the atoms in this problem are: H: 2.1 S: 2.5 N: 3.0 O: 3.5 (a) For the molecule pictured above: Formal charge of H (either one) Formal charge of O (either one) Oxidation no. of H (either one) Oxidation no. of O (either one) Is octet rule satisfied for O? Yes No (circle one) Total charge of molecule _ (b) For the molecule pictured above: Formal charge of N Oxidation no. of N _ Is octet rule satisfied for N? Yes No (circle one) Total charge of molecule _

7 33. Draw Lewis structures of the molecules indicated in the boxes provided. Indicate the molecular and domain geometry for all. H 3 O + CO OH - SO 2 CO 2 NH 3