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Unformatted text preview: G © Annuals TD Qmsms ("w (Ll-l 1 dub Sample Exam # 1 Problem S 3Q; Many of these problems are easy but a good warm up. CHM 2045 exam problems are often 2 or 3 step problems. Students seems to ﬁnd these difﬁcult because they have not done enough questions in 4 t05 minutes. problems to comfortable in solving our CHM 2045 students should be able to do any of these problems in 4 minutes or less 1. A 52.5 lb bag oftopsoil will cover 12 3 pounds of topsoil will be required to cover a 2) 5.192; 103 lbs 5) 7.98 x10 3 lbs *1)5.19x1061bs 4) 9.33 x108le 39.88211104le 2. Which of the following name formula pairs are NOT CORRECT? A) Lead (II) sulfate. PbSO4 B) Phosphine. PH3 C) Nitric oxide. NO D) Manganese (IV) oxide. M11402 E) Ammonium acetate. NH4CH3C02 F) Calcium oxide. CaO G) Aluminum sultite. A12(SO_~.)2 H) Lead (II) sulﬁte. P131303 1) Cobalt (III) oxide. C0203 I) Beryllium phosphate. Be3(P04)2 quare feet to a depth of 1.5 inches. How many plot 205 m by 315 m to a depth of 6.5 cm? K) Aluminum iodide. A113 L) Calcium floride. CaF; M) Potassium permanganate. KMHO4 N) Sodium chlorate NagCIO3 O) Ammonium carbonate. (NH4)2C03 3. Magnesium has three isotopes: 24Mg [23.935042 u]. 35Mg [24.985836 u] and 26Mg [25.982593 u]. Knowing that the atomic mass of Magnesium is 24.31 1.1 and the percent abundance of 24Mg is 78.99%. calculate the percent abundance of 25Mg. 1) 12.04% 2) 11.51% 3) 9.50% 4) 6.25% 5) 21.01% 4. A package of aluminum foil contains 100 ft2 and has a mass of 1 lb. Find the thickness of aluminum foil in mm. The density of Aluminum is 2.70g/cm". Note: 1 lb=45.36g. ' 1) 0001311131 2) 0.0046mm 3) 0.018mm 4) 0.0013mm 5) 0.46mm , 4‘ ® @ @ e o / 5. As part of an experiment to determine the density of a new plastic deveIOper. you measure the volume of a solid sample. Your four trials yield volumes of 14.4lcm". 14.37 ems. 14.38 cm}, and 14.39 cm3. Measurements of other scientists in the lab give an average volume of 14.61 c1113. Which of the following statements represents the best analysis of your data? 1.) Your results have low precision and high accuracy. 2.) Your results have high precision and high aCCuracy. 3.) Your results have greater precision than accuracy. 4.) Your results have greater accuracy than precision. 5.) You have been using a faulty instrument to measure the volume. -it’ — - . j . lL_.i - I 6. Which of the following is the greatest mass? ' 5/? 1.)7.8x10"fg g.) 5.5x103ng 3.)6.6><102ug .5. . ' I 4.) 1.3 x10” pg {\Sj)1.4 x104 mg m; '35 [Ila J 7". Atoms X. Y. Z and R have the following nuclear compositions: 410 410 “2 412 [86 X 183 Y 136 Z 185 R Which 2 are isotopes? 1.)X&Y 2.)X&R 3.)Y&R 4.)Z&R 5.)X&Z 8. Which ofthe following is NOT a chemical change? a. rusting b. copper conducting electricity c. ﬁreworks going off d. leaves producing sugar e. wood burning 9. Which of these are molecular compounds? 1 . CO 2- A12(SO4)3 3. CthO3 4. PC15 5. NHZCH3 1.)2and3 2.)I,4and5 3.) 4 and 5 4.) 2. 3 and 5 5.) i only 10. Which of the following is a heterogeneous mixture? I) mortar (a mixture of calcium carbonate and sand) 2) gasoline 3) antifreeze (a mixture of water and ethylene glycol) 4) sodium chloride dissolved in water 5) the air trapped inside a balloon (not including the balloon) ‘ ® @ @ (9 @ © 1 1. At 0 0C. a bottle contains 325 mL of water in its liquid state. What is the volume of the water after it freezes (at 0 E’C)? The densities of liquid water and ice at 0 0C are 1.000 gx’mL and 0.91? g/mL, respectively. 1) 27.0 mL 2) 298 m1. 3) 325 m1. 4) 354 mL 5) 391 mL centimeters? The volume of a sphere is (4f3)rrr3 . I)L4?X10Q7mn3 2)L47X10Q3mn3 3) 1.4? >< 10'2" cm3 4)r47x10*4mn3 12. The radius ofa lithium atom is 152 pm. What is the volume of a lithium atom is cubic 5)1.47 >< 10? cm3 13. An element consists of two isotopes. The abundance of one isotope is 95.72% and its atomic mass is 114.9041 u. The atomic mass ofthe second isotope is 1 12.9043 u. What is the average atomic mass of the element? 1)]13.9u 2)]13.0u 3)]13.9u :4)114.8u 5)]15.1u 14. Rutherford bombarded gold foil with alpha (0.) particles and found that a small percentage of the particles were deﬂected. Which of the following was 1191 accounted for by the model he proposed for the structure of atoms? 