AP Nuclear and Organic Review Multiple Choice: 1. Types of hybridization exhibited by the C atoms in propene, CH3CHCH2, include which of the following? I. sp II. sp2 III. sp3 (A) I only (B) III only (C) I and II only (D) II and III only (E) I, II, and III 2. O || CH3—C—CH2—CH3 The organic compound represented above is an example of (A) an organic acid (C) an ether (E) a ketone (B) (D) an alcohol an aldehyde 3. If 87.5 percent of a sample of pure I decays in 24 days, what is the half-life of I? (A) 6 days (B) 8 days (C) 12 days (D) 14 days (E) 21 days 131 131 4. The graph above shows the results of a study of the reaction of X with a large excess of Y to yield Z. The concentrations of X and Y were measured over a period of time. According to the results, which of the following can be concluded about the rate law for the reaction under the conditions studied? (A) It is zero order in [X]. (B) It is first order in [X]. (C) It is second order in [X]. (D) It is first order in [Y]. (E) The overall order of the reaction is 2. 5. CH3CH2OH boils at 78oC and CH3OCH3 boils at –24oC, although both compounds have the same composition. This difference in boiling points may be attributed to a difference in (A) molecular mass (B) density (C) specific heat (D) hydrogen bonding (E) heat of combustion 6. X. CH3–CH2–CH2–CH2–CH3 Y. CH3–CH2–CH2–CH2–OH Z. HO–CH2–CH2–CH2–OH Based on concepts of polarity and hydrogen bonding, which of the following sequences correctly lists the compounds above in the order of their increasing solubility in water? (A) Z<Y<X (B) Y<Z<X (C) Y<X<Z (D) X<Z<Y (E) X<Y<Z 7. Which of the following pairs of compounds are isomers? C (A) CH3-CH2-CH2-CH3 and CH3- | H-CH3 CH3 C C (B) CH3- | H–CH3 and CH- | =CH2 CH3 CH3 O || CH3- C -CH3 (C) CH3-O-CH3 and (D) CH3-OH and CH3-CH2-OH (E) CH4 and CH2=CH2 8. The isomerization of cyclopropane to propylene is a first–order process with a half–life of 19 minutes at 500_C. The time it takes for the partial pressure of cyclopropane to decrease from 1.0 atmosphere to 0.125 atmosphere at 500_C is closest to (A) 38 minutes (B) 57 minutes (C) 76 minutes (D) 152 minutes (E) 190 minutes 9. For the types of radiation given, which of the following is the correct order of increasing ability to penetrate a piece of lead? a. Alpha particles < gamma rays < beta particles b. Alpha particles < beta particles < gamma rays c. Beta particles < alpha particles < gamma rays d. Beta particles < gamma rays < alpha particles e. Gamma rays < alpha particles < beta particles 10. The structural isomers C2H5OH and CH3OCH3 would be expected to have the same values for which of the following? (Assume ideal behavior.) a. Gaseous densities at the same temperature and pressure b. Vapor pressures at the same temperature c. Boiling points d. Melting points e. Heats of vaporization 11. 25 1 98 Cf a. b. 12. 131 2 n + 54 Xe + _? What is the missing product in the nuclear reaction represented above? 11 4 42 Mo 11 8 44 Ru c. d. 120 42 Mo 12 0 44 Ru e. 12 2 46 Pd Which of the following does NOT behave as an electrolyte when it is dissolved in water? a. CH3OH c. NH4Br e. Sodium acetate, CH3COONa b. K2CO3 d. HI 13. Which of the following represents a pair of isotopes? Atomic Mass Number Number (A) I. 6 14 II. 7 14 (B) I. 6 7 II. 14 14 (C) I. 6 14 II. 14 28 (D) I. 7 13 II. 7 14 (E) I. 8 10 II. 16 20 214 14. When 84 Po decays, the emission consists consecutively of an particle, then two particles, and finally another particle. The resulting stable nucleus is 206 206 210 (A) 83Bi (B)210 82 Pb (C) 82Pb (D)21083 Bi (E) 81Tl 14 14 15. The radioactive decay of 6C to 7N occurs by the process of (A) beta particle emission (D) electron capture (B) alpha particle emission (E) neutron capture (C) positron emission 16. The alkenes are compounds of carbon and hydrogen with the general formula CnH2n. If 0.561 gram of any alkene is burned in excess oxygen, what number of moles of H2O is formed? (A) 0.0400 mole (C) 0.0800 mole (E) 0.800 mole (B) 0.0600 mole (D) 0.400 mole 17. A 27.0–gram sample of an unknown hydrocarbon was burned in excess oxygen to form 88.0 grams of carbon dioxide and 