# CHM 1040: Final 4/4

 Suppose you are building bird houses. The bird houses require ten nails and four pieces of wood each. Which of the following is not an exact relationship (ratio) between the number of nails and the number of pieces of wood you would need to build more than one birdhouse? A) 4 boxes of nails, 100 pieces of wood ﻿﻿﻿﻿﻿ Consider the generic reaction A + B —? C. This is an example of a A) synthesis. In an acid-base reaction, a weak acid would not form as much water as the same amount of strong acid. A) True B) False B) False Calculate the number of atoms in 42.6 amu of nitrogen. E) 1, exactly A) 3.0 What is a decomposition reaction? A) One reactant yielding product(s) If you wanted to create laboratory workbooks and you had 15 front covers, 21 back covers and 64 blank sheets of paper, how many workbooks could you assemble if 1 workbook = 1 front cover + 5 blank sheets + 1 back cover? D) 12 How many grams of iron (III) chloride may be formed when 43g of iron and 160g of Cl2 are reacted? 2Fe(s) + 3Cl2(s)-> 2FeCl3 D) 125g It is possible for only an oxidation to occur in a reaction. A) True B) False B) False Oxidation must occur with reduction. Which of the following reactions could be classified as a double-displacement reaction? A) Pb(NO3)2 (aq) + H2S (aq) --? 2HNO3 (aq) + PbS (s) (OK) ﻿ How many grams of hydrogen are required to form 180 grams of water?2H2 + O2 -> 2H2O D) 20 Calculate the mass, in grams, of 1.51 mol of carbon tetrachloride, CCl4. D) 232.25 It is not important to balance a chemical equation in order to see the number relationships. A) True B) False B) False In order to know how much of each substance reacts, it is very important to balance the equation. n an oxidation-reduction reaction, C) metals lose electrons. In the reaction: 2Fe(s) + 3Cl2(g) ->2FeCl3(s) (same as question 8), if 43 grams of iron were reacted, how many grams of Cl2 would be needed? B) 82 If 65g of iron react with 170g of Cl2, and the actual yield of FeCl3(s) was 43g, what would the percentage yield be? 2Fe(s) + 3Cl2(g) ->2FeCl3(s) D) 23 A compound containing magnesium and oxygen contains 43.2% Mg by mass. What is a possible formula for the compound? B) MgO2 What mass of oxygen contains the same number of atoms as 32.0 g of sulfur? A) 16.0 g What evidence is there that ions separate in solution? E) Charge may be carried by such a solution. A gross is a dozen dozen, or 144 items. Suppose you have 14 1/2 gross of ping-pong balls in your warehouse. How many ping-pong balls is this? D) 2088 On the basis of the general solubility rules, which of the following compounds should be insoluble in water? E) FeS What is the mass of nitrogen atoms in amu's? 1.2 x 10-24 C) 1.7 x 1025 Which of the following statements is false? C) If a reactant is left over after a reaction, it was the limiting reactant. Which of the following is not one of the four "driving forces" that pull reactants to form products during chemical reactions? A) Formation of a product. In one word, why do we use average atomic masses for the elements? A) isotopes On the basis of the solubility rules, which of the following should be soluble in water? E) KOH If 1000 HCl units and 1000 HCN units were dissolved in water, the relative amounts of species in solution would be shown as _____(HCN is a weak acid): E) H+< Cl-< HCN < HCl A) H+ ? Cl-> HCN > CN- A store has oranges which are, on average, 2.3 oranges per pound. If navel oranges cost \$0.79/lb, how many oranges (to the nearest whole orange, of course) will \$5.00 buy? B) 15 If 65g of iron react with 170g of Cl2, how many grams of FeCl3(s) product could be formed? 