Chapter 12, Problem 38P

sample of natural gas is analyzed and found to be88.4% methane (CH4) and 11.6% ethane (C2H6) bymass. The standard enthalpy of combustion of methaneto gaseous carbon dioxide (CO2) and liquid water (H2O) is -891 kJ/mol. Write the equation for the combustionof gaseous ethane to carbon dioxide and water.Calculate the standard enthalpy of combustion of ethaneusing standard enthalpies of formation from Table R-11on page 975. Using that result and the standard enthalpyof combustion of methane in Table 15.3, calculate theenergy released by the combustion of 1 kg of natural gas.

When 1.000 g of ethylene glycol, C2H6O2, is burned at 25C and 1.00 atmosphere pressure, H2O(l) and CO2(g) are formed with the evolution of 19.18 kJ of heat. a Calculate the molar enthalpy of formation of ethylene glycol. (It will be necessary to use data from Appendix C.) b Gf of ethylene glycol is 322.5 kJ/mol. What is G for the combustion of 1 mol ethylene glycol? c What is S for the combustion of 1 mol ethylene glycol?

In a coffee-cup calorimeter, 150.0 mL of 0.50 M HCI is added to 50.0 mL of 1.00 M NaOH to make 200.0 g solution at an initial temperature of 48.2C. If the enthalpy of neutralization for the reaction between a strong acid and a strong base is 56 kJ/mol, calculate the final temperature of the calorimeter contents. Assume the specific heat capacity of the solution is 4.184 J/g C and assume no heat Joss to the surroundings.

The reaction enthalpy for oxidation of styrene, C8H8, has been measured by calorimetry. C8H8() + 10 O2(g) 8 CO2(g) + 4 H2O() rH = 4395.0 kJ/mol Use this value, along with the data from Table 4.2, to calculate the standard formation enthalpy of styrene, in kJ/mol. Table 4.2 Selected Standard Formation Enthalpies, fH, at 25C

The octane number of gasoline is based on a comparison of the gasolines behavior with that of 2,2,4-trimethylpentane, C8H18(), which is arbitrarily assigned an octane number of 100. The standard enthalpy of combustion of this compound is 5456.6 kJ/mol. (a) Write the thermochemical equation for the combustion of 2,2,4-trimethylpentane. (b) Use the standard enthalpies of formation in Appendix G to calculate the standard enthalpy of formation of 2,2,4-trimethylpentane.

One step in the manufacturing of sulfuric acid is the conversion of SO2(g) to SO3(g). The thermochemical equation for this process is SO2(g)+12O2(g)SO3(g)H=98.9kJ The second step combines the SO3 with H2O to make H2SO4. (a) Calculate the enthalpy change that accompanies the reaction to make 1.00 kg SO3(g). (b) Is heat absorbed or released in this process?

Dissolving 6.00 g CaCl2 in 300 mL of water causes the temperature of the solution to increase by 3.43 C. Assume that the specific heat of the solution is 4.18 J/g K and its mass is 306 g. (a) Calculate the enthalpy change when the CaCl2 dissolves. Is the process exothermic or endothermic? (b) Determine H on a molar basis for CaCl2(s)H2OCa2+(aq)+2Cl(aq)

When 1.000 g of gaseous butane, C4H10, is burned at 25C and 1.00 atm pressure, H2O(l) and CO2(g) are formed with the evolution of 49.50 kJ of heat. a Calculate the molar enthalpy of formation of butane. (Use enthalpy of formation data for H2O and CO2.) b Gf of butane is 17.2 kJ/mol. What is G for the combustion of 1 mol butane? c From a and b, calculate S for the combustion of 1 mol butane.

Indicate which state function is equal to heat, q, for each process described. a. The ignition of a sample in a bomb calorimeter, an unyielding, heavy metal chamberin which samples are burned for heat content analysis b.The melting of an icecube in a cup c.The cooling down ofthe inside of arefrigerator d.A fire in a fireplace