Chemistry 105: General Chemistry I Dr. Gutow and Dr. Matsuno Spring 2004 Page 1

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1 Page 1 1) Name You are to keep this copy of the test. Your name is in case you leave it behind. 2) Use only a #2 pencil on the answer sheet. 3) Before starting the exam fill in your student ID# (not your SS#). Also fill in your name, course number and sign the form. 4) Fill in the test form section (A, B, C or D). 5) Do not begin the exam until you are told to. 6) You will not get your scan sheet back!!! Circle your answers on this exam sheet and then transfer them to the scan sheet when you are satisfied with all your answers. An answer key will be posted on the class web site and in the glass case across from the lab after the exam. 7) If atomic weights are needed use only those from the attached periodic table. 8) No scratch paper is to be used. Use the back of this exam sheet if necessary. 9) There are 40 equally weighted questions on this exam. You have 90 minutes to complete them. 10) If you believe there is more than one correct answer pick only the best answer. Useful Data Constants c = x 10 8 m/s h = 6.63 x Js density of H 2 O = 1.00 g/ml mass of neutron = x10-27 kg mass of proton = x10-27 kg Units 2.54 cm = 1 inch 3.78 L = 1 gal 1 kg = 2.20 lb 1 % = 10,000 ppm 1 hr = 60 min 1 min = 60 seconds 1 amu = x kg Equations υ = c/λ Δ E = Ε f Ε i E n (hydrogen)= -Rhc/n 2 = (-2.18 x J)/n 2 1/λ = (1.097x10-2 nm -1 )(1/n 2 f - 1/n 2 i ) Δ E = (-2.18x10-18 J)(1/n 2 f - 1/n 2 i ) E photon = hυ = hc/λ E=mc 2, E =(Δ m) c 2 1 % = fraction * 100 % T (in Kelvin) = T (in C) T (in Celsius) = (5/9) (T (in F) -32) A t /A 0 = 0.5 N were N= t / t 1/2 n : principle quantum number l = n-1 : angular momentum quantum number m l = -l l :magnetic quantum number m s = +1/2 or -1/2 : spin quantum number

2 Page 2 Question 1. Pure water is classified as. a. element b. homogeneous mixture c. heterogeneous mixture d. compound e. flavored aquafina 2. Which of the following is a heterogeneous mixture? a. filtered air in a bottle b. grape Kool Aid c. Fox river water d. brass e. none of the above 3. Indicate which of the following wavelengths (λ) or frequencies (ν) has the lowest energy photons. a.those from a radio station with ν = MHz b.those from an X-Ray source with λ = 100 pm c. those from the laser in a CD player with λ = 650 nm d.those from a microwave oven, with ν = 6.0x10 10 Hz e. they are all equal 4. The diameter of the sun is km. In scientific notation this is a x 10 6 km b x10-3 km c x 10 6 km d x 10 3 km e x 10-6 km 5. In one second, light can travel x 10 8 m. How many inches does light travel in one femtosecond (1 fsec = sec)? Useful information (1 in = 2.54cm) a. 118 im b in c in d x 10-5 in e x 10-6 in 6. Which of the following is the correct symbol for a neutron? a. 0 n b. 1 n c. 1 n 1 d. 1 n e. none of the above

3 Page 3 7. Which of the following is the correct symbol for a proton? 0 a. 1 p b. 1 0 p c. 1 1 p d. 0 1 p e. symbol should be just p 8. The first step in the disintegration step of uranium-238 is a formation of thorium-234 ( which is 234 Th). What type of particle does uranium-238 lose? (HINT: you must locate atomic numbers of each atom from the periodic table). a. alpha particle b. electron c. proton d. neutron e. neutrino 9. How many significant digits are present in ? a. 13 b. 12 c. 6 d. 5 e Liquid nitrogen boils at 77 K. What is this temperature in ºF? a ºF b ºF c ºF d. -77 ºF e. 88 ºF 11. An unknown element is found to contain isotopes with the following masses and natural abundances: amu (93.08%), amu (0.42%), amu (6.50%). Identify the element from the list given below. a. S. b. Cl c. Ar d. K e. Ca 12. Why does the noise of a race cars engine have a higher pitch just before it passes you, and a lower pitch as it moves away from you? a. The Doppler effect shifts the frequencies lower as it approaches and higher as it recedes. b. The Doppler effect red-shifts all frequencies (makes them lower). c. The Doppler effect shifts all frequencies to the blue (makes them higher) d. The Doppler effect shifts the frequencies higher as it approaches, and lower as it recedes. e. The Doppler effect shifts the speed higher as it approaches, and lower as it recedes.