1) the small size of the nucleus 2) the charge on the nucleus 3) the total mass of the atom 4) the existence of protons 5) the presence of electrons outside the nucleus Sample problems 1. Gadolinium oxide. a colorless powder which absorbs carbon dioxide from the air. contains 86.?6 mass % Gd. Determine its empirical formula. A. Gd203 B. Gd302 C. Gd304 D. Gd403 E. GdO 2. Combustion of 1.780 g of an unknown hydrocarbon (CxHy) produced 5.8? g C02 and an unknown amount of H20. Which is closest to the empirical formula of the hydrocarbon? A. CH3 H. CH4 C.C2H3 D. (33th3 E. C3H4 3. The reaction of ammonia and sulfuric acid is used to commercially produce fertilizer, ammonium sulfate. If 22.? g ammonia and 54.8 g sulfuric acid are used, which reactant is in excess and how many grams of it are in excess? A. NH3, 19g B. NH3,3.7g C.NH3‘13.2g D. H2304‘35.8g E. sto.h 32.1 g 4. Write a balanced net-ionic equation for the reaction of aqueous solutions of potassium sulfate and calcium bromide. (aq) A. 2K+(aq)+ 2Br'(aq}—> 2KBr(aq) B. 304' (aq) + 2K"‘(aq) a Kgsomq) C. Ca2+(aq)+ seizing) 9 0180469) D. 216 (mg) + (332+ (aq)+ 2Br' (an + 30421519) a men (090 + CaSOi (s) E. K304(aq) + CaBr2(aq)% Ca2804(s) + K+ (aq) + Br' (aq) 5. When 14.8 g of methane and 52.0 g of chlorine gas undergo a reaction that has a 76.4% yield, what mass of chloromethane [CH3C1] forms? Hydrogen chloride also forms. . 49.1 g chloromethane 46.7 g chloromethane 37.0 g chloromethane . 35.2 g chloromethane 27.9 g chloromethane mvow> 6. Potassium chlorate decomposes to form potassium chloride and oxygen gas. A 0.892 g sample of impure potassium chlorate yields 0.217 g of oxygen. What was the mass p_e_rcent of potassium chlorate in the original sample? A. 93.2 % B. 62.1 % C. 81.0 "/o D. 52.7 % E. 99.9 "/0 1. What is the percent yield for the reaction: PC13(3)+ C1269) "4 PC1509) if 1 19.3 g of PC15 is formed when 61.3 g ofClz reacts with excess PC13? A. 195 % B. 33.7 % C. 66.3 % D. 51.4 % E. 43.7 % 2. Aluminum oxide (used as an adsorbent or a catalyst for organic reactions) forms when aluminum reacts with oxygen. 4 A1(s) + 3 oztg) —> 2 A1203{S) A mixture of 82.49 g of aluminum and 1 17.65 g ofoxygen is allowed to react. What mass of aluminum oxide can be formed? A.155.8g B. 200.2g C.249.9g D.311.7g E.374.9g 3. Which respOnse includes all of the following salts that are insoluble in water. and no others? LKI ILAgI III. (NH4)2C03 IV. Pb(CH3COO)2 V. PbSO4 A. II, III and IV B. I C. II and V D. III, IV, and V E. II and IV 4. In the following reaction, what ions, if any, are spectator ions? Pb(NO3)2(aq) + 2 NaCl(aq) —> PbC12(s) + 2 NaN03(aq) A. Pb2+(aq), Cl'(aq) B. NaYaq), N03'(aq) C. Pb2*(aq). NOgIaq) D. Na'Yaq), Cl'(aq) E. There are no spectator ions 5. Select the correct name and chemical formula for the precipitate that forms when the following reactants are mixed. CuC12(aq) + Na2C03(aq) —+ A. copperﬂ) carbonate, Cu2C03 B. copperﬂl) carbonate, CuzCO3 C. copper(l) carbonate, CuCO3 D. copperﬂl) carbonate, CuCO; E. sodium chloride, NaCl 6. The chemical formula of ammonium sulfate is: A.NH3SO4 B. NH2\$O3 C. (NI-l4)2SO4 D. NH4803 E. NO3SO4 ?. Balance the following equation using the smallest possible whole numbers. What is the coefﬁcient of P120? / MggNg + 6 H20 —) 3 Mg(OH)2+ 2/ NH3 A.5 B7 C3 D.4 E.6 8. It is desired to produce 5.00 moles of H3PO4 by the reaction shown below. Due to losses in puriﬁcation of the product. only a ?S% yield is expected. 3 H2804 + Ca3(PO4)2 “—> 2 H3P04 + 3 C3304 What mass of Ca3(PO4)2 (310.2 gfmol) should be used? A. kg Ca3(PO4)2 B. 1.0 kg CangO4)2 ’L 51 Q. \$1 In. C. 1.2. kg Ca3(P04)2 D. 1.6 kg (32130304); E. C83fP04)2 9. A compound is composed of 24.2% cepper. 22.0% chlorine, and 48.8% oxygen. If the molecular mass of this compound is 526 g, what is the molecular forle_a of the compound? A. CUC1203 CUCiOm CUQCIZOg CU2C14016 10. How many grams of water can be produced from the combustion 0117.2 g ot‘C5H12? A. 25.8 g B. 4.3 g C. 52.5 g D. 103.2 g E. 0.72 g 11. Write a balanced chemical equation for the reaction of iron and oxygen to yield iron(lll) oxide. A. Fe + 3 02 ‘9 2 F6203 B. Fe + 0 % F60 C. 4Fe+3 0292178303 D. 2 Fe + 02 '9 F8203 E. 3 Fe + 02 9 F6303 12. When 7.8 g of hydrochloric acid reacts with 5.6 g manganese (IV) oxide. how many grams of manganese {II} chloride can be formed? Water and chlorine gas are also products. - A. 8.1 g manganese (ll) chloride B. 6.? g manganese (II) chloride C. 26.9 g manganese (ll) chloride D. 22.1 g manganese (II) chloride ...
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