Physiological Chemistry I Exam II Dr. Melissa Kelley October 14, 2003

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1 Physiological hemistry I Exam II Dr. Melissa Kelley October 14, 2003 Name Please write your name on the back also. You have 75 minutes to complete this exam. Provide the one best answer for each, following the instructions given in each section of the exam. Multiple hoice: Select the one best answer for each question. Multiple answers will not be accepted. Each question is worth 2 points. 1. Which one of the following is not true about elements that form cations? A. The atoms lose electrons in forming ions. B. The elements are metals.. They are located to the left of the periodic table. D. They have low ionization energies. E. They have high electron affinities. 2. Which of the following statements is not true? A. hemical bonding involves interactions only through valence electrons. B. Ionic bonds are formed between an element that has a low ionization energy and an element that has a high ionization energy.. ovalent compounds are held together by electrostatic forces. D. Polar covalent bonds can involve unequal sharing of electrons. 3. Assuming reactions between the following pairs of elements, which pair is most likely to form an ionic compound? A. chlorine and oxygen B. cesium and iodine. carbon and chlorine D. fluorine and iodine 4. Assuming reactions between the following pairs of elements, which pair is most likely to form a covalent compound? A. lithium and iodine B. potassium and chlorine. calcium and chlorine D. carbon and oxygen 5. Which of the following statements is not true? A. Triple bonds are generally more stable than single bonds. B. The bond energy is greatest for a single bond.. Bond length is greatest in a single bond. D. Double bonds are generally more stable than single bonds. 1

2 6. Which of the following statements is not true? A. In determining properties such as solubility, melting point and boiling point, intramolecular forces are more important than intermolecular forces. B. The existence of resonance makes a molecule more stable than would otherwise be the case.. ovalent compounds tend to have lower melting and boiling points than ionic compounds. D. Resonance occurs when two or more different, valid Lewis structures can be drawn for a molecule. 7. (7 points) Name the following: a. FeSO 4 b. Pl 5 c. AlBr 3 d. KlO e. N 4 l f. u 2 O g. BaO 3 8. (7 points) Write the formula for each of the following compounds: a. Potassium permanganate b. Silver chromate c. ydrogen peroxide d. alcium hydroxide e. Lithium Sulfite f. Sodium chlorate g. Ammonium Nitrate 9. (4 points) Which of the following compounds would be predicted to have a higher boiling point? Briefly explain your reasoning. Ethane Ethanol O 2

3 Draw the Lewis Structures for each of the following compounds and assign the VSEPR geometry of the following molecules. Each structure is worth 5 points N 2. VSEPR geometry S. VSEPR geometry For the following questions only draw the Lewis Structures. VSEPR geometry is not required OO F 3 2 l 3

4 15. (18 points) Balance the following chemical equations: All coefficients including the number one must be shown in the blank provided to receive maximum credit. ANY BLANK NOT FILLED IN WILL BE MARKED WRONG a. a(s) + l(g) al 2 (s) + 2 (g) b. Mg(O) 2 (s) + l(g) Mgl 2 (s) + 2 O(l) c (l) + O 2 (g) O 2 (g) + 2 O(l) Perform the following calculations: redit will only be given if you show your work and units. 16. (4 points) ow many grams of sulfur are present in 1.55 x atoms of sulfur? [Atomic weight: S, g/mol]. Your answer should contain the correct number of significant figures. 4

5 17. (5 points) Glucose ( 6 12 O 6 ) is an important energy-rich compound, produced by photosynthesis: O 2 (g) + 2 O(l) 6 12 O 6 (l) + O 2 (g) What mass of glucose, in grams, can be produced from 2.61 mol of O 2? Your answer should contain a balanced chemical equation. Your answer should also contain the correct number of significant figures. Molar mass of glucose = g/mol Molar mass of O 2 = 44.0 g/mol Molar mass of O 2 = 32.0 g/mol Molar mass of 2 O = 18.0 g/mol 18. (4 points) ow many atoms are there in one ounce (28.4 g) of pure gold? [Atomic weight: Au, g/mol]. Your answer should contain the correct number of significant figures. 19. (4 points) Dinitrogen monoxide or laughing gas (N 2 O) is used as a dental anesthetic and as an aerosol propellant. ow many moles of N 2 O are present in 12.6 g of the compound? [Atomic weights: N, g/mol, O, g/mol]. Your answer should contain the correct number of significant figures. 5

6 20. (10 points) While at Wal-Mart, you decide to fill your car with 10 gallons of gasoline (octane ). Your car engine performs the following chemical reaction known as combustion: 8 18 (l) + O 2 (g) O 2 (g) + 2 O(l) ow many liters of water are created from the combustion of 10 gallons of gasoline? Your answer should contain a balanced chemical equation. Your answer should also contain the correct number of significant figures. Useful information: Density of gasoline= 0.69 g/ml Density of water = 0.99 g/ml 1 gallon = 3.78 liters Molar mass of 8 18 = g/mol Molar mass of O 2 = 32.0 g/mol Molar mass of O 2 = 44.0 g/mol Molar mass of 2 O= 18.0 g/mol 6

e. As a transition metal, cannot be determined from the information given

e. As a transition metal, cannot be determined from the information given hemistry 121 Exam 2 Practice Winter 2018 The following practice examination contains 31 questions. Tuesday s exam will contain 32 questions valued at 3.5 points/question and some rather tasty opportunities