27.0 grams of water. What is a possible molecular formula of the hydrocarbon? (A) CH4 (C) C4H3 (E) C4H10 (B) C2H2 (D) C4H6 II Free Response: 1997 D Answer each of the following questions regarding radioactivity. (a) Write the nuclear equation for decay of 234 94 Pu by alpha emission. (b) Account for the fact that the total mass of the products of the reaction in part (a) is slightly less than that of the original 234 94 Pu . (c) Describe how , , and rays each behave when they pass through an electric field. Use the diagram below to illustrate your answer. (d) Why is it not possible to eliminate the hazard of nuclear waste by the process of incineration? 2007 part A, form B, question #2 (repeated in the atomic theory section) Answer the following problems about gases. (a) The average atomic mass of naturally occurring neon is 20.18 amu. There are two common isotopes of naturally occurring neon as indicated in the table below. Isotope Mass (amu) Ne-20 19.99 Ne-22 21.99 (i) Using the information above, calculate the percent abundance of each isotope. (ii) Calculate the number of Ne-22 atoms in a 12.55 g sample of naturally occurring neon. (b) A major line in the emission spectrum of neon corresponds to a frequency of 4.341014 s-1. Calculate the wavelength, in nanometers, of light that corresponds to this line. (c) In the upper atmosphere, ozone molecules decompose as they absorb ultraviolet (UV) radiation, as shown by the equation below. Ozone serves to block harmful ultraviolet radiation that comes from the Sun. O3(g) UV O2(g) + O(g) A molecule of O3(g) absorbs a photon with a frequency of 1.001015 s-1. (i) How much energy, in joules, does the O3(g) molecule absorb per photon? (ii) The minimum energy needed to break an oxygen-oxygen bond in ozone is 387 kJ mol-1. Does a photon with a frequency of 1.001015 s-1 have enough energy to break this bond? Support your answer with a calculation. 1998 D Answer each of the following using appropriate chemical principles. (c) Dimethyl ether, H3C-O-CH3, is not very soluble in water. Draw a structural isomer of dimethyl ether that is much more soluble in water and explain the basis of its increased water solubility. In each case, justify your choice. 2002 B Consider the hydrocarbon pentane, C5H12 (molar mass 72.15 g). (a) Write the balanced equation for the combustion of pentane to yield carbon dioxide and water. (b) What volume of dry carbon dioxide, measured at 25˚C and 785 mm Hg, will result from the complete combustion of 2.50 g of pentane? (c) The complete combustion of 5.00 g of pentane releases 243 kJ of heat. On the basis of this information, calculate the value of ∆H for the complete combustion of one mole of pentane. (d) Under identical conditions, a sample of an unknown gas effuses into a vacuum at twice the rate that a sample of pentane gas effuses. Calculate the molar mass of the unknown gas. (e) The structural formula of one isomer of pentane is shown below. Draw the structural formulas for the other two isomers of pentane. Be sure to include all atoms of hydrogen and carbon in your structures. 2003 D (repeated in bonding) Compound Name Compound Formula (kJ mol-1) ∆H˚vap Propane CH3CH2CH3 19.0 Propanone CH3COCH3 32.0 1-propanol CH3CH2CH2OH 47.3 Using the information in the table above, answer the following questions about organic compounds. (a) For propanone, (i) draw the complete structural formula (showing all atoms and bonds); (ii) predict the approximate carbon-to-carbon-to-carbon bond angle. (b) For each pair of compounds below, explain why they do not have the same value for their standard heat of vaporization, ∆H˚vap. (You must include specific information about both compounds in each pair.) (i) Propane and propanone (ii) Propanone and 1-propanol (c) Draw the complete structural formula for an isomer of the molecule you drew in, part (a) (i). (d) Given the structural formula for propyne below, H | H—C—CC—H | H (i) indicate the hybridization of the carbon atom indicated by the arrow in the structure above; (ii) indicate the total number of sigma () bands and the total number of pi (π) bonds in the molecule