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All Textbook Solutions for Chemistry: An Atoms First Approach

A 10.00-mL sample of sulfuric acid from an automobile battery requires 35.08 mL of 2.12 M sodium hydroxide solution for complete neutralization. What is the molarity of the sulfuric acid? Sulfuric acid contains two acidic hydrogens.137CP A 6.50-g sample of a diprotic acid requires 137.5 mL of a 0.750 M NaOH solution for complete neutralization. Determine the molar mass of the acid.Citric acid, which can be obtained from lemon juice, has the molecular formula C6H8O7. A 0.250-g sample of citric acid dissolved in 25.0 mL of water requires 37.2 mL of 0.105 M NaOH for complete neutralization. What number of acidic hydrogens per molecule does citric acid have?140CP 141CP Tris(pentatluorophenyl)borane, commonly known by its aeronym BARF, is frequently used to initiate polymerization of ethylene or propylene in the presence of a catalytic transition metal compound. It is composed solely of C, F, and B; it is 42.23% C and 55.66% F by mass. a. What is the empirical formula of BARF? b. A 2.251-g sample of BARF dissolved in 347.0 mL of solution produces a 0.01267-M solution. What is the molecular formula of BARF?In a 1-L beaker, 203 mL of 0.307 M ammonium chromate was mixed with 137 mL of 0.269 M chromium(III) nitrite to produce ammonium nitrite and chromium(III) chromate. Write the balanced chemical equation for the reaction occurring here. If the percent yield of the reaction was 88.0%, what mass of chrornium(III) chromate was isolated?The vanadium in a sample of ore is converted to VO2+. The VO2+ ion is subsequently titrated with MnO4 in acidic solution to form V(OH)4+ and manganese(II) ion. The unbalanced titration reaction is MnO4(aq)+VO2++(aq)+H2O(l)V(OH)4+(aq)+Mn2+(aq)+H+(aq) To titrate the solution, 26.45 mL of 0.02250 M MnO4 was required. If the mass percent of vanadium in the ore was 58.1 %, what was the mass of the ore sample? Hint: Balance the titration reaction by the oxidation states method.The unknown acid H2X can be neutralized completely by OH according to the following (unbalanced) equation: H2X(aq)+OH(aq)X2(aq)+H2O(l) The ion formed as a product, X2, was shown to have 36 total electrons. What is element X? Propose a name for H2X. To completely neutralize a sample of H2X, 35.6 mL of 0.175 M OH solution was required. What was the mass of the H2X sample used?Three students were asked to find the identity of the metal in a particular sulfate salt. They dissolved a 0.14 72-g sample of the salt in water and treated it with excess barium chloride, resulting in the precipitation of barium sulfate. After the precipitate had been filtered and dried, it weighed 0.2327 g. Each student analyzed the data independently and came to different conclusions. Pat decided that the metal was titanium. Chris thought it was sodium. Randy reported that it was gallium. What formula did each student assign to the sulfate salt? Look for information on the sulfates of gallium, sodium, and titanium in this text and reference books such as the CRC Handbook of Chemistry and Physics. What further tests would you suggest to determine which student is most likely correct?You have two 500.0-mL aqueous solutions. Solution A is a solution of a metal nitrate that is 8.246% nitrogen by mass. The ionic compound in solution B consists of potassium, chromium, and oxygen; chromium has an oxidation state of + 6 and there are 2 potassiums and 1 chromium in the formula. The masses of the solutes in each of the solutions are the same. When the solutions are added together, a blood-red precipitate forms. After the reaction bas gone to completion, you dry the solid and find that it has a mass of 331.8 g. a. Identify the ionic compounds in solution A and solution B. b. Identify the blood-red precipitate. c. Calculate the concentration (molarity) of all ions in the original solutions. d. Calculate the concentration (molarity) of all ions in the final solution.Define the following terms: potential energy, kinetic energy, path-dependent function, state function, system, surroundings.Consider the following potential energy diagrams for two different reactions. Which plot represents an exothermic reaction? In plot a, do the reactants on average have stronger or weaker bonds than the products? In plot b, reactants must gain potential energy to convert to products. How does this occur?What is the first law of thermodynamics? How can a system change its internal energy, E? What are the sign conventions for thermodynamic quantities used in this text?When a gas expands, what is the sign of w? Why? When a gas contracts, what is the sign of w? Why? What are the signs of q and w for the process of boiling water?5RQ High-quality audio amplifiers generate large amounts of heat. To dissipate the heat and prevent damage to the electronic components, heat-radiating metal fins are used. Would it be better to make these fins out of iron or aluminum? Why? (See Table 7- l for specific heat capacities.)Explain how calorimetry works to calculate H or E for a reaction. Does the temperature of the calorimeter increase or decrease for an endothermic reaction? For an exothermic reaction? Explain.What is Hesss law? When a reaction is reversed, what happens to the sign and magnitude of H for that reversed reaction? When the coefficients in a balanced reaction are multiplied by a factor n, what happens to the sign and magnitude of H for that multiplied reaction?Define the standard enthalpy of formation. What are standard states for elements and for compounds? Using Hess's law, illustrate why the formula Hreaction=npHf(products)nfHf(reactants) works to calculate H for a reaction.1ALQ 2ALQ A fire is started in a fireplace by striking a match and lighting crumpled paper under some logs. Explain all the energy transfers in this scenario using the terms exothermic, endothermic. system. surroundings, potential energy. and kinetic energy in the discussion.Liquid water turns to ice. Is this process endothermic or exothermic? Explain what is occurring using the terms system. surroundings. heat, potential energy. and kinetic energy in the discussion.5ALQ 6ALQ Consider 5.5 L of a gas at a pressure of 3.0 atm in a cylinder with a movable piston. The external pressure is changed so that the volume changes to 10.5 L. a. Calculate the work done, and indicate the correct sign. b. Use the preceding data but consider the process to occur in two steps. At the end of the first step, the volume is 7.0 L. The second step results in a final volume of 10.5 L. Calculate the work done, and indicate the correct sign. c. Calculate the work done if after the first step the volume is 8.0 L and the second step leads to a volume of 10.5 L. Does the work differ from that in part b? Explain. 