2Fe(s) + 3Cl2(g) ->2FeCl3(s) C) 190 What is the net charge of a precipitate formed by two aqueous solutions? D) Neutral, because an insoluble salt compound is formed. Which two compounds have the same empirical formula? D) C2H5OH and C6H18O3 Which of the following reactions could be classified as an oxidation-reduction reaction? B) Zn (s) + 2 HCl (aq) --? H2 (g) + ZnCl2 (aq) How many moles of K2CO3 would be formed by the complete reaction of 0.75 moles of KO2 in the reaction: 4KO2(s) + 2CO2(g) -> 2K2CO3(s) +3O2? C) 1.5 From the number of grams of a single product formed in a balanced chemical reaction, you may determine D) How many total grams of all reactants were used up. Knowing the percent yield and the actual yield (in grams), one could determine: B) B & C Calculate the mass percent composition of calcium in Ca(NO3)2. B) 24.4% Determine the number of vanadium atoms in 1.2 x 10-24 g of vanadium. C) 1.4 x 1018 In the reaction: 2Fe(s) + 3Cl2(g) ->2 FeCl3(s), if 43 grams of iron were reacted, how many moles of iron were reacted? B) 0.77 What type of reaction is responsible when a free element is converted to a compound? D) Oxidation-reduction A compound with molar mass of approximately 80 g/mol has the following composition (mass percent): C: 75.9%, H: 6.4%, and N: 17.7%. What is its molecular formula? C) C5H5N In the reaction: 2Fe(s) + 3Cl2(g) ->2FeCl3(s) (same as question 8), if 43 grams of iron were reacted, how many grams of FeCl3 could be produced? C) 125 The mass of hydrogen is 1g/mol, so in the reaction:2H2(g) + C(s) -> CH4(g), 2 grams of hydrogen will fully react with one gram of carbon. A) True B) False B) False A certain acid-base reaction resulted in the formation of the salt, RbNO3, in addition to water. Which acid-base pair could have been used? E) RbOH, HNO3 Eleven moles of water are produced by the reaction of hydrogen and oxygen: 2H2 + O2 -> 2H2O. How many moles of oxygen were used? A) 5.5 How many moles of water may be formed when 12 moles of hydrogen gas are mixed with 11 moles of oxygen gas and are allowed to react? 2H2 + O2 --> 2H2O C) 12 Which compound has the highest percent by mass magnesium? B) MgO 46. _______ ions are those that do not participate directly in a reaction. B) Spectator If 65g of iron react with 170g of Cl2, which reactant is limiting? 2Fe(s) + 3Cl2(g) ->2FeCl3(s) B) Fe Which has the greatest percent by mass of nitrogen: 100 g of ammonia, or 1 kg of ammonia? A) They both have the same mass percent composition of nitrogen. Which compound has a molar mass closest to 100 g/mol? C) C7H10 When oxalate ion is mixed with a calcium sulfate solution, solid calcium oxalate is formed. Identify the net ionic equation for this reaction. A) Ca2+ (aq) + C2O42-(aq) --? CaC2O4 (s) (OK) If magnesium were to react with the non-metal fluorine, how many electrons would each Mg atom lose, and how many would each F atom gain? A) Mg: 2; F: 1 Which statement about empirical formulas is false? B) No two compounds may have the same empirical formula. Calculate the molar mass of lead(II) nitrate (in g/mol). A) 331.2 Which is a valid, general definition of a salt? B) The compound besides water that is formed in an acid-base reaction. Fill in the blanks with the words or phrases that make the most sense: "If a certain sample of an element contains ____ atom(s), the sample weighs _____." B) Avogadro's number of ... the molar mass Given the balanced reaction: CCl4 + 2HF -? 2HCl + CCl2F2, identify which statement is incorrect. E) A product mixture containing 20g of HCl indicates 20g of HF reacted. Suppose a gross of ping-pong balls weighs 3 kilograms. A client wants to fill his truck with ping-pong balls, and his truck will transport only 1000 kg. How many ping-pong balls may he carry? D) 50,000 In the reaction 2Fe(s) + 3Cl2(g) -> 2FeCl3(s), Which of the following statements is incorrect? C) 6 moles of chlorine gas will produce 9 moles of FeCl2 (s). Authorkieu ID82732 Card SetCHM 1040: Final 4/4 DescriptionCHM 1040: Final 4/4 Updated2011-04-30T04:45:53Z Show Answers