Chem1411 Tets1 Total Points 50 Answer all questions. Pay attention to units and make the conversions where relevant. Section I 1X15 1. Complete the following sentence. A scientific law is A) a tentative explanation for a set of observations that can be tested by further experimentation. B) a statement describing a relationship between phenomena that is always the same under the same conditions. C) a unifying principle that explains a body of facts and relations. D) a model used to visualize the invisible. 2. Which one of the following is an example of a physical property? A) dynamite explodes D) ice floats on top of liquid water B) meat rots if it is not refrigerated E) a silver platter tarnishes C) gasoline burns 3. Complete the following chart, in order from left to right Isotope Mass Number Protons 40 19 A) 40 Zr, 21 B) 19 K, 40 C) 21 K, 19 D) 40 K, 21 E) Neutrons Electrons 19 38 Sr, 19 4. Convert 4.89 mm to µm. A) 4.89 x 10-6 µm B) 4.89 x 10-3 µm C) 4.89 x 103 µm D) E) 4.89 x 106 µm 4.89 x 109 µm 5. Name the compound CrO3. A) chromium oxide B) chromium(II) oxide C) chromium(III) trioxide D) E) chromium(III) oxide chromium(VI) oxide 6. There are two stable isotopes of chlorine: chlorine-35, with a mass of 34.968853 amu; and chlorine-37, with a mass of 36.965903. Given that the average atomic mass of a chlorine atom is 35.45 amu, which of the following statements is true? 35 Cl with very little 37 A) Chlorine contains almost exclusively 17 17 Cl. 35 17 Chlorine contains more C) Chlorine contains roughly equal amounts of 37 17 Cl than 37 17 B) Cl. 35 17 Cl and 37 17 Cl. 35 17 D) Chlorine contains more Cl than Cl. E) Chlorine contains almost exclusively of 37 17 35 Cl, with very little 17 Cl. 7. If 0.274 moles of a substance weighs 62.5 g, what is the molar mass of the substance, in units of g/mol? A) 2.28 × 102 g/mol D) 2.17 × 102 g/mol 1 B) 1.71 × 10 g/mol E) 6.02 x 1023 g/mol –3 C) 4.38 × 10 g/mol 8. How many moles of C are in 1.22 moles of C6H12O6? A) 7.32 moles C D) B) 87.9 moles C E) C) 1.22 moles C 14.7 moles C 2.44 moles C 9 What is the coefficient for O2 when the following combustion reaction of a fatty acid is properly balanced? __ C18H36O2 + __ O2 __ CO2 + __ H2O A) 1 B) 8 C) 9 D) 26 E) 27 10. Aluminum metal reacts with nitric acid to produce aluminum nitrate and hydrogen gas. Identify the balanced reaction that describes this process. A) Al + HNO3 AlNO3 + H2 D) Al + 3HNO3 Al(NO3)3 + H2 B) Al + HNO3 AlNO3 + H E) 2Al + 6HNO3 2Al(NO3)3 + 3H2 C) Al + 2HNO3 Al(NO3)2 + H2 11. When J. J. Thomson discovered the electron, what physical property of the electron did he measure? A) its charge, e D) its mass, m B) its charge-to-mass ratio, e/m E) its atomic number, Z C) its temperature, T 12. An anion is defined as A) a charged atom or group of atoms with a net negative charge. B) a stable atom. C) a group of stable atoms. D) an atom or group of atoms with a net positive charge. 13. What are the two different ions present in the compound NH4NO3? A) NH4-, NO3+ D) NH43+, NO4+ B) NH4 , NO3 E) NH4+, NO3C) N3-, H+, O214. Which is the formula for lead(IV) chloride? A) Pb4Cl B) PbCl2 C) PbCl3 D) PbCl4 E) Pb2Cl4 15. The straight chain hydrocarbon that contains six carbon atoms is A) propane B) butane C) pentane D) hexane E) heptane Section II Answer all questions. Show all calculations where relevant 16. Give the structures of the sulfide ion, sulfate ion, and sulfite ion, in that order? 17. Define the Law of conservation of energy: 1X2 1X3 Use the following to answer questions 18-: 18a. Use the periodic table above to show where the alkali metals are located. 