7. In Question 6 the work calculated for the different conditions in the various pans of the question was different even though the system had the same initial and final conditions. Based on this information, is work a state function? a. Explain how you know that work is not a state function. b. Why does the work increase with an increase in the number of steps? c. Which two-step process resulted in more work, when the first step had the bigger change in volume or when the second step had the bigger change in volume? Explain.Explain why oceanfront areas generally have smaller temperature fluctuations than inland areas.Hesss law is really just another statement of the first law of thermodynamics. Explain.10ALQ 11Q 12Q Assuming gasoline is pure C8H18(l), predict the signs of q and w for the process of combusting gasoline into CO2(g) and H2O(g).14Q The enthalpy change for the reaction CH4(g)+2O2(g)CO2(g)+2H2O(l) is 891 kJ for the reaction as written. a. What quantity of heat is released for each mole of water formed? b. What quantity of heat is released for each mole of oxygen reacted?For the reaction HgO(s)Hg(l)+12O2(g),H=+90.7KJ: a. What quantity of heat is required to produce 1 mole of mercury by this reaction? b. What quantity of heat is required to produce 1 mole of oxygen gas by this reaction? c. What quantity of heat would be released in the following reaction as written? 2Hg(l)+O2(g)2HgO(s)17Q The enthalpy change for a reaction is a state function and it is an extensive property. Explain.Standard enthalpies of formation are relative values. What are Hfvalues relative to?The combustion of methane can be represented as follows: a. Use the information given above to determine the value of H for the combustion of methane to form CO2(g) and 2H2O(l). b. What is Hf for an element in its standard state? Why is this? Use the figure above to support your answer. c. How does H for the reaction CO2(g) + 2H2O (1) CH4(g) + O2(g) compare to that of the combustion of methane? Why is this?21Q 22Q 23Q 24Q 25E 26E Consider the following diagram when answering the questions below. a. Compare balls A and B in terms of potential energy in both the initial and final setups. b. Ball A has stopped moving in the figure on the right above, but energy must be conserved. What happened to the potential energy of ball A?Consider the accompanying diagram. Ball A is allowed to fall and strike ball B. Assume that all of ball As energy is transferred to ball B at point I, and that there is no loss of energy to other sources. What is the kinetic energy and the potential energy of ball B at point II? The potential energy is given by PE = mgz, where m is the mass in kilograms, g is the gravitational constant (9.81 m/s2), and z is the distance in meters.A gas absorbs 45 kJ of heat and does 29 kJ of work. Calculate E.A system releases 125 kJ of heat while 104 kJ of work is done on it. Calculate E.Calculate E for each of the following. a. q = 47 kJ, w = + 88 kJ b. q = +82 kJ, w = 47 kJ c. q = + 47 kJ, w = 0 d. In which of these cases do the surroundings do work on the system?A system undergoes a process consisting of the following two steps: Step 1: The system absorbs 72 J of heat while 35 J of work is done on it. Step 2: The system absorbs 35 J of heat while performing 72 J of work. Calculate E for the overall process.If the internal energy of a thermodynamic system is increased by 300. J while 75 J of expansion work is done, how much heat was transferred and in which direction, to or from the system?Calculate the internal energy change for each of the following. a. One hundred (100.) joules of work is required to compress a gas. At the same time, the gas releases 23 J of heat. b. A piston is compressed from a volume of 8.30 L to 2.80 L against a constant pressure of 1.90 atm. In the process, there is a heat gain by the system of 350. J. c. A piston expands against 1.00 atm of pressure from 11.2 L to 29.1 L. In the process, 1037 J of heat is absorbed.A sample of an ideal gas at 15.0 atm and 10.0 L is allowed to expand against a constant external pressure of 2.00 atm to a volume of 75.0 L. Calculate the work in units of kJ for the gas expansion.36E Consider a mixture of air and gasoline vapor in a cylinder with a piston. The original volume is 40. cm3. If the combustion of this mixture releases 950. J of energy, to what volume will the gases expand against a constant pressure of 650. torr if all the energy of combustion is converted into work to push back the piston?As a system increases in volume, it absorbs 52.5 J of energy in the form of heat from the surroundings. The piston is working against a pressure of 0.500 atm. The final volume of the system is 58.0 L. What was the initial volume of the system if the internal energy of the system decreased by 102.5 J?A balloon filled with 39.1 moles of helium has a volume of 876 L at 0.0C and 1.00 atm pressure. The temperature of the balloon is increased to 38.0C as it expands to a volume of 998 L, the pressure remaining constant. Calculate q, w, and E for the helium in the balloon. (The molar heat capacity for helium gas is 20.8 J/C mol.)40E One of the components of polluted air is NO. It is formed in the high-temperature environment of internal combustion engines by the following reaction: N2(g)+O2(g)2NO(g)H=180KJ Why are high temperatures needed to convert N2 and O2 to NO?42E Are the following processes exothermic or endothermic? a. When solid KBr is dissolved in water, the solution gets colder. b. Natural gas (CH4) is burned in a furnace. c. When concentrated H2SO4 is added to water, the solution gets very hot. d. Water is boiled in a teakettle.Are the following processes exothermic or endothermic? a. the