Fundamentals of General Chemistry, Exam #1 with Solutions

Exam 1 Practice Problems: This is not a "practice test", these are sample questions that will verify your readiness to take the exam. If you can complete these problems without help from your text and notes, then you are likely ready to take the exam. The problems in the set are NOT the exam questions, however the are very similar in context and difficlty. 1) A physical change A) occurs when propane is burned for heat. B) occurs when iron rusts. C) occurs when glucose is converted into energy within your cells. D) occurs when sugar is heated into caramel. E) occurs when water is evaporated. 2) How many significant figures are in the measurement, 0.0005890 g? A) 4 B) 8 C) 6 D) 7 E) 5 3) What answer should be reported, with the correct number of significant figures, for the following calculation? (433.621 ‐ 333.9) × 11.900 A) 1.187 × 10 3 B) 1.1868 × 103 C) 1.18680 × 10 3 D) 1.19 × 103 E) 1.186799 × 103 4) What does it mean to be an exact number? Give an example of an exact number. 5) What is the volume (in cm 3) of a 63.4 g piece of metal with a density of 12.86 g/cm3? A) .425 B) 19.5 C) 6.65 D) 4.93 E) none of the above 6) If 1.4% of the mass of a human body is calcium, how many kilograms of calcium are there in a 185‐pound man? D) 1.2 × 102 kg Ca A) 5.7 kg Ca B) 1.2 kg Ca C) 5.7 × 102 kg 7) A fishing boat accidentally spills 3.0 barrels of diesel oil into the ocean. Each barrel contains 42 gallons. If the oil film on the ocean is 2.5 × 102 nm thick, how many square meters will the oil slick cover? D) none of these C) 1.9 × 107 m2 B) 1.9 × 10‐3 m2 A) 1.9 × 106 m2 8) How many protons (p) and neutrons (n) are in an atom of A) 90 p, 38 n 90 Sr? 38 B) 38 p, 52 n C) 38 p, 90 n 9) What does "X" represent in the following symbol? 235 X 92 A) copper B) niobium C) tin D) uranium D) 52 p, 38 n E) palladium 10) Which of the following represent isotopes? A: 32 X 15 A) C and D B: 32 X 16 C: 31 X 15 D: 34 X 17 C) A and C B) A and D 1 D) A and B 11) Calculate the atomic mass of silver if silver has 2 naturally occurring isotopes with the following masses and natural abundances: Ag‐107 Ag‐109 106.90509 amu 108.90476 amu A) 108.00 amu 51.84% 48.46% B) 107.79 amu C) 108.32 amu 12) How many electrons are in the ion, Cu2+? A) 27 B) 64 D) 108.19 amu C) 31 13) What mass (in kg) does 5.84 moles of titanium (Ti) have? C) 0.280 kg A) 0.352 kg B) 0.632 kg E) 107.90 amu D) 29 D) 0.122 kg E) 0.820 kg 14) A covalent bond is best described as A) a bond between two polyatomic ions. B) the transfer of electrons. C) a bond between a metal and a polyatomic ion. D) the sharing of electrons between atoms. E) a bond between a metal and a nonmetal. 15) Identify the compound with ionic bonds. A) H2O B) Ne C) KBr D) CO E) O2 16) Identify the compound with covalent bonds. A) KBr B) CH4 C) NaCl D) Ne E) Mg 17) What is the empirical formula for C 4 H10O 2? A) CHO2 B) C2H5 O C) CH2 O D) CHO E) C2 H4O 18) Give the name for SnO. A) tin (III) oxide B) tin (II) oxide 19) Write the formula for strontium nitride. A) Sr(NO 3)2 B) Sr 3N2 C) tin (IV) oxide C) SrN D) tin (I) oxide D) Sr 2N3 E) Sr(NO 2)2 20) Determine the name for TiCO 3. Remember that titanium forms several ions. A) titanium (II) carbonate B) titanium (II) carbonite C) titanium carbonite D) titanium carbide E) titanium (I) carbonate 21) Determine the name for CoCl2∙6H2 O. Remember that Co forms several