课程名称︰普通化学丙 课程性质︰必修 课程教师︰黄信炅 开课系所︰物治、农艺 考试日期（年月日）︰2010/11/12 考试时限（分钟）：10:20－13:10 (170 分钟) 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : General Chemistry C Midterm Exam. 1.Naming the following compounds. (10 pts) (a) Al(NO3)3 (b) FeSO3 (c) MnCl2 (d) CsClO (e) KBrO4 (f) PCl3 (g) N2O5 (h) H2S (i) NaClO3 (j) O2F2 2.Write formula for following compounds. (10 pts) (a) beryllium hydride (b) gallium oxide (c) nitric acid (d) chromium(III) sulfide (e) sodium dichromate (f) ammonium sulfite (g) mercury(I) chlorite (h) lead(IV) sulfide (i) potassium cyanide (j) copper(I) chloride 3.DDT, an insecticide harmful to fish, birds and humans, is produced by the following reaction: ( Cl:35.45 O:16.00 C:12.01 H:1.008 ) 2 C6H5Cl + C2HOCl3 → C14H9Cl5 + H2O Chlorobenzene chloral DDT In a government lab, 1142 g of chlorobenzene is reacted with 485 g of chloral. a.What mass of DDT is formed? (2 pts) b.Which reactant is limiting? Which is in excess? (2 pts) c.What mass of the excess reactant is left over? (2 pts) d.If the actural yield of DDT is 200.0 g, what is the percent yield? (2 pts) 4.Give the balanced equation for each of the following chemical reactions. (a)KO2(s) + H2O(l) → KOH(aq) + O2 (g) + H2O2(aq) (2 pts) (b)Combustion of 47.6 mg cumene produces some CO2 and 42.8 mg water. The molar mass of cumene is between 115 and 125 g/mol and cumene is a compound containing only carbon and hydrogen. (4 pts) (C:12.01 H:1.008) (c)O2(g) + H2O(l) + Pb(s) → Pb(OH)2(s) (2 pts) 5.An ionic compound MX3 is prepared according to the following unbalanced chemical equation. M + X2 → MX3 A 0.105-g sample of X2 contains 8.92 × 1020 molecules. The compound MX3 consists of 54.47% X by mass. What are the atomic masses for M and X, respectively? Starting with 1.00 g each of M and X2, what mass of MX3 can be prepared? (6 pts) (Avogadro’s number: 6.022×1023) 6.A student titrates an unknown amount of potassium hydrogen phthalate (KHP, molar mass = 204.22 g/mol) with 20.46 mL of 0.1000 M NaOH solution. What mass of KHP was titrated by the sodium hydroxide solution? (4 pts) 7.In most of its ionic compounds, cobalt is either Co(II) or Co(III). One such compound, containing chloride ion and waters of hydration was analyzed, and the following results were obtained. A 0.256-g sample of the compound was dissolved in water, and excess silver nitrate was added. The silver chloride was filtered, dried, and weighed, and it had a mass of 0.308 g. A second sample of 0.416 g of the compound was dissolved in water and an excess of sodium hydroxide was added. The hydroxide salt was filtered and heated in a flame, forming cobalt (III) oxide. The mass of cobalt(III) oxide formed was 0.145 g. (Ag:107.9 Cl:35.45 Co:58.93 O:16.00 H:1.008) a.What is the percent composition, by mass, of the compound? (4 pts) b.Assuming the compound contains one cobalt ion per formula unit, what is the formula? (2 pts) c.Write balanced equations for the three reactions described. (6 pts) 8.At elevated temperatures, sodium chlorate decomposes to produce sodium chloride and oxygen gas. A 0.8765-g sample of impure sodium chlorate was heated until the production of oxygen gas ceased. The oxygen gas collected over water occupied 57.2 mL at a temperature of 22 °C and a pressure of 734 torr. Calculate the mass percent of NaClO3 in the original sample. (At 22 °C the vapor pressure of water is 19.8 torr.) (4 pts) (R=0.08206L‧atm/K‧mol ; Na: 22.99 Cl:35.45 O: 16.00) 9.One way of separating oxygen isotopes is by gaseous diffusion of carbon monoxide. The gaseous diffusion process behaves like an effusion process. Calculate the relative rates of effusion of 12C16O, 12C17O, and 12C18O. (4 pts) 10.Ethene is converted to ethane by the reaction C2H4(g) + H2(g) → C2H6(g) C2H4 flows into a catalytic reactor at 25.0 atm and 300. °C with a flow rate of 1000. L/min. Hydrogen at 25.0 atm and 300. °C flows into the reactor at a flow rate of 1500. L/min. If 15.0 kg C2H6 is collected per minute, what is the percent yield of the reaction? (4 pts) (R=0.08206L‧atm/K‧mol ; C: 12.01 H: 1.008) 11.At 25°C, the following heats of reaction are known: ΔH (kJ/mol) 2ClF + O2 → Cl2O + F2O 167.4 2CIF3 + 2O2 → Cl2O + 3F2O 341.4 2F2 + O2 → 2F2O –43.4 At the same temperature, calculate ΔH for the reaction: (4 pts) ClF + F2 → ClF3 12.Given: Cu2O(s) + (1/2)O2(g) → 2CuO(s) ΔH° = –144 kJ Cu2O(s) → Cu(s) + CuO(s) ΔH° = +11 kJ Calculate the standard enthalpy of formation of CuO(s). (4 pts) 13.Which of the following statements is/are true? (3 pts) a.A property that is independent of the pathway is called an intensive property. b.In exothermic reaction, potential energy stored in chemical bonds is being converted to thermal energy via heat. c.The change in enthalpy can always be thought of as equal to energy flow as heat. 14.The wavelength of light associated with the n = 2 to n = 1 electron transition in the hydrogen spectrum is 1.216 × 10–7 m. By what coefficient should this wavelength be multiplied to obtain the wavelength associated with the same electron transition in the Be3+ ion? (2 pts) a.1/9 b.1/7 c.1/4 d.1/3 e.1/16 15.Write the electron configurations for the following elements: (5 pts) a.Ga b.Cu c.Ca d.Br e.Bi 16.The figure below represents part of the emission spectrum for a one-electron ion in the gas phase. All the lines result from electronic transition from excited states to the n = 3 state. (h=6.626×10-34 J‧ s ; c = 2.998×108 m/s) a.What electronic transitions correspond to lines A and B? (2 pts) b.If the wavelength of line B is 142.5 nm, calculate the wavelength of line A. (4 pts) 17.Although no currently known elements contain electrons in g orbitals in the ground state, it is possible that these elements will be found or that electrons in excited states of known elements could be in g orbitals. For g orbitals, the value of l is 4. What is the lowest value of n for which g orbitals could exist? What are the possible values of ml? How many electrons could a set of g orbitals hold? (6 pts) --

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