0.22 litre of an idealmonatomic gas (Cv = 3R/2) initially at 12 deg C and 1.7 at
ID: 690113 • Letter: 0
Question
0.22 litre of an idealmonatomic gas (Cv = 3R/2) initially at 12 deg C and 1.7 atmpressure undergo an expansion against a constant external pressureof 1.01 atm, and do 2.3 kJ of work. The final pressure of the gasis 1.01 atm. Calculate the change in enthalpy, Delta H.Imnot too sure how to go about this question. I know you cancalculate the final volume and therefore the work but after that imnot sure how to get my numbers into the delta Hequation:
delta H = nCdT
Imnot too sure how to go about this question. I know you cancalculate the final volume and therefore the work but after that imnot sure how to get my numbers into the delta Hequation:
delta H = nCdT
Explanation / Answer
Work = P*(V2 - V1) = 2.3 kJ = 1.01 atm*(V2 - 0.22L) V2 = 0.22L + 2.3 kJ/1.01 atm *(1000 J/1kJ)*(1 atm / 101325Pa)*(1000L/1m3) V2 = 22.6944902 L V1/T1 = V2/T2 T2 = (V2/V1)*(T1) = (22.69 L/0.22L)*(12 + 273)K = 29399.6805 K n = P1*V1/RT1 = (1.01 atm*0.22L)/(0.0821 L*atm/mol/K * 285 K) =0.00949633524 moles delH =n*Cp*T Cp = 5R/2 for monatomic ideal gas delH = 0.00949633524 moles*(5*8.314 J/mol/K / 2)*(29399.6805 K -285 K) delH = 5746.6943 J delH = 5.8 kJ
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.