combustion of gasoline in a car engine b. water condensing on a cold pipe c. CO2(s) CO2(g) d. F2(g)2F(g)The overall reaction in a commercial heat pack can be represented as 4Fe(s)+3O2(g)2Fe2O3(s)H=1652KJ a. How much heat is released when 4.00 moles of iron are reacted with excess O2? b. How much heat is released when 1.00 mole of Fe2O3 is produced? c. How much heat is released when 1.00 g iron is reacted with excess O2? d. How much heat is released when 10.0 g Fe and 2.00 g O2 are reacted?Consider the following reaction: 2H2(g)+O2(g)2H2O(l)H=572KJ a. How much heat is evolved for the production of 1.00 mole of H2O(l)? b. How much heat is evolved when 4.03 g hydrogen are reacted with excess oxygen? c. How much heat is evolved when 186 g oxygen are reacted with excess hydrogen?Consider the combustion of propane: C3H8(g)+5O2(g)3CO2(g)+4H2O(l)H=2221KJ Assume that all the heat in Example 7-3 comes from the combustion of propane. What mass of propane must be burned to furnish this amount of energy assuming the heat transfer process is 60.% efficient?Consider the following reaction: CH4(g)+2O2(g)CO2(g)+2H2O(l)H=891KJ Calculate the enthalpy change for each of the following cases: a. 1.00 g methane ics burned in excess oxygen. b. 1.00 103 L methane gas at 740. torr and 25C are burned in excess oxygen. The density of CH4(g) at these conditions is 0.639 g/L.49E The specific heat capacity of silver is 0.24 J/Cg. a. Calculate the energy required to raise the temperature of 150.0 g Ag from 273 K to 298 K. b. Calculate the energy required to raise the temperature of 1.0 mole of Ag by l.0C (called the molar heat capacity of silver). c. It takes 1.25 kJ of energy to heat a sample of pure silver from 12.0C to 15.2C. Calculate the mass of the sample of silver.A 500-g sample of one of the substances listed in Table 7-1 was heated from 25.2C to 55.1C, requiring 133 J to do so. Which substance was it?52E A 30.0-g sample of water at 280. K is mixed with 50.0 g water at 330. K. Calculate the final temperature of the mixture assuming no heat loss to the surroundings.A biology experiment requires the preparation of a water bath at 37.0C (body temperature). The temperature of the cold tap water is 22.0C, and the temperature of the hot tap water is 55.0C. If a student starts with 90.0 g cold water, what mass of hot water must be added to reach 37.0C?A 5.00-g sample of aluminum pellets (specific heat capacity = 0.89 J/C g) and a 10.00-g sample of iron pellets (specific heat capacity = 0.45 J/C g) are heated to 100.0C. The mixture of hot iron and aluminum is then dropped into 97.3 g water at 22.0C. Calculate the final temperature of the metal and water mixture, assuming no heat loss to the surroundings.Hydrogen gives off 120. J/g of energy when burned in oxygen, and methane gives off 50. J/g under the same circumstances. If a mixture of 5.0 g hydrogen and 10. g methane is burned, and the heat released is transferred to 50.0 g water at 25.0C, what final temperature will be reached by the water?57E A 110.-g sample of copper (specific heat capacity = 0.20 J/C g) is heated to 82.4C and then placed in a container of water at 22.3C. The final temperature of the water and copper is 24.9C. What is the mass of the water in the container, assuming that all the heat lost by the copper is gained by the water?In a coffee-cup calorimeter, 50.0 mL of 0.100 M AgNO3 and 50.0 mL of 0.100 M HCl are mixed to yield the following reaction: Ag+(aq)+Cl(aq)AgCl(s) The two solutions were initially at 22.60C, and the final temperature is 23.40C Calculate the heat that accompanies this reaction in kJ/mol of AgCl formed. Assume that the combined solution has a mass of 100.0 g and a specific heat capacity of 4.18J/Cg.In a coffee-cup calorimeter, 100.0 mL of 1.0 M NaOH and 100.0 mL of 1.0 M HCI are mixed. Both solutions were originally at 24.6C. After the reaction, the final temperature is 31.3C. Assuming that all the solutions have a density of 1.0 g/cm3 and a specific heat capacity of 4.18 J/Cg, calculate the enthalpy change for the neutralization of HCl by NaOH. Assume that no heat is lost to the surroundings or to the calorimeter.A coffee-cup calorimeter initially contains 125 g water at 24.2C. Potassium bromide (10.5 g), also at 24.2C, is added to the water, and after the KBr dissolves, the final temperature is 21.1C. Calculate the enthalpy change for dissolving the: salt in J/g and kJ/mol. Assume that the specific heat capacity of the solution is 4.18 J/C g and that no heat is transferred to the surroundings or to the calorimeter.In a coffee-cup calorimeter, 1.60 g NH4NO3 is mixed with 75.0 g water at an initial temperature of 25.00C. After dissolution of the salt, the final temperature of the calorimeter contents is 23.34C. Assuming the solution has a heat capacity of 4.18 J/C g and assuming no heat loss to the calorimeter, calculate the enthalpy change for the dissolution of NH4NO3 in units of kJ/mol.Consider the dissolution of CaCl2: CaCl2(s)Ca2+(aq)+2Cl(aq)H=81.5KJ An 11.0-g sample of CaCl2 is dissolved in 125 g water, with both substances at 25.0C. Calculate the final temperature of the solution assuming no heat Joss to the surroundings and assuming the solution has a speci.fic heat capacity of 4.18 J/Cg.Consider the reaction 2HCl(aq)+Ba(OH)2(aq)BaCl2(aq)+2H2O(l)H=118KJ Calculate the heat when 100.0 rnL of 0.500 M HCl is mixed with 300.0 mL of 0.100 M Ba(OH)2 Assuming that the temperature of both solutions was initially 25.0C and that the final mixture has a mass of 400.0 g and a specific heat capacity of 4.18 J/C g, calculate the final temperature of the mixture.The heat capacity of a bomb calorimeter was determined by burning 6.79 g methane (energy of combustion = 802 kJ/mol CH4) in the bomb. The temperature changed by 10.8C. a. What is the heat capacity of the bomb? b. A 12.6-g sample of acetylene, C2H2, produced a temperature increase of 16.9C in the same calorimeter. What is the energy of combustion of acetylene (in kJ/mol)?The combustion of 0.1584 g benzoic acid increases the temperature of a bomb calorimeter by 2.54C. Calculate the heat capacity of this calorimeter. (The energy released by combustion of benzoic acid is 26.42 kJ/g.) A 0.2130-g sample of vanillin (C8H8O3) is then burned in