CHE 105 Mid-Term Examination I 15 February 1996 University of Kentucky Department of Chemistry
1. A substance that appears to be a pure liquid yields a white, crystalline powder when the liquid is evaporated. The original substance wasA. a homogeneous mixture. B. a heterogeneous mixture. C. a pure substance. D. a compound.
2. A 2.0 L sample of a cola has a density of 1.079 g/mL. What is the mass of the sample in grams? kilograms?A. 1.9 x 106 g, 1.9 x 103 kg B. 2.2 x 103 g, 2.2 kg C. 1.9 x 103 g, 1.9 kg D. 2.2 x 103 g, 2.2 x 106 kg
3. Which of the following is/are true?A. The protons and neutrons make up most of the size of the atom. B. Each atom of an element has the same mass number. C. An ion is formed by the loss or gain of electrons. D. Both (B) and (C) are true.
4. The symbol for a cation with a mass number of 40, an atomic number of 20, and a charge of 2+ isA. 4020Ca2+ B. 4020Zr2+ C. 4018Ar2+ D. 2020Ca2+
5. How many protons(p), neutrons(n) and electrons(e) are in a 7Li+ ion?A. p = 7, n = 7, e = 6 B. p = 4, n = 3, e = 3 C. p = 3, n = 4, e = 2 D. p = 3, n = 4, e = 4
6. Which of the following are true statements?1. Ionic compounds will conduct electricity in the solid form. 2. Most molecular compounds are hard, brittle substances at room temperature. 3. The majority of elements in the periodic table are classified as metals. 4. Most ionic compounds will dissolve in water.
A. 1 and 3 B. 1 and 2 C. 2 and 4 D. 3 and 4
7. The formulas for the following polyatomic ions chromate, chlorate, phosphate areA. CrO4-, ClO4-, PO4- B. CrO4-, ClO32-, PO43- C. CrO42-, ClO3-, PO43- D. CrO4-, ClO3-, PO43-
8. Which of the following is correct?A. The formula for the molecular compound copper (II) sulfate is Cu2SO4. B. The formula for the ionic compound dinitrogen pentoxide is N2O5. C. The formula for the ionic compound iron (III) sulfate is Fe2(SO4)3. D. The formula for the ionic compound phosphorus tribromide is PBr3.
9. What is the correct name of IF5?A. Iodine fluoride B. Iodine pentafluoride C. Iodine (V) fluoride D. Iodine fluorine
10. Germanium is produced for the electronics industry by reacting germanium tetrachloride with very pure magnesium to produce germanium and magnesium chloride. The balanced chemical equation for this process isA. GeCl4 + Mg ---> 4 MgCl + Ge B. GeCl4 + Mg ---> MgCl2 + Ge C. GeCl4 + 2 Mg ---> 2 MgCl2 + Ge D. GeCl4 + Mg ---> MgCl4 + Ge
11. The balanced chemical equation for the complete combustion of methanol (CH3OH) isA. 2 CH3OH + O2 ---> 2 CO + 2 H2O B. 2 CH3OH + 3 O2 ---> 2 CO2 + 4 H2O C. CH3OH + O2 ---> CO2 + 2 H2O D. CH3OH + 3 O ---> CO2 + 2 H2O
12. The molar mass of calcium nitrate Ca(NO3)2 isA. 164.09 g/mol B. 70.08 g/mol C. 148.09 g/mol D. 150.08 g/mol
13. How many atoms are in a 4.0 x 10-2 g sample of N2 gas?A. 1.7 x 1021 B. 2.1 x 105 C. 8.6 x 1020 D. 1.6 x 1024
14. What is the empirical formula of an oxide of vanadium that is 61.4% vanadium by mass?A. VO B. VO2 C. V2O3 D. V2O4
15. How many grams of water will react with 1.5 g magnesium nitride according to the following balanced reactionMg3N2 + 6 H2O ---> 2 NH3 + 3 Mg(OH)2
A. 1.6 g B. 9.0 g C. 0.27 g D. 50. g
16. When 2.00 moles of ammonia reacted with 3.00 moles of oxygen according to the equation4 NH3 + 5 O2 ---> 4 NO + 6 H2O
it was found that 1.50 moles of NO were formed. Calculate the theoretical yield of NO, the % yield of NO and the actual yield of H2O.
A. 2.4 moles NO, 63%, 2.25 moles H2O B. 2 moles NO, 75%, 2.25 moles H2O C. 2 moles NO, 25%, 3.00 moles H2O D. 2.4 moles NO, 37%, 3.60 moles H2O
17. A solutionA. is a heterogeneous mixture of two or more substances. B. is always a liquid. C. is always colorless. D. is a homogeneous mixture of two or more substances.
18. How much water must be added to a 0.500 L solution of 0.400 M HCl to produce a 0.100 M HCl solution? (Assume volumes are additive.)A. 2.0 L B. 1.5 L C. 2.5 L D. 1.0 L
19. The net ionic equation for the reaction of an aqueous solution of calcium chloride with an aqueous solution of sodium carbonate isA. CaCl2(aq) + Na2CO3(aq) ---> CaCO3(s) + 2 NaCl(aq) B. Na+(aq) + Cl-(aq) ---> NaCl(s) C. Ca2+(aq) + CO32-(aq) ---> CaCO3(s) D. CaCl2(aq) + 2 NaHCO3(aq) ---> Ca(HCO3)2(s) + 2 NaCl(aq)
20. To determine the concentration of lead(II) ions in an unknown sample, an excess of 0.5 M sodium chloride was mixed with 5.0 mL of the unknown sample. 0.1059 g of solid was collected. What is the molarity of lead ions in the sample?A. 0.021 M B. 0.087 M C. 7.6 x 10-5 M D. 0.076 M
21. A reaction which is exothermicA. gives off heat to the surroundings. B. absorbs heat from the surroundings. C. is path dependent. D. Both (A) and (C)
22. A total of 12.0 kJ of heat flows into 500 g of water originally at 25.0oC. What is the final temperature of the water? The specific heat of water is 4.184 J/goC.A. 5.7 oC B. 30.7 oC C. 5.7 x 10-3 K D. 19.3 oC
23. Given thatdelta Ho H2(g) ---> 2 H(s) 436.4 kJ Br2(g) ---> 2 Br(s) 192.5 kJ H2(g) + Br2(s) ---> 2 HBr(s) -104 kJ
calculate delta Ho for
H(s) + Br(s) ---> HBr(s)
A. -733 kJ B. +733 kJ C. +366 kJ D. -366 kJ
24. Which statement(s) is(are) true?A. Visible light is another name for all electromagnetic radiation. B. Wavelength is measured in Hz. C. Electromagnetic radiation can be described both as a wave and a particle. D. (A) and (C) are true.
25. What is the energy of one mole of photons that have a frequency of 2.5 x 1010 Hz?A. 1.7 x 10-23 J B. 4.8 x 10-12 J C. 10. J D. 8.0 x 10-36 J