A hot air balloon of 811m³ is made from 8.50kg of materials. The outside atmosphere is 1.00 atm, and 18C and pure N₂ atmosphere. • CH4 + 2 O2 --> CO₂ + 2H₂O dHrxn = -890 kJ • All heat from CH4 burning goes into all the air originally in the balloon before heating • SN2 = 0.55 J/gC What mass in grams of CH4 needed to be burned to achieve neutral buoyancy? 0 24.7 margin of error +/- 3%

A hot air balloon of 811m³ is made from 8.50kg of materials. The outside atmosphere is 1.00 atm, and 18C and pure N₂ atmosphere. • CH4 + 2 O2 --> CO₂ + 2H₂O dHrxn = -890 kJ • All heat from CH4 burning goes into all the air originally in the balloon before heating • SN2 = 0.55 J/gC What mass in grams of CH4 needed to be burned to achieve neutral buoyancy? 0 24.7 margin of error +/- 3%

Chemistry for Engineering Students

4th Edition

ISBN:9781337398909

Author:Lawrence S. Brown, Tom Holme

Publisher:Lawrence S. Brown, Tom Holme

Chapter9: Energy And Chemistry

Section: Chapter Questions

Problem 9.102PAE: 9.102 A runner generates 418 kJ of energy per kilometer from the cellular oxidation of food. The...

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9.63 Reactions of hydrocarhons are often studied in the petroleum industry. One example is 2C3H8(g)C6H6(l)+5H2(g) , with H = 698 kJ. If 35 L of propane at 25C and 0.97 atm is to be reacted, how much heat must he supplied?
9.102 A runner generates 418 kJ of energy per kilometer from the cellular oxidation of food. The runner's body must dissipate this heat or the body will overheat. Suppose that sweat evaporation is the only important cooling mechanism. If you estimate the enthalpy of evaporation of water as 44 kJ/mol and assume that sweat can he treated as water, describe how you would estimate the volume of sweat that would have to be evaporated if the runner runs a 10-km race.
How much heat is produced when loo mL of 0.250 M HCl (density, 1.00 g/mL) and 200 mL of 0.150 M NaOH (density, 1.00 g/mL) are mixed? HCl(aq)+NaO(aq)NaCl(aq)+H2O(l)H298=58kJ If both solutions are at the same temperature and the heat capacity of the products is 4.19 J/g C, how much will the temperature increase? What assumption did you make in your calculation?
When 50.0 g of 0.200 M NaCl(aq) at 24.1 C is added to 100.0 g of 0.100 M AgNO3(aq) at 24.1 C in a calorimeter, the temperature increases to 25.2 C as AgCl(s) forms. Assuming the specific heat of the solution and products is 4.20 J/g C, calculate the approximate amount of heat in joules produced.
Peanuts and peanut oil are organic materials and bum in air. How many burning peanuts does it take to provide the energy to boil a cup of water (250 mL of water)? To solve this problem, we assume each peanut, with an average mass of 0.73 g, is 49% peanut oil and 21% starch; the remainder is noncombustible We further assume peanut oil is palmitic acid, C16H32O2, with an enthalpy of formation of 848.4 kJ/mol. Starch is a long chain of C6H10O5 units, each unit having an enthalpy of formation of 960 kJ.
When one mol of KOH is neutralized by sulfuric acid, q=56 kJ. (This is called the heat of neutralization.) At 23.7C, 25.0 mL of 0.475 M H2SO4 is neutralized by 0.613 M KOH in a coffee-cup calorimeter. Assume that the specific heat of all solutions is 4.18J/gC, that the density of all solutions is 1.00 g/mL, and that volumes are additive. (a) How many mL of KOH is required to neutralize H2SO4? (b) What is the final temperature of the solution?
Acetylene (C2H2) and butane (C4H10) are gaseous fuels with enthalpies of combustion of 49.9 kJ/g and 49.5 kJ/g. respectively. Compare the energy available from the combustion of a given volume of acetylene to the combustion energy from the same volume of butane at the same temperature and pressure.
The addition of 3.15 g of Ba(OH)28H2O to a solution of 1.52 g of NH4SCN in loo g of water in a calorimeter caused the temperature to fall by 3.1 C. Assuming the specific heat of the solution and products is 4.20 J/g C, calculate the approximate amount of heat absorbed by the reaction, which can be represented by the following equation: Ba(OH)28H2O(s)+2NH4SCN(aq)Ba(SCN)2(aq)+2NH3(aq)+10H2O(l)
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9.104 An engineer is using sodium metal as a cooling agent in a design because it has useful thermal properties. Looting up the heat capacity, the engineer finds a value of 28.2 J mol-l °C-l. Carelessly, he wrote this number down without units. As a result, it was later taken as specific heat. (a) What would he the difference between these two values? (b) Would the engineer overestimate the ability of sodium to remove heat from the system or underestimate it because of this error? Be sure to explain your reasoning.
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In earlier times, ethyl ether was commonly used as an anesthetic. It is, however, highly flammable. When five milliliters of ethyl ether, C4H10O(l)(d=0.714g/mL), are burned in a bomb calorimeter, the temperature rises from 23.5C to 39.7C. The calorimeter contains 1.200 kg of water and has a heat capacity of 5.32 kJ/C. (a) What is qH2o? (b) What is qcal? (c) What is q for the combustion of 5.00 mL of ethyl ether? (d) What is q for the combustion of one mole of ethyl ether?