the same calorimeter, and the temperature increases by 3.25C. What is the energy of combustion per gram of vanillin? Per mole of vanillin?The enthalpy of combustion of solid carbon to form carbon dioxide is 393.7 KJ/mol carbon, and the enthalpy of combustion of carbon monoxide to form carbon dioxide is 283.3 KJ/mol CO. Use these data to calculate H for the reaction 2C(s)+O2(g)2CO(g)Combustion reactions involve reacting a substance with oxygen. When compounds containing carbon and hydrogen are combusted, carbon dioxide and water are the products. Using the enthalpies of combustion for C4H4 ( 2341 kJ/mol), C4H8 (2755 kJ/mol), and H2 (286 kJ/mol), calculate H for the reaction C4H4(g)+2H2(g)C4H8(g)Given the following data calculate H for the reaction On the basis of the enthalpy change, is this a useful reaction for the synthesis of ammonia?Given the following data 2ClF(g)+O2(g)Cl2O(g)+F2O(g)H=167.4KJ2ClF3(g)+2O2(g)Cl2O(g)+3F2O(g)H=341.4KJ2F2(g)+O2(g)2F2O(g)H=43.4KJ Calculate H for the reaction ClF(g)+F2(g)ClF3(g)71E Calculate H for the reaction 2NH3(g)+12O2(g)N2H4(l)+H2O(l) given the following data: 2NH3(g)+3N2O(g)4N2(g)+3H2O(l)H=1010.KJN2O(g)+3H2(g)N2H4(l)+H2O(l)H=317KJN2H4(l)+O2(g)N2(g)+2H2O(l)H=623KJH2(g)+12O2(g)H2O(l)H=286KJ Given the following data Ca(s)+2C(graphite)CaC2(s)H=62.8KJCa(s)+12O2(g)CaO(s)H=635.5KJCaO(s)+H2O(l)Ca(OH)2(aq)H=653.1KJC2H2(g)+52O2(g)2CO2(g)+H2O(l)H=1300.KJC(graphite)+O2(g)CO2(g)H=393.5KJ Calculate H for the reaction CaC2(s)+2H2O(l)Ca(OH)2(aq)+C2H2(g)Given the following data P4(s)+6Cl2(g)4PCl3(g)H=1225.6KJP4(s)+5O2(g)P4O10(s)H=2967.3KJPCI3(g)+Cl2(g)PCl5(g)H=84.2KJPCl3(g)+12O2(g)Cl3PO(g)H=285.7KJ calculate H for the reaction P4O10(s)+6PCl5(g)10Cl3PO(g)Give the definition of the standard enthalpy of formation for a substance. Write separate reactions for the formation of NaCl, H2O , C6H12O6, and PbSO4 that have H values equal to Hf for each compound.Write reactions for which the enthalpy change will be a. Hf for solid aluminum oxide. b. the standard enthalpy of combustion of liquid ethanol, C2H5OH(l). c. the standard enthalpy of neutralization of sodium hydroxide solution by hydrochloric acid. d. Hf for gaseous vinyl chloride, C2H3Cl(g). e. the enthalpy of combustion of liquid benzene, C6H6(l). f. the enthalpy of solution of solid ammonium bromide.77E Use the values of Hf in Appendix 4 to calculate H for the following reactions. (See Exercise 77 .) a. b. SiCl4(l)+2H2O(l)SiO2(s)+4HCl(aq) c. MgO(s)+H2O(l)Mg(OH)2(s)The Ostwald process for the commercial production of nitric acid from ammonia and oxygen involves the following steps: 4NH3(g)+5O24NO(g)+6H2O(g)2NO(g)+O2(g)2NO2(g)3NO2(g)+H2O(l)2HNO3(aq)+NO(g) a. Use the values of Hf in Appendix 4 to calculate the value of H for each of the preceding reactions. b. Write the overall equation for the production of nitric acid by the Ostwald process by combining the preceding equations. (Water is also a product.) Is the overall reaction exothermic or endothermic?Calculate H for each of the following reactions using the data in Appendix 4: 4Na(s)+O2(g)2Na2O(s)2Na(s)+2H2O(l)2NaOH(aq)+H2(g)2Na(s)+CO2(g)Na2O(s)+CO(g) Explain why a water or carbon dioxide fire extinguisher might not be effective in putting out a sodium fire.The reusable booster rockets of the space shuttle use a mixture of aluminum and ammonium perchlorate as fuel. A possible reaction is 3Al(s)+3NH4ClO4(s)Al2O3(s)+AlCl3(s)+3NO(g)+6H2O(g) Calculate H for this reaction The space shuttle Orbiter utilizes the oxidation of methylhydrazine by dinitrogen tetroxide for propulsion: 4N2H3CH3(l)+5N2O4(l)12H2O(g)+9N2(g)+4CO2(g) Calculate H for this reaction Consider the reaction 2ClF3(g)+2NH3(g)N2(g)+6HF(g)+Cl2(g)H=1196KJ Calculate H for CIF3(g).The standard enthalpy of combustion of ethene gas, C2H4(g), is 1411.1 kJ/mol at 298 K. Given the following enthalpies of formation, calculateHf for C2H4(g). CO2(g)393.5KJ/molH2O(l)285.8KJ/mol Water gas is produced from the reaction of steam with coal: C(s)+H2O(g)H2(g)+CO(g) Assuming that coal is pure graphite, calculate H for this reaction.86E 87E 88E Some automobiles and buses have been equipped to bum propane (C3H8). Compare the amounts of energy that can be obtained per gram of C3H8(g) and per gram of gasoline, assuming that gasoline is pure octane, C8H18(l). (See Example 7-11.) Look up the boiling point of propane. What disadvantages are there to using propane instead of gasoline as a fuel?The complete combustion of acetylene, C2H2(g), produces 1300. kJ of energy per mole of acetylene consumed. How many grams of acetylene must be burned to produce enough heat to raise the temperature of 1.00 gal water by 10.0c if the process is 80.0% efficient? Assume the density of water is 1.00 g/cm3 91AE One way to lose weight is to exercise! Walking briskly at 4.0 miles per hour for an hour consumes about 400 kcal of energy. How many hours would you have to walk at 4.0 miles per hour to lose one pound of body fat? One gram of body fat is equivalent to 7.7 kcal of energy. There are 454 g in 1 lb.Three gas-phase reactions were run in a constant-pressure piston apparatus as shown in the following illustration. For each reaction, give the balanced reaction and predict the sign of w (the work done) for the reaction. . If just the balanced reactions were given, how could you predict the sign of w for a reaction?Nitrogen gas reacts with hydrogen gas to form ammonia gas .Consider the reaction between nitrogen and hydrogen as depicted below: a. Draw what the container will look like after the reaction has gone to completion. Assume a constant pressure of 1 atm. b. Is the sign of work positive or negative, or is the value of work equal to zero for the reaction? Explain your answer.Combustion of table sugar produces CO2(g) and H2O( l). When 1.46 g table sugar is combusted in a constant-volume (bomb) calorimeter, 24.00 kJ of heat is liberated. a. Assuming that table sugar is pure sucrose, C12H22O11 (s), write the balanced equation for the combustion reaction. b. Calculate E in kJ/mol C12H22O11 for the combustion reaction of sucrose.96AE Consider the following cyclic process carried out in two steps on a gas: Step 1: 45 J of heat is added to the gas, and 10. J of expansion work is performed. Step 2: 60. J of heat is removed