4 Page What other subatomic particle is formed in the fusion of two protons to form deuterium? a. proton b. neutron c. electron d. positron e. quark 14. Cobalt-60 is used as a radioactive source approved by the FDA for irradiation of food. This process kills microbes and insects and can delay ripening. What decay pathway is likely for cobalt-60? Table of Band of Stability is attached in the back. a. alpha emission b. beta emission c. positron emission d. neutron emission e. gamma emission 15. Which of the following types of radiation consists of high-energy particles with a negative charge? a. alpha b. beta c. gamma d. neutron emission e. negatron 16. In a nuclear chain reaction, which particle is transferred from one atom to another? a. proton b. neutron c. positron d. beta particle e. uranium 17. Half-life is best described as a. the life that a nuclear chemist leads. b. half of the lifetime of an unstable nucleus c. the time for one-half of the unstable nuclei to decay. d. constantly changing life. e. E=mc Radon-222 has a half-life of 3.8 days. If a balloon is filled with air that has a radioactivity level due to 222 Rn of 12 pci, what will be the radioactivity level due to 222 Rn after 5.4 days? Assume that corrections for background radiation and daughter isotopes have been accounted for. a. 1.4pCi b. 3.2pCi c. 4.5pCi d. 6.0pCi e. 32pCi

5 Page The half-life of the 14 C isotope is 5730 years and our ability to measure 14 C/ 12 C has a limit of 0.1% precision. Will this technique be suitable for samples that are 500,000 years old? Choose the one that best describes the answer and the reason. a. No, because the amount of 14 N should be used for the sample older than 10,000 years. b. Yes, as the isotope decays the rate of loss slows down, so there will always be some of the 14C left in the sample. c. No, 14 C lasts only 11,460 years. d. Yes, 14 C is replenished by neutron bombardment from cosmic radiation, so the sample will always contain 14 C. e No, too much of the isotope will have been lost to be measurable. 20. The most abundant element in the universe is a. iron b. helium c. hydrogen d. nitrogen e. oxygen 21. In 1913 an element was known to "emanate" from radium-226 by alpha emission and then to decay to polonium-218, also by alpha emission. What was the unknown element? a. Radon-224 b. Lead-214 c. Plutonium-238 d. Radon-222 e. Lead An Internet site made the following claim: "The Nuclear Regulatory Commission (NRC) and the Department of Energy (DOE) have recycled millions of pounds of low-level radioactive material into the commercial marketplace. Recently, new evidence has surfaced that suggests that gold from dismantled nuclear warheads, some of it highly radioactive, has made its way into the jewelry industry over the last 50 years. Gold jewelry, if made from this contaminated material, could give the wearer twice as much radiation in one hour as most people get in a year." What simple test could a person carry out to find out if a piece of jewelry contained radioactive contamination? a. Feel it to see if it generates heat. b. See if it glows in the dark. c. Expose some photographic film to it in the dark to see if it fogs the film. d. Wear it and see if you get radiation burns. e. Taste it. It would be mildly sweet if radio activity is present.