ions. A) cobalt (II) chloride heptahydrate B) cobalt (I) chloride C) cobalt (I) chloride heptahydrate D) cobalt (II) chloride hexahydrate E) cobalt chloride hydrate 22) What is the charge on the Cr ions in Cr 2O 3? A) 1+ B) 2‐ C) 2+ 2 D) 3+ 23) Write the name for FeS. A) iron (I) sulfide B) iron (I) sulfate C) iron sulfide 24) Write the formula for copper (II) sulfate pentahydrate. A) Cu2SO 3∙H5 B) CuS∙5H2 O C) Cu2S∙H2O D) iron (II) sulfate E) iron (II) sulfide D) CuSO4 ∙5H2O E) (CuSO4)5 D) 21.38 % E) 28.12 % 25) Determine the name for H 2 CO 3. A) carbonous acid B) hydrocarbonic acid C) dihydrogen carbonate D) hydrocarbide acid E) carbonic acid 26) Determine the name for aqueous HBr. A) hydrobromous acid B) hydrogen bromate C) hydrobromic acid D) bromic acid E) bromous acid 27) Give the name for H 2SO 4. A) persulfuric acid B) sulfuric acid C) sulfurous acid D) hyposulfurous acid E) persulfurous acid 28) Determine the name for N 2 O5 . A) nitrogen oxide B) dinitrogen pentoxide C) nitrogen (IV) oxide D) nitrogen (II) oxide E) nitrogen tetroxide 29) Calculate the mass percent composition of sulfur in Al 2 (SO 4 )3. A) 35.97 % B) 9.372 % C) 42.73 % 30) How many atoms of oxygen are contained in 47.6 g of Al 2(CO 3 )3? The molar mass of Al 2(CO 3 )3 is 233.99 g/mol. A) 3.68 × 1023 O atoms B) 1.23 × 1023 O atoms C) 1.10 × 1024 O atoms D) 2.87 × 1025 O atoms E) 2.96 × 1024 O atoms 31) How many SO3 ions are contained in 99.6 mg of Na 2 SO3 ? The molar mass of Na 2 SO3 is 126.05 g/mol. A) 2.10 × 1021 SO 3 ions B) 4.76 × 1020 SO 3 ions C) 1.52 × 1027 SO 3 ions D) 9.52 × 1020 SO 3 ions E) 1.05 × 1021 SO 3 ions 3 32) Determine the molecular formula of a compound that has a molar mass of 92.0 g/mol and an empirical formula of NO 2 . A) NO2 B) N2 O3 C) N3O 6 D) N2 O4 E) N2O 5 33) Determine the empirical formula for a compound that is 36.86% N and 63.14% O by mass. A) N2O 3 B) N2 O C) NO D) NO2 E) NO3 34) Write a balanced equation to show the reaction of gaseous ethane with gaseous oxygen to form carbon monoxide gas and water vapor. A) 2 CH 3 (g) + 5 O (g) → 2 CO (g) + 3 H2 O (g) B) 2 C 2 H6 (g) + 7 O 2 (g) → 4 CO2 (g) + 6 H2O (g) C) C2 H6 (g) + 7 O (g) → 2 CO2 (g) + 3 H2 O (g) D) C2 H6 (g) + 5 O (g) → 2 CO (g) + 3 H2O (g) E) 2 C 2 H6 (g) + 5 O 2 (g) → 4 CO (g) + 6 H2 O (g) 35) Balance the following equation. _____ C10H12 + _____ O2 → _____ H2 O + _____ CO 2 36) Methane and oxygen react to form carbon dioxide and water. What mass of water is formed if 0.80 g of methane reacts with 3.2 g of oxygen to produce 2.2 g of carbon dioxide? A) 4.0 g B) 1.8 g C) 3.7 g D) 2.2 g 37) Combustion analysis of 1.200 g of an unknown compound containing carbon, hydrogen, and oxygen produced 2.086 g of CO 2 and 1.134 g of H2O. What is the empirical formula of the compound? A) C3 H8O 2 B) C2H5 O2 C) C2 H5O D) C2H10O3 38) Nitrogen dioxide reacts with water to form nitric acid and nitrigen monoxide. How many moles of NO are formed from 8.44 moles of NO 2 if there is excess moles of water present? A) 1.83 moles NO B) 2.81 moles NO C) 25.3 moles NO D) 5.63 moles NO E) 8.44 moles NO 39) How many moles of nitrogen are formed when 58.6 g of potassium nitrate decomposes to form potassium oxide, molecular nitrogen and molecular oxygen? The molar mass of potassium nitrate is is 101.11 g/mol. A) 0.290 mol N2 B) 0.724 mol N2 C) 0.580 mol N2 D) 18.5 mol N 2 E) 1.73 mol N 2 40) Two samples of calcium fluoride are decomposed into