from the gas as the gas is compressed back to the initial state. Calculate the work for the gas compression in Step 2.Calculate H for the reaction 2K(s)+2H2O(l)2KOH(aq)+H2(g) A 5.00-g chunk of potassium is dropped into 1.00 kg water at 24.0c. What is the final temperature of the water after the preceding reaction occurs? Assume that all the heat is used to raise the temperature of the water. (Never run this reaction. It is very dangerous; it bursts into flame!)The enthalpy of neutralization for the reaction of a strong acid with a strong base is 56 kJ/mol water produced. How much energy will be released when 200.0 mL of 0.400 M HNO3 is mixed with 150.0 mL of 0.500 M KOH?100AE If a student performs an endothermic reaction in a calorimeter, how does the calculated value of H differ from the actual value if the heat exchanged with the calorimeter is not taken into account?In a bomb calorimeter, the reaction vessel is surrounded by water that must be added for each experiment. Since the amount of water is not constant from experiment to experiment, the mass of water must be measured in each case. The heat capacity of the calorimeter is broken down into two parts: the water and the calorimeter components. If a calorimeter contains 1.00 kg water and has a total heat capacity of 10.84 kJ/C, what is the heat capacity of the calorimeter components?The bomb calorimeter in Exercise 102 is filled with 987 g water. The initial temperature of the calorimeter contents is 23.32C. A 1.056-g sample of benzoic acid (Ecomb = 26.42 kJ/g) is combusted in the calorimeter. What is the final temperature of the calorimeter contents?104AE Consider the following equations: 3A+6B3DH=403KJ/molE+2FAH=105.2KJ/molCE+3DH=64.8KJ/mol Suppose the first equation is reversed and multiplied by 16, the second and third equations are divided by 2, and the three adjusted equations are added. What is the net reaction and what is the overall heat of this reaction?106AE At 298 K, the standard enthalpies of formation for C2H2(g) and C6H6(l) are 227 kJ/mol and 49 kJ/mol, respectively. a. Calculate H for C6H6(l)3C2H2(g) b. Both acetylene (C2H2) and benzene (C6H6) can be used as fuels. Which compound would liberate more energy per gram when combusted in air?108AE A sample of nickel is heated to 99.8C and placed in a coffee-cup calorimeter containing 150.0 g water at 23.5C. After the metal cools, the final temperature of metal and water mixture is 25.0C. If the specific heat capacity of nickel is 0.444 J/C g, what mass of nickel was originally heated? Assume no heat loss to the surroundings.Quinone is an important type of molecule that is involved in photosynthesis. The transport of electrons mediated by quinone in certain enzymes allows plants to take water, carbondioxide, and the energy of sunlight to create glucose. A 0.1964-g sample of quinone (C6H4O2) is burned in a bomb calorimeter with a heat capacity of 1.56 kJ/C. The temperature of the calorimeter increases by 3.2C. Calculate the energy of combustion of quinone per gram and per mole.Calculate H for each of the following reactions, which occur in the atmosphere. a. C2H4(g)+O3(g)CH3CHO(g)+O2(g) b. O3(g)+NO(g)NO2(g)+O2(g) c. SO3(g)+H2O(l)H2SO4(aq) d. 2NO(g)+O2(g)2NO2(g)Compare your answers from parts a and b of Exercise 69 of Chapter 3 with H values calculated for each reaction using standard enthalpies of formation in Appendix 4. Do enthalpy changes calculated from bond energies give a reasonable estimate of the actual values?Compare your answer from Exercise 72 of Chapter 3 to the H value calculated from standard enthalpies of formation in Appendix 4. Explain any discrepancies. .. 72. Acetic acid is responsible for the sour taste of vinegar. It can be manufactured using the following reaction: Use tabulated values of bond engines(Table 3-3) to estimate E for this reaction Consider a balloon filled with helium at the following conditions. 313 g He 1.00 atm 1910. L Molar Heat Capacity = 20.8 J/C mol The temperature of this balloon is decreased by 41.6C as the volume decreases to 1643 L, with the pressure remaining constant. Determine q, w, and E(in KJ) for the compression of the balloon.115CWP 116CWP 117CWP A swimming pool, 10.0 m by 4.0 m, is filled with water to a depth of 3.0 m at a temperature of 20.2C. How much energy is required to raise the temperature of the water to 24.6C?119CWP Calculate H for the reaction N2H4(l)+O2(g)N2(g)+2H2O(l) given the following data: Equation H(KJ) 2NH3(g)+3N2O(g)4N2(g)+3H2O(l) 1010 N2O(g)+3H2(g)N2H4(l)+H2O(l) 317 2NH3(g)+12O2(g)N2H4(l)+H2O(l) 143 H2(g)+12O2(g)H2O(l) 286 Which of the following substances have an enthalpy of formation equal to zero? a. Cl2(g) b. H2(g) c. N2(l) d. Cl(g)Consider 2.00 moles of an ideal gas that are taken from state A (PA = 2.00 atm, vA = 10.0 L) to state B (PB = 1.00 attn, VB = 30.0 L) by two different pathways: These pathways are summarized on the following graph of P versus V: Calculate the work (in units of J) associated with the two pathways. Is work a state function? Explain.For the process H2O(l)H2O(g) at 298 K and 1.0 atm, H is more positive than E by 2.5 kJ/mol. What does the 2.5 kJ/mol quantity represent?The sun supplies energy at a rate of about 1.0 kilowatt per square meter of surface area (1 watt = 1 J/s). The plants in an agricultural field produce the equivalent of 20. kg sucrose (C12H22O1l) per hour per hectare (1 ha = 10.000 m2). Assuming that sucrose is produced by the reaction 12CO2(g)+11H2O(l)C12H22O11(s)+12O2(g)H=5640KJ calculate the percentage of sunlight used to produce the sucrosethat is, determine the efficiency of photosynthesis.125CP The standard enthalpies of formation for S(g), F(g), SF4(g), and SF6(g) are +278.8, +79.0, 775, and +1209 KJ/mol, respectively. a. Use these data to estimate the energy of an SF bond. b. Compare your calculated value to the value given in Table 3-3. What conclusions can you draw? c. Why are the Hf values for S(g) and F(g) not equal to zero, since sulfur and fluorine are elements?Use the following standard enthalpies of formation to estimate the N-H bond energy in ammonia: N(g), 472.7 kJ/mol; H(g), 216.0 kJ/mol; NH3(g), 46.1 kJ/mol. Compare your value to the one in Table 3-3.The standard enthalpy of formation for N2H4(g) is 95.4 