6 Page A "critical mass" of uranium-235 is a. the bulk mass of the isotope necessary to sustain a nuclear chain reaction. b. the atomic mass of this, the lightest radioactive isotope. c. the crowd at a Springfield "Isotopes" game. d. the atomic mass of this (or any other) isotope necessary for it to become radioactive e. the atomic mass that uranium-235 can exist as uranium-235 atoms. 24. Nuclear fission produces energy a. because it produces neutrons b. because the total mass of the product isotopes is less than the reactants c. because the total mass of the product isotopes is more than the reactants d. because it is a very powerful chemical reaction. e. because it is a very powerful chain reaction. 25. Creation of isotopes with greater mass numbers than 56 from iron-56 a. was not possible until American scientists created particle accelerators. b. releases energy from nuclear fission. c. is not possible. d. requires a net input of energy. e. none of the above 26. A level of 47 microcuries of radiation was measured. If 1 Curie is equal to 3.70 x becquerels (Bqs), how many Bqs of radiation is that? a.7.9 x10 2 Bq b. 7.9 x 10 8 Bq c. 1.7 x Bq d. 1.7 x 10 6 Bq e 2.26 x10 27 Bqs 27. Calculate the total nuclear binding energy (not per nucleon) of 32 16S in Joules. The mass of the sulfur nucleus in amu is : amu. a x J b x 10 9 J c x J d x 10-9 J e x J

7 Page At absolute zero temperature (at 0 Kelvin), molecules. a. have maximum kinetic energy b. are moving fast c. have zero kinetic energy d. undergo neutron capture process e. undergo alpha emission process Question from here on are for Chapter Line spectra of free atoms and their corresponding ions are due to the changes in the energy of a. protons b. neutrons c. nuclei d. electrons e. molecules 30. Which of the following occur only in discrete (quantized) increments? a. the speed a car drives on the interstate b. the altitude that an airplane flies c. the score in a volleyball game d. the rate at which a sink full of water drains e. the distance a baseball goes from a home base 31. Determine the energy of the photon absorbed or emitted in the hydrogen atom spectrum corresponding to the n i = 3 to n f = 4 transition. a x J b x J c J d x x J e. none of the above 32. In quantum mechanics, an atomic orbital represents a. the space occupied by an electron. b. the space occupied by the nucleus. c. the most probable location of an electron. d. the most probable location of the nucleus. e. degeneracy among s, p, d, and f orbitals

8 Page Which of the following quantum numbers (l and m l ) are for the orbital with the highest energy in the n = 3 shell? a. l = 0, m l = 0 b. l = 3, m l = 3 c. l = 2, m l = 2 d. l = 1, m l = 1 e. l = 4 m l = Which of the following is the shape of s-orbital? a. b. c. d. e. all represent s-orbital 35. Predict the charge of a stable calcium ion. a. +1 b. +2 c. -1 d. -2 e Which element listed below has the ground-state electron configuration 1s 2 2s 2 2p 6 3s 2 3p 4? a. Al b. Cl c. S d. P e. O 37. Which of the following is the ground-state electron configuration of the Mg 2+ ion? a. 1s 2 2s 2 2p 6 3s 2 b. [Ne]3s 2 c. 1s2 2s 2 2p 2 d. [Ne]3s 2 3p 2 e. [He]2s 2 2p 6

9 Page Which of the following is the ground-state electron configuration of the Cu? Hint: check for all the orbitals in each configuration. a. 1s2 2s 2 2p 6 3s 2 4s 1 3d 10 b. 1s2 2s 2 2p 6 3s 2 4s 2 3d 9 c. 1s2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 9 d. 1s2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 10 e. 1s2 2s 2 2p 6 3s 2 3p 6 4s 2 3d Pauli exclusion principle says: a. no two electrons can have the same quantum numbers. b. electrons have both particle- and wave- like properties c. Δx Δ(mv) > h d. if the planck s constant is large, we all appear fuzzy on edges. e. energies are quantized. 40. Which of the following elements would you expect to have the greatest first ionization energy? a. C b. O c. Li d. Be e. the all have the same ionization energy.

10 Page 10 BAND (BELT) OF STABILITY

Radioactivity and Balancing Nuclear Reactions: Balancing Nuclear Reactions and Understanding which Particles are Involves

General Chemistry II Jasperse Nuclear Chemistry. Extra Practice Problems Radioactivity and Balancing Nuclear Reactions: Balancing Nuclear Reactions and Understanding which Particles are Involved he Stability