their constituent elements. The first sample produced 0.154 g of calcium and 0.146 g of fluorine. If the second sample produced 294 mg of fluorine, how many g of calcium were formed? A) 2.80 × 102 g B) 3.09 × 10 2 g C) 0.280 g D) 0.309 g E) 3.13 g 41) Nitrogen dioxide reacts with water to form nitric acid and nitrigen monoxide. How many grams of water are required to form 75.9 g of HNO 3? Assume that there is excess NO 2 present. A) 21.7 g H2 O B) 26.5 g H2O C) 43.4 g H2 O D) 10.9 g H2O E) 38.0 g H2 O 42) Carbonic acid can form water and carbon dioxide upon heating. How much carbon dioxide is formed from 6.20 g of carbonic acid? H2CO 3 → H2O + CO 2 A) 4.40 g B) 8.80 g C) 6.20 g 4 D) 2.20 g 43) Give the percent yield when 28.16 g of CO 2 are formed from the combustion of 4.000 moles of C 8 H18 with 4.000 moles of O2 . A) 25.00% B) 12.50% C) 20.00% D) 50.00% 44) Lithium and nitrogen react in a combination reaction to produce lithium nitride: In a particular experiment, 3.50‐g samples of each reagent are reacted. The theoretical yield of lithium nitride is __________ g. A) 17.6 B) 8.7 C) 5.85 D) 2.93 E) 3.52 45) Which of the following solutions will have the highest concentration of chloride ions? A) 0.10 M sodium chloride B) 0.05 M calcium chloride C) 0.10 M magnesium chloride D) 0.10 M aluminium chloride E) All of these solutions have the same concentration of chloride ions. 46) How many liters of a 0.0550 M KCl solution contain 0.163 moles of KCl? A) 2.96 L B) 1.48 L C) 3.37 L D) 1.12 L E) 8.97 L 47) Determine the molarity of a solution formed by dissolving 468 mg of MgI 2 in enough water to yield 50.0 mL of solution. A) 0.0107 M B) 0.0337 M C) 0.0297 M D) 0.0651 M E) 0.0936 M 48) How many milliliters of a 0.266 M LiNO 3 solution are required to make 150.0 mL of 0.075 M LiNO 3 solution? A) 23.6 mL B) 18.8 mL C) 35.1 mL D) 42.3 mL E) 53.2 mL 49) A solution is prepared by mixing 50.0 mL of 0.100 M HCl and 10.0 mL of 0.200 M NaCl. What is the molarity of chloride ion in this solution? A) 0.117 B) 3.50 C) 0.0500 D) 8.57 E) 0.183 50) According to the following reaction, what mass of PbCl 2 can form from 235 mL of 0.110 M KCl solution? Assume that there is excess Pb(NO 3)2 . 2 KCl(aq) + Pb(NO3 )2 (aq) → PbCl2(s) + 2 KNO 3(aq) A) 3.59 g B) 5.94 g C) 1.80 g D) 7.19 g E) 1.30 g 51) What volume of 0.305 M AgNO 3 is required to react exactly with 155.0 mL of 0.274 M Na 2 SO4 solution? A) 345 mL B) 139 mL C) 173 mL D) 278 mL E) 581 mL 52) Which of the following is NOT a strong electrolyte? A) NaC 2H3 O2 B) LiOH C) MgCO3 53) Identify sugar. A) weak electrolyte, weak acid B) nonelectrolyte C) weak electrolyte, strong acid D) strong electrolyte, weak acid E) strong electrolyte, strong acid 5 D) Li2 SO4 E) CaCl2 54) Which of the following solutions will have the highest electrical conductivity? A) 0.10 M sodium iodide B) 0.10 M lithium bromide C) 0.050 M ammonium chloride D) 0.045 M aluminum sulfate E) 0.10 M potassium fluoride 55) How many of the following compounds are insoluble in water? potassium acetate A) 3 calcium sulfate strontium sulfide aluminum phosphate B) 1 C) 4 D) 0 E) 2 56) Which of the following pairs of aqueous solutions will form a precipitate when mixed? A) Hg2(NO3)2 + LiI B) NaCl + Li3 PO4 C) AgC2 H3O 2 + Cu(NO3)2 D) NH 4 NO3 + Li2 CO 3 E) None of the above solution pairs will produce a precipitate. 