kJ/mol. Use this and the data in Exercise 127 to estimate the NN single bond energy. Compare this with the value in Table 3-3.The standard enthalpy of formation for NO(g) is 90. kJ/mol. Use this and the values for the O 9 O and N N bond energies to estimate the bond strength in NO.A piece of chocolate cake contains about 400 calories. A nutritional calorie is equal to 1000 calories (thermochemical calories), which is equal to 4.184 kJ. How many 8-in-high steps must a 180-lb man climb to expend the 400 Cal from the piece of cake? See Exercise 28 for the formula for potential energy.You have a l.00-mole sample of water at 30.C and you heat it until you have gaseous water at 140.C. Calculate q for the entire process. Use the following data. Specificheatcapacityofice=2.03J/CgSpecificheatcapacityofwater=4.18J/CgSpecificheatcapacityofsteam=2.02J/Cg H2O(s)H2O(l)Hfusion=6.02KJ/mol(at0C)H2O(l)H2O(g)Hvaporization=40.7KJ/mol(at100.C)A 500.0-g sample of an element at 195C is dropped into an ice--water mixture; 109.5 g ice melts and an ice--water mixture remains. Calculate the specific heat of the element. See Exercise 131 for pertinent information.A cubic piece of uranium metal (specific heat capacity = 0.117 J/C g) at 200.0C is dropped into 1.00 L deuterium oxide ("heavy water;" specific heat capacity = 4.21 I J/C g) at 25.5C. The final temperature of the uranium and deuterium oxide mixture is 28.5C. Given the densities of uranium (19.05 g/cm3) and deuterium oxide (1.11 g/mL). what is the edge length of the cube of uranium?On Easter Sunday, April 3, 1983, nitric acid spilled from a tank car near downtown Denver, Colorado. The spill was neutralized with sodium carbonate: 2HNO3(aq)+Na2CO3(aq)2NaNO3(aq)+H2O(l)+CO2(g) a. Calculate H for this reaction. Approximately 2.0 104 gal nitric acid was spilled. Assume that the acid was an aqueous solution containing 70.0% HNO3 by mass with a density of 1.42 glcm3. What mass of sodium carbonate was required for complete neutralization of the spill, and what quantity of heat was evolved? (Hf for NaNO3(aq) = 467 kJ/mol) b. According to The Denver Post for April 4, 1983, authorities feared that dangerous air pollution might occur during the neutralization. Considering the magnitude of H, what was their major concern?Using data from Chapter 2, calculate the change in energy expected for each of the following processes. a. Na(g)+Cl(g)Na+(g)+Cl(g) b. Mg(g)+F(g)Mg+(g)+F(g) c. Mg+(g)+F(g)Mg2+(g)+F(g). d. Mg(g)+2F(g)Mg2+(g)+2F(g)In Exercise 89 in Chapter 3, the Lewis structures for benzene (C6H6) were drawn. Using one of the Lewis Structures, estimate Hf for C6H6(g) using bond energies and given that the standard enthalpy of formation of C(g) is 717 kJ/mol. The experimental Hf value for C6H6 (g) is 83 kJ/mol. Explain the discrepancy between the experimental value and the calculated Hf value for C6H6(g).A gaseous hydrocarbon reacts completely with oxygen gas to form carbon dioxide and water vapour. Given the following data, determine Hf for the hydrocarbon: Hreaction=2044.5KJ/molhydrocarbonHf(CO2)=393.5KJ/molHf(H2O)=242KJ/mol Density of CO2 and H2O product mixture at 1.00 atm, 200.c = 0.751g/L. The density of the hydrocarbon is less than the density of Kr at the same conditions.1RQ 2RQ 3RQ 4RQ 5RQ 6RQ 7RQ 8RQ 9RQ Why do real gases not always behave ideally? Under what conditions does a real gas behave most ideally? Why?3ALQ 4ALQ 6ALQ 8ALQ 11ALQ 12ALQ 15ALQ 16ALQ Draw molecular-level views that show the differences among solids, liquids, and gases.20Q 21Q 22Q 23Q 24Q 25Q Consider two different containers, each filled with 2 moles of Ne(g). One of the containers is rigid and has constant volume. The other container is flexible (like a balloon) and is capable of changing its volume to keep the extemal pressure and internal pressure equal to each other. If you raise the temperature in both containers, what happens to the pressure and density of the gas inside each container? Assume a constant extemal pressure.27Q 28Q 29Q 30Q 31Q 32Q 33Q 34Q 35Q 36Q 37E 38E A sealed-tube manometer (as shown below) can be used to measure pressures below atmospheric pressure. The tube above the mercury is evacuated. When there is a vacuum in the flask, the mercury levels in both arms of the U-tube are equal. If a gaseous sample is introduced into the flask, the mercury levels are different. The difference h is a measure of the pressure of the gas inside the flask. If h is equal to 6.5 cm, calclate the pressure in the flask in torr, pascals, and atmospheres.40E A diagram for an open-tube manometer is shown below. If the flask is open to the atmosphere, the mercury levels are equal. For each of the following situations where a gas is contained in the flask, calculate the pressure in the flask in torr, atmospheres, and pascals. c. Calculate the pressures in the flask in parts a and b (in torr) if the atmospheric pressure is 635 torr.42E 43E 44E 45E 46E 47E 48E 49E 50E The Steel reaction vessel of a bomb calorimeter, which has a volume of 75.0 mL, is charged with oxygen gas to a pressure of 14.5 atm at 22C. Calculate the moles of oxygen in the reaction vessel.A 5.0-L flask contains 0.60 g O2 at a temperature of 22C. What is the pressure (in atm) inside the flask?53E A person accidentally swallows a drop of liquid oxygen, O2(l), which has a density of 1.149 g/mL. Assuming the drop has a volume of 0.050 mL, what volume of gas will be produced in the persons stomach at body temperature (37C) and a pressure of 1.0 atm?A gas sample containing 1.50 moles at 25C exerts a pressure of 400. torr. Some gas is added to the same container and the temperature is increased to 50.C. If the pressure increases to 800. torr, how many moles of gas were added to the container? Assume a constant-volume container.56E 57E What will be the effect on the volume of an ideal gas if the pressure is doubled and the absolute temperature is halved?59E 60E An ideal gas is contained in a cylinder with a volume of 5.0 102 mL at a temperature of 30.C and a pressure of 710. torr. The gas is then compressed to a volume of 25 mL, and the temperature is raised to 820.C. What is the new pressure of the gas?62E A sealed balloon is filled with 1.00 L helium at 23C and 1.00 atm. The balloon rises to a point in the