1 18b. Use the periodic table above to show where the halogen elements are located. 1 18c. Name one compound formed by the Alkali group element and a halogen element. What is the nature of this compound, ionic or covalent? Why? 1X3 18d.Define the term molecule. 1 18e. Name 2 of the seven elements that naturally occur as diatomic molecules? 18f. Name 2 elements that naturally occur as liquid? 2 2 19. An archeologist finds a huge monolith in the desert. In order to estimate the weight of this object; he estimates the dimensions of the monolith and removes some chips from the rock with his hammer, collecting the following data: 3 dimensions of the monolith = 1.5 m × 5.2 m × 13 m mass of rock chips = 41.73 g volume of rock chips = 15.2 cm3 Determine the mass of the monolith in pounds, assuming it is of uniform composition. (1 lb = 453.6 g) 20. An investor paid market price for a chunk of gold that he was told was pure. The gold bar had a mass of 440 g, but was slightly irregular so an exact volume could not be calculated. The investor filled a large graduated cylinder with water, immersed the chunk of gold, and observed an increase in the apparent volume of material in the graduated cylinder of 25.0 mL. Pure gold has a density of 19.3 g/cm3. Did the investor get his money's worth? Why or why not? 3 21. A cyclist averages 18.5 miles per hour. How many minutes will it take for him to complete a 125 kilometer race? (1Mile = 1.61Km) 1 A) 252 min B) 652 min C) 420 min D) 1440 min E) 405 min 22. Ferrocene, Fe(C5H5)2(s), can be prepared by reacting 3.0 g of FeCl2(s) with an equal mass of cyclopentadiene, C5H6(l), and an excess of KOH, as shown in the following reaction FeCl2 + 2C5H6 + 2KOH FeC10H10 + 2H2O A. What is the limiting reagent in this procedure? Show how you arrived at your answer. B. Based on your answer to part A, what mass of Fe(C5H5)2 could theoretically be formed? 1 2 C. A student who carried out this reaction obtained 2.7 g of ferrocene. What was the percent yield for this reaction? 2 23a. What is the number of protons produced by H3PO4 ? 1 23b. Show the stepwise dissociation of this acid, making sure that the reactions are balanced and the state of matter is mentioned in each step: 3X1 24. The percent composition by mass of tartaric acid is: 32.01% C, 4.03% H, and 63.96% O. Given that the molecular mass of tartaric acid is 150 amu, determine its molecular formula. 3 25. Consider the reaction below and answer the following questions: 1X2 Cu + AgNO3 Cu(NO3 )2 + Ag A. Balance this reaction. B. How many grams of silver nitrate are necessary to react completely with 7.000 moles of copper? Bonus Question : 10 Carbon and hydrogen form pure organic compounds. The 3 series of compounds formed by these two elements are alkanes, alkenes and alkynes. A.Alkanes: CH4, C2H6, C3H8, C4H10, etc.,… The alkanes are typified by all single bonds between C and C and c and H. B. Alkenes: C2H4, C3H6, C4H8, C5H10, etc.,… The alkenes have one C& C double bond and all other C&C and C&H bonds are single C. Alkynes: C2H2, C3H4, C4H6, C5H8. etc.,… The alkynes have one C&C triple bond and all other C&C and C&H bonds are single. 1.Give the structure of one representative compound of each series: {hint use your knowledge of the valences of C and H) 2.Give the empirical formula for each of the series using the CnHn notation: Carbon also forms cyclic compound and retaining its valency of 4: Predict the structure of C3H6 (Cyclical C backbone, and all single bonds), C6 H12(Cyclical C backbone, and all single bonds) and C6H6 Cyclical C backbone, with alternating single and double bonds between the C atoms and C&H single bonds):