57) Identify the spectator ions in the following molecular equation. KBr(aq) + AgNO 3(aq) → AgBr(s) + KNO3(aq) A) K+ and NO3‐ B) K+ and Br ‐ C) Ag+ and Br ‐ D) Ag+ and NO3 ‐ E) There are no spectator ions in this reaction. 58) What reagent could not be used to separate Br ‐ from CO 3 2‐ when added to an aqueous solution containing both? A) Ca(NO3)2 (aq) B) AgNO 3 (aq) C) Fe(NO3 )2(aq) D) Cu(NO3)2 (aq) 59) Give the complete ionic equation for the reaction (if any) that occurs when aqueous solutions of MgSO 3 and HI are mixed. A) Mg2+(aq) + 2 I‐(aq) → MgI2 (s) B) 2 H+(aq) + SO32‐ (aq) + Mg 2+(aq) + 2 I‐(aq)→ H2SO 3(s) + MgI2 (aq) C) 2 H+(aq) + SO32‐ (aq) → H2 SO3 (s) D) 2 H+(aq) + SO32‐ (aq) → H2 O(l) + SO2(g) E) No reaction occurs. 60) Identify the polyprotic acid. A) H2SO 4 B) HCl C) Li(OH)2 61) Which of the following is an oxidation‐reduction reaction? A) Pb(C2H3 O2 )2(aq) + 2 NaCl(aq) → PbCl 2 (s) + 2 NaC 2 H3O 2(aq) B) Mg(s) + 2 HCl(aq) → MgCl2(aq) + H 2 (g) C) NaI(aq) + AgNO3(aq) → AgI(s) + NaNO 3(aq) D) HCl(aq) + LiOH(aq) → LiCl(aq) + H2 O(l) E) All of the above are oxidation‐reduction reactions. 6 D) NaOH E) NaCl 62) Determine the oxidation state of S in MgSO 4 . A) ‐2 B) +2 C) ‐4 D) +4 E) +6 Mg(s) + 2HCl(aq) → MgCl2(aq) + H 2 (g) B) +1 C) ‐2 D) +2 E) ‐1 D) Li E) Fe 63) Identify the oxidation state of H in H 2(g). A) 0 64) What element is undergoing oxidation (if any) in the following reaction? Zn(s) + 2 AgNO 3(aq) → Zn(NO 3)2 (aq) + 2 Ag(s) A) N B) Zn C) O D) Ag E) This is not an oxidation‐reduction reaction. 65) Determine the reducing agent in the following reaction. 2 Li(s) + Fe(C 2H3 O2 )2(aq) → 2 LiC 2H3 O2 (aq) + Fe(s) A) H B) O C) C 66) What is the concentration of FeCl 3 in a solution prepared by dissolving 20.0 g of FeCl3 in enough water to make 275 mL of solution? A) 2.23 × 103 M B) 0.448 M C) 4.48 × 10‐4 M D) 2.23 M 67) What is the concentration (M) of sodium ions in 4.57 L of a .398 M Na 3P solution? 68) A FeCl3 solution is 0.175 M. How many mL of a 0.175 M FeCl 3 solution are needed to make 450. mL of a solution that is 0.300 M in Cl ‐ ion? A) 257 mL B) 771 mL C) 0.771 mL D) It is not possible to make a more concentrated solution from a less concentrated solution. 69) When 31.2 mL of 0.500 M AgNO3 is added to 25.0 mL of 0.300 M NH 4Cl, how many grams of AgCl are formed? A) 2.24 g B) 1.07 g C) 6.44 g D) 3.31 g 70) How many milliliters of 0.550 M hydriodic acid are needed to react with 15.00 mL of 0.217 M CsOH? A) 38.0 mL B) 0.169 mL C) 0.0263 mL D) 5.92 mL 71) The titration of 80.0 mL of an unknown concentration H 3 PO4 solution requires 126 mL of 0.218 M KOH solution. What is the concentration of the H 3PO4 solution (in M)? A) 0.138 M B) 0.0461 M C) 1.03 M D) 0.114 M E) 0.343 M 7 Answer Key E A D An exact number has an infinite number of significant figures even though we typically don't write many of them out. If there are 26 people in a classroom, there are exactly 26.00000.... people in that room. There is no possibility of a half person, so this is an exact whole number with no ambiguity. 5) D 6) B 7) A 8) B 9) D 10) C 11) D 12) A 13) C 14) D 15) C 16) B 17) B 18) B 19) B 20) A 21) D 22) D 23) E 24) D 25) E 26) C 27) B 28) B 29) E 30) C 31) B 32) D 33) A 34) E 35) C10H12 + 13 O 2 → 6 H2O + 10 CO 2 36) B 37) A 38) B 39) A 40) D 1) 2) 3) 4) 41) D 42) A 43) A 44) C 45) D 46) A 47) B 48) D 49) A 50) A 51) D 52) C 53) B 54) D 55) E 56) A 57) A 58) B 59) D 60) A 61) B 62) E 63) A 64) B 65) D 66) B 67) 1.19 68) A 69) B 70) D 71) D 8