Name: Justin Roth College ID: 0360782 Thomas Edison State College General Chemistry I (CHE-111) Section no.:4 Semester and year: January 2016 Written Assignment 4: Chemical Reactions Answer all assigned questions and problems and show all work. 1. Write the (a) balanced equation for the formation of liquid water from hydrogen and oxygen gas and use it to explain the following terms: (b) chemical reaction (c) reactant (d) product. (12 points) a.H2 O2=H2O b. Hydogen and Oxygen joined together to form Water. c. Hydrogen and Oxygen are the starting substances in the chemical reaction. d. H2O is formed from the reaction 2. Balance the following equations: (18 points) a. C O2 ? CO2 b. CO O2 ? 2CO2 c. Na H2O ? H2 2NaOH d. Zn HCl ? ZnCl2 H2 e. 2NaOH H2SO4 ? 2H2O Na2SO4 f. 2NH3 3CuO? 3Cu N2 3H2O 3. Calculate the mass in grams of iodine (I2) that will react completely with 20.4 g of aluminum (Al) to form aluminum iodide (AlI3). (5 points) 2AI 3I2=2AII3 3×0.756=2.268 20.4/26.98=.756 moles 2.268x 126.9 =287g (Reference: Chang 3.47) 4. The annual production of sulfur dioxide from burning coal and fossil fuels auto exhaust and other sources is about 26 million tons. The equation for the reaction is S(s) O2(g) ? SO2(g) How much sulfur (in tons) present in the original materials would result in that quantity of SO2?(5 points) 1.3×10^7tons S (Reference: Chang 3.69) 5. Each copper(II) sulfate unit is associated with five water molecules in crystalline opper(II) sulfate pentahydrate (CuSO4·5H2O). When this compound is heated in air above 100oC it loses the water molecules are also its blue color: .300 mol H2O If 9.60 g of CuSO4are left after heating 15.01 g of the blue compound calculate the number of moles of water originally present in the compound. (5 points) 63.546 32.026 4×16 5(2 x1.01 16)= 249.711/16 5(15.01/9.60)=7.86 moles (Reference: Chang 3.73) 6. The fertilizer ammonium sulfate [(NH4)2SO4] is prepared by the reaction between ammonia (NH3) and sulfuric acid: 2 NH3(g) H2SO4(aq) ? (NH4)2SO4(aq) How many kilograms of NH3 are needed to produce 1.00 × 105 kg of (NH4)2SO4? (5 points) (1.00e5 kg (NH4)2SO4 / 1) * (1000 g (NH4)2SO4 / 1 kg (NH4)2SO4) * (1 mol (NH4)2SO4 / 132.1402 g (NH4)2SO4) * (2 mol NH3 / 1 mol (NH4)2SO4) * (17.031 g NH3 / 1 mol NH3) * (1 kg NH3 / 1000 g NH3) = 25777.16698 kg NH3. (Reference: Chang 3.77) 7. Nitric acid (NO) reacts with oxygen gas to form nitrogen dioxide (NO2) a dark brown gas: 2NO(g) O2(g) ? 2NO2(g) In one experiment 0.886 mole of NO is mixed with 0.503 mol of O2. a. Calculate which of the two reactants is the limiting reagent. (5 points). NO b. Calculate also the number of moles of NO2 produced. (5 points) .886 mol NO2 is produced c. What reactant is left over and how much of it is left over? (5 points) 1.92g O2 (Reference: Chang 3.83) 8. Propane (C3H8) is a component of natural gas and is used in domestic cooking and heating. It burns according to the following reaction: C3H8 O2 ? CO2 H2O a. Balance the equation representing the combustion of propane in air. (5 points) C3H8 5O2?3CO2 4H2O b. How many grams of carbon dioxide can be produced by burning 20.0 pounds of propane the typical size of a BBG grill propane tank? Assume that oxygen is the excess reagent in this reaction. (5 points) 2.72×10^4g CO2 9. Hydrogen fluoride is used in the manufacture of Freons (which destroy ozone in the stratosphere) and in the production of aluminum metal. It is prepared by the reaction CaF2 H2SO4 ? CaSO4 2HF In one process 6.00 kg of CaF2 are treated with an excess of H2SO4 and yield 2.86 kg of HF. Calculate the percent yield of HF. (5 points) CaF2=6000g/78.0748=7.68 Mols HF= 2×76.8=153.6 Mass HF= 153.6x 20.0064 g/mol=3.075kg 2.86kg/3.075kg x100%=93% (Reference: Chang 3.89) 10. Certain race cars use methanol (CH3OH; also called wood alcohol) as a fuel. Methanol has a molecular mass of 32.0 g/mol and a density of 0.79 g/mL. The combustion of methanol occurs according to the following equation: 2CH3OH 3O2 ? 2CO2 4H2O In a particular reaction 2.00 L of methanol are reacted with 80.0 kg of oxygen. a. What is the limiting reactant? (5 points)= CH3OH b. What reactant and how many grams of it are left over? (5 points) O2- 2370g left c. How many grams of carbon dioxide is produced? (5 points) 2173g CO2 11. An iron bar weighed 664 g. After the bar had been standing in moist air for a month exactly one-eighth of the iron turned to rust (Fe2O3). Calculate the final mass of the iron bar and rust. (5 points) Fe3/4O2= ½ Fe2O3 Fe=56g/mol Fe2O3= 2x 56 3×16=160g/mol 581g 119g=700g (Reference: Chang 3.111)