atmosphere where the pressure is 220. torr and the temperature is 31C. What is the change in volume of the balloon as it ascends from 1.00 atm to a pressure of 220. torr?64E Consider the following reaction: 4Al(s)+3O2(g)2A12O3(s) It takes 2.00 L of pure oxygen gas at STP to react completely with a certain sample of aluminum. What is the mass of aluminum reacted?A student adds 4.00 g of dry ice (solid CO2) to an empty balloon. What will be the volume of the balloon at STP after all the dry ice sublimes (converts to gaseous CO2)?Air bags are activated when a severe impact causes a Steel ball to compress a spring and electrically ignite a detonator cap. This causes sodium azide (NaN3) to decompose explosively according to the following reaction: 2NaN3(s)2Na(s)+3N2(g) What mass of NaN3(s) must be reacted to inflate an air bag to 70.0 L at STP?Concentrated hydrogen peroxide solutions are explosively decomposed by traces of transition metal ions (such as Mn or Fe): 2H2O2(aq)2H2O(l)+O2(g) What volume of pure O2(g), collected at 27C and 746 torr, would be generated by decomposition of 125 g of a 50.0% by mass hydrogen peroxide solution? Ignore any water vapor that may be present.In 1897 the Swedish explorer Andre tried to reach the North Pole in a balloon. The balloon was filled with hydrogen gas. The hydrogen gas was prepared from iron splints and diluted sulfuric acid. The reaction is Fe(s)+H2SO4(aq)FeSO4(aq)+H2(g) The volume of the balloon was 4800 m3 and the loss of hydrogen gas during filling was estimated at 20.%. What mass of iron splints and 98% (by mass) H2SO4 were needed to ensure the complete filling of the balloon? Assume a temperature of 0C, a pressure of 1.0 atm during filling, and 100% yield.Sulfur trioxide, SO3, is produced in enormous quantities each year for use in the synthesis of sulfuric acid. S(s)+O2(g)SO2(g)2SO2(g)+O2(g)2SO3(g) What volume of O2(g) at 350.C and a pressure of 5.25 atm is needed to completely convert 5.00 g sulfur to sulfur trioxide?A 15.0-L rigid container was charged with 0.500 atm of krypton gas and 1.50 atm of chlorine gas at 350.C. The krypton and chlorine react to form krypton tetrachloride. What mass of krypton tetrachloride can be produced assuming 100% yield?An important process for the production of acrylonitrile (C3H3N) is given by the following equation: 2C3H6(g)+2NH3(g)+3O2(g)2C3H3N(g)+6H2O(g) A 150.-L reactor is charged to the following partial pressures at 25C: PC3H6=0.500MPaPNH3=0.800MPaPO2=1.500MPa What mass of acrylonitrile can be produced from this mixture (MPa = 106 Pa)?Consider the reaction between 50.0 mL liquid methanol, CH3OH (density = 0.850 g/mL), and 22.8 L O2 at 27C and a pressure of 2.00 atm. The products of the reaction are CO2(g) and H2O(g). Calculate the number of moles of H2O formed if the reaction goes to completion.Urea (H2NCONH2) is used extensively as a nitrogen source in fertilizers. It is produced commercially from the reaction of ammonia and carbon dioxide: 2NH3(g)+CO2(g)PressureHeatH2NCONH2(s)+H2O(g) Ammonia gas at 223C and 90. atm flows into a reactor at a rate of 500. L/min. Carbon dioxide at 223C and 45 atm flows into the reactor at a rate of 600. L/min. What mass of urea is produced per minute by this reaction assuming 100% yield?75E 76E 77E A compound has the empirical formula CHCl. A 256-mL flask, at 373 K and 750. torr, contains 0.800 g of the gaseous compound. Give the molecular formula.79E Given that a sample of air is made up of nitrogen, oxygen, and argon in the mole fractions 0.78 N2, 0.21 O2, and 0.010 Ar, what is the density of air at standard temperature and pressure?81E 82E 83E 84E Consider the flasks in the following diagram. What are the final partial pressures of H2 and N2 after the stopcock between the two flasks is opened? (Assume the final volume is 3.00 L.) What is the total pressure (in torr)?Consider the flask apparatus in Exercise 85, which now contains 2.00 L H2 at a pressure of 360. torr and 1.00 L N2 at an unknown pressure. If the total pressure in the flasks is 320. torr after the stopcock is opened, determine the initial pressure of N2 in the 1.00-L flask.87E At 0C a 1.0-L flask contains 5.0 102 mole of N2, 1.5 102 mg O2, and 5.0 1021 molecules of NH3. What is the partial pressure of each gas, and what is the total pressure in the flask?89E A tank contains a mixture of 52.5 g oxygen gas and 65.1 g carbon dioxide gas at 27C. The total pressure in the tank is 9.21 atm. Calculate the partial pressures of each gas in the container.91E Helium is collected over water at 25C and 1.00 atm total pressure. What total volume of gas must be collected to obtain 0.586 g helium? (At 25C the vapor pressure of water is 23.8 torr.)At elevated temperatures, sodium chlorate decomposes to produce sodium chloride and oxygen gas. A 0.8765-g sample of impure sodium chlorate was heated until the production of oxygen gas ceased. The oxygen gas collected over water occupied 57.2 mL at a temperature of 22C and a pressure of 734 torr. Calculate the mass percent of NaClO3 in the original sample. (At 22C the vapor pressure of water is 19.8 torr.)Xenon and fluorine will react to form binary compounds when a mixture of these two gases is heated to 400C in a nickel reaction vessel. A 100.0-mL nickel container is filled with xenon and fluorine, giving partial pressures of 1.24 atm and 10.10 atm, respectively, at a temperature of 25C. The reaction vessel is heated to 400C to cause a reaction to occur and then cooled to a temperature at which F2 is a gas and the xenon fluoride compound produced is a nonvolatile solid. The remaining F2 gas is transferred to another 100.0-mL nickel container, where the pressure of F2 at 25C is 7.62 atm. Assuming all of the xenon has reacted, what is the formula of the product?Methanol (CH3OH) can be produced by the following reaction: CO(g)+2H2(g)CH3OH(g) Hydrogen at STP flows into a reactor at a rate of 16.0 L/min. Carbon monoxide at STP flows into the reactor at a rate of 25.0 L/min. If 5.30 g methanol is produced per minute, what is the percent yield of the reaction?In the Mthode Champenoise, grape juice is fermented in a wine bottle to produce sparkling wine. The reaction is C6H12O6(aq)2C2H5OH(aq)+2CO2(g) Fermentation of 750. mL grape juice (density = 1.0 