Pad 7:42 PM 92% Old Dominion University 52) For the reaction Agl(s) + ½ Br2(g) A
ID: 543055 • Letter: P
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Pad 7:42 PM 92% Old Dominion University 52) For the reaction Agl(s) + ½ Br2(g) AgBr(s) + ½ 12(s), r _-54.0 kJ AH for AgBrs)-100.4 kl/mol Ah" for Br2(g) = +30.9 kJ/mol The value of AH for Agl(s) is: a) -123.5 kJ/mol b) +77.3 kJ/mol c) +61.8 kJ/mol d) -77.3 k/mol e) -61.8 kJ/mol 53) Using standard enthalpies of formation, determine the enthalpy of the following reaction according to the method requested (12 points) CH4 (g) + 2O2(g) CO2 (g) + 2H20 (l) CH -74.87 kJ/mol, CO2(g)--393.5 kJ/mol, H2O (l)-285.8 kJ/mol Combined: 54) Complete combustion of a 0.720 moles of ethane gas with excess oxygen gas releases 787.0 kJ of heat Answer the following questions 2GHs(g) +702(g) 4CO2(g) + 6H20(1) a) What mass of oxygen gas reacted? b) What mass of carbon dioxide is formed? c) Calculate the total change in energy (AE) for the combustion if the volume increased from 15.0OL to 16.67L at a constant pressure of 1.000 atm. (101.325/ = 1.000 L-atm) d) Calculate Hnn for the reaction in kJ 2C2Helg) +702(g) 4CO2(g) + 6H20(l) Hxn-? e) Calculate the H for ethane given CO2 (gl H2O (1) Hr =-393.5 kJ/mol AHr-285.8 kJ/molExplanation / Answer
a. 2C2H6(g) + 7O2(g) ----------> 4CO2(g) + 6H2O(l)
2moles of C2H6 react with 7 moles of O2
0.72 moles of C2H6 react with = 7*0.72/2 = 2.52 moles of O2
mass of O2 = no of moles * gram molar mass
= 2.52*32 = 80.64g
b. 2 moles of C2H6 react with O2 to gives 4 moles of CO2
0.72 moles of C2H6 react with O2 to gives = 4*0.72/2 = 1.44moles of Co2
mass of CO2 = no of moles * gram molarmass
= 1.44*44 = 63.36g
c. DE = PDV
= 1*(16.67-15) = 1.67L-atm
= 1.67*101.325J = 169.2J
d. 2C2H6(g) + 7O2(g) ----------> 4CO2(g) + 6H2O(l)
DHrex = DHf products -DHf reactants
= 6*-285.8+4*-393.5-(2*-84.7 + 7*0) = -3119.4KJ
e. 2C2H6(g) + 7O2(g) ----------> 4CO2(g) + 6H2O(l)
DHrex = DHf products -DHf reactants
-3119.4 = 4*-393.5+6*-285.8-2*DHf C2H6
-3119.4 = -3288.8-2*DHf C2H6
-2*DHf C2H6 = -3119.4+3288.8
DHf C2H6 = 84.7KJ >>>answer
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