Assigment 2 - Zumdahl - Chemistry - Chapter 3

39. An element consists of 1.40% of an isotope with mass 203.973 u, 24.10% of an isotope with mass 205.9745 u, 22.10% of an isotope with mass 206.9759 u, and 52.40% of an isotope with mass 207.9766 u. Calculate the average atomic mass, and identify the element 41. The element rhenium (Re) has two naturally occurring isotopes, 185Re and 187Re, with an average atomic mass of 186.207 u. Rhenium is 62.60% 187Re, and the atomic mass of 187Re is 186.956 u. Calculate the mass of 185Re 49. Diamond is a natural form of pure carbon. What number of atoms of carbon are in a 1.00-carat diamond (1.00 carat = 0.200 g)? 67. What amount (moles) is represented by each of these samples? a. 150.0 g Fe2O3 b. 10.0 mg NO2 c. 1.5 x 1016 molecules of BF3 75. Calculate the percent composition by mass of the following compounds that are important starting materials for synthetic polymers: a. C3H4O2 (acrylic acid, from which acrylic plastics are made) c. C3H3N (acrylonitrile, from which Orlon is made) 79. Fungal laccase, a blue protein found in wood-rotting fungi, is 0.390% Cu by mass. If a fungal laccase molecule contains four copper atoms, what is the molar mass of fungal laccase? 81. Express the composition of each of the following compounds as the mass percents of its elements. a. formaldehyde, CH2O c. acetic acid, HC2H3O2 85. A compound that contains only carbon, hydrogen, and oxygen is 48.64% C and 8.16% H by mass. What is the empirical formula of this substance? 95. Cumene is a compound containing only carbon and hydrogen that is used in the production of acetone and phenol in the chemical industry. Combustion of 47.6 mg cumene produces some CO2 and 42.8 mg water. The molar mass of cumene is between 115 and 125 g/mol. Determine the empirical and molecular formulas. 95. C3H4, C9H12 113. The compound cisplatin, Pt(NH3)2Cl2, has been studied as an antitumor agent. Cisplatin is synthesized as follows: What mass of cisplatin can be produced from 100. g of K2PtCl4 and sufficient NH3? 119. Coke is an impure form of carbon that is often used in the industrial production of metals from their oxides. If a sample of coke is 95% carbon by mass, determine the mass of coke needed to react completely with 1.0 ton of copper(II) oxide 125. What mass of hydrogen peroxide should result when 1.50 g barium peroxide is treated with 88.0 mL hydrochloric acid solution containing 0.0272 g HCl per mL? What mass of which reagent is left unreacted? 133. Bornite (Cu3FeS3) is a copper ore used in the production of copper. When heated, the following reaction occurs: If 2.50 metric tons of bornite is reacted with excess O2 and the process has an 86.3% yield of copper, what mass of copper is produced?