g/cm3) is allowed to take place in a bottle with a total volume of 825 mL until 12% by volume is ethanol (C2H5OH). Assuming that the CO2 is insoluble in H2O (actually, a wrong assumption), what would be the pressure of CO2 inside the wine bottle at 25C? (The density of ethanol is 0.79 g/cm3.)Hydrogen azide, HN3, decomposes on heating by the following unbalanced equation: HN3O(g)N2(g)+H2(g) If 3.0 atm of pure HN3(g) is decomposed initially, what is the final total pressure in the reaction container? What are the partial pressures of nitrogen and hydrogen gas? Assume the volume and temperature of the reaction container are constant.98E Some very effective rocket fuels are composed of lightweight liquids. The fuel composed of dimethylhydrazine [(CH3)2N2H2] mixed with dinitrogen tetroxide was used to power the Lunar Lander in its missions to the moon. The two components react according to the following equation: (CH3)2N2H2(l)+2N2O4(l)3N2(g)+4H2O(g)+2CO2(g) If 150 g dimethylhydrazine reacts with excess dinitrogen tetroxide and the product gases are collected at 127C in an evacuated 250-L tank, what is the partial pressure of nitrogen gas produced and what is the total pressure in the tank assuming the reaction has 100% yield?The oxides of Group 2A metals (symbolized by M here) react with carbon dioxide according to the following reaction: MO(s)+CO2(g)MCO3(s) A 2.85-g sample containing only MgO and CuO is placed in a 3.00-L container. The container is filled with CO2 to a pressure of 740. torr at 20.C. After the reaction has gone to completion, the pressure inside the flask is 390. torr at 20.C. What is the mass percent of MgO in the mixture? Assume that only the MgO reacts with CO2.101E 102E 103E 104E 105E 106E 107E 108E 109E 110E 111E 112E 113E 114E 115E 116E 117E 118E 119E 120E 121E 122E 123AE At STP, 1.0 L Br2 reacts completely with 3.0 L F2, producing 2.0 L of a product. What is the formula of the product? (All substances are gases.)125AE A 2.747g sample of manganese metal is reacted with excess HCl gas to produce 3.22 L H2(g) at 373 K and 0.951 atm and a manganese chloride compound (MnClx. What is the formula of the manganese chloride compound produced in the reaction?127AE Cyclopropane, a gas that when mixed with oxygen is used as a general anesthetic, is composed of 85.7% C and 14.3% H by mass. If the density of cyclopropane is 1.88 g/L at STP, what is the molecular formula of cyclopropane?The nitrogen content of organic compounds can be determined by the Dumas method. The compound in question is first reacted by passage over hot CuO(s): CompoundCuO(s)HotN2(g)+CO2(g)+H2O(g) The product gas is then passed through a concentrated solution of KOH to remove the CO2. After passage through the KOH solution, the gas contains N2 and is saturated with water vapor. In a given experiment a 0.253-g sample of a compound produced 31.8 mL N2 saturated with water vapor at 25C and 726 torr. What is the mass percent of nitrogen in the compound? (The vapor pressure of water at 25C is 23.8 torr.)130AE A 15.0L tank is filled with H2 to a pressure of 2.00 l02tm. How many balloons (each 2.00 L) can be inflated to a pressure of 1.00 atm from the tank? Assume that there is no temperature change and that the tank cannot be emptied below 1.00 atm pressure.A spherical glass container of unknown volume contains helium gas at 25C and 1.960 atm. When a portion of the helium is withdrawn and adjusted to 1.00 atm at 25C, it is found to have a volume of 1.75 cm3. The gas remaining in the first container shows a pressure of 1.710 atm. Calculate the volume of the spherical container.133AE A 20.0L stainless steel container at 25C was charged with 2.00 atm of hydrogen gas and 3.00 atm of oxygen gas. A spark ignited the mixture, producing water. What is the pressure in the tank at 25C? If the exact same experiment were performed, but the temperature was 125C instead of 25C, what would be the pressure in the tank?Metallic molybdenum can be produced from the mineral molybdenite, MoS2. The mineral is first oxidized in air to molybdenum trioxide and sulfur dioxide. Molybdenum trioxide is then reduced to metallic molybdenum using hydrogen gas. The balanced equations are MoS2(s)+72O2(g)MoO3(s)+2SO2(g)MoO3(s)+3H2(g)Mo(s)+3H2O(l) Calculate the volumes of air and hydrogen gas at 17C and 1.00 atm that are necessary to produce 1.00 103 kg pure molybdenum from MoS2. Assume air contains 21% oxygen by volume, and assume 100% yield for each reaction.136AE 137AE One of the chemical controversies of the nineteenth century concerned the element beryllium (Be). Berzelius originally claimed that beryllium was a trivalent element (forming Be3+ ions) and that it gave an oxide with the formula Be2O3. This resulted in a calculated atomic mass of 13.5 for beryllium. In formulating his periodic table, Mendeleev proposed that beryllium was divalent (forming Be2+ ions) and that it gave an oxide with the formula Be2O3. This assumption gives an atomic mass of 9.0. In 1894, A. Combes (Comptes Rendus 1894, p. 1221) reacted beryllium with the anion C5H7O2and measured the density of the gaseous product. Combess data for two different experiments are as follows: I II Mass 0.2022 g 0.2224 g Volume 22.6 cm3 26.0 cm3 Temperature 13C 17C Pressure 765.2 mm Hg 764.6 mm If beryllium is a divalent metal, the molecular formula of the product will be Be(C5H7O2)2; if it is trivalent, the formula will be Be(C5H7O2)3. Show how Combess data help to confirm that beryllium is a divalent metal.An organic compound contains C, H, N, and O. Combustion of 0.1023 g of the compound in excess oxygen yielded 0.2766 g CO2 and 0.0991 g H2O. A sample of 0.4831 g of the compound was analyzed for nitrogen by the Dumas method (see Exercise 129). At STP, 27.6 mL of dry N2 was obtained. In a third experiment, the density of the compound as a gas was found to be 4.02 g/L at 127C and 256 torr. What are the empirical and molecular formulas of the compound?140AE The total volume of hydrogen gas needed to fill the Hindenburg was 2.0 108 L at 1.0 atm and 25C. Given that Hf for H2O(l) is 286 kJ/mol, how much heat was evolved when the Hindenburg exploded, assuming all of the hydrogen reacted to form water?142AE

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