Question Points Possible Points Earned 1 2 3 4 5 6 7 Name Section GENERAL CHEMISTRY I EXAM 1 FALL 2015 15 10 10 10 15 20 20 Total Question 1 A rectangular box with length 3 1 m width 2 5 m and height 1 1 m has a mass of 125 kg a What is the density of the box in kilograms per cubic meter kg m3 b Express the density of the box in milligrams per milliliter mg mL c What volume in m3 does a 36 7 kg box of the same density occupy Complete the following table Question 2 Symbol Atomic Protons Neutrons Electrons Mass 61 46 108 12 13 12 86Rb 26 30 23 Question 3 a There are two known isotopes of bromine 79Br and 81Br Given that the average atomic mass of bromine is 79 90 amu calculate the percent abundance of each isotope b Element X has three known isotopes 104X 106X and 107X If the percent abundance for each isotope is 21 3 52 6 and 26 1 respectively what is the average atomic mass of element X Complete the following table Question 4 Name Formula Potassium Bromide Sodium Hypochlorite Copper II Sulfite Trisulfur Octafluoride Ammonium Nitrite Li2CO3 N2O4 Ca3N2 Fe2 Cr2O7 3 Cs2Se Question 5 4 C3H5N3O9 12 CO2 10 H2O 6 N2 O2 Above is the balanced reaction for the decomposition of nitroglycerin a Calculate the number of oxygen atoms in 321 grams of nitroglycerin b Calculate the mass in grams of nitrogen in 25 6 grams of nitroglycerin c It is determined that there are 2 71 x 1024 carbon atoms in a sample of nitroglycerin i How many moles of nitroglycerin are there ii If the entire nitroglycerin sample decomposes what mass of water will be formed Question 6 A 5 71 gram sample of a hydrous compound is heated until only an anhydrous compound remains The mass of the compound after heating is 3 65 grams It is then determined that the anhydrous compound is 39 8 copper 40 1 oxygen and 20 1 sulfur a What is the empirical formula of the anhydrous compound b If the molecular weight of the anhydrous compound is 159 6 g mol what is its molecular formula c Calculate the moles of anhydrous compound and the moles of water lost during the heating process d What is the formula of the original hydrous compound Question 7 Butane C4H10 reacts with oxygen gas to produce carbon dioxide and water a Write the balanced chemical reaction for the combustion of butane b Suppose 26 3 grams of butane react with 53 4 grams of oxygen gas i Calculate the maximum mass of carbon dioxide that can be formed ii Calculate the mass in grams of the excess reagent iii If only 42 3 grams of carbon dioxide are produced calculate the percent yield for the reaction
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