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Does anyone know how to calculate the values for step two of Pathway One? Neither V nor P are constant!
-- Anonymous, February 04, 2000
Hey! wow, Tara and I had the same problem...we couldn't do the problem because of that part. If anyone could provide an answer that would be really great. thanks!
-- Anonymous, February 04, 2000
For step two you can use the values they give of P and V to find the temperature for each set of data by using PV = nRT. These two values of Temperature allow you to subtract them and find the change in temperature for step two. Knowing change in Temp allows you to find delta H and delta E, but I still don't know how to get q or w.
-- Anonymous, February 05, 2000
How did you obtain deltaE or deltaH by using this method??? I know how to obtain for this part: -you know that w=-p*deltaV. well, in this case, the pressure is going to be the value 6 based on the assumption given in the problem. -next to obtain deltaV you must subtract 55 from 20 to give a value of -35. -to multiply -p and delta V gives a total of 210L*atm. -convert this over to Joules or kJoules. -your final value for work should equal 21.3kJ or 21273J
-- Anonymous, February 05, 2000
Why do we use p=6 atm rather than p= 6atm-3atm (the change in pressure from pathway 1 to pathway 2) in Pathway 2 of Problem #27?
-- Anonymous, February 06, 2000
To simplify typing delta = d Liz is right using the idael gas law:dT = C*d(PV)/ nR d(PV) = ((P2*V2) - (P1*V1)) P2 = the second pressure
Then for pathway 1 step 2: dE = n*(Speciic heat)*dT
-- Anonymous, February 06, 2000
Sorry ignore what I just wrote in the previous answer I acidently summited before I was ready. The following is correct.To simplify typing delta = d
Liz is right using the ideal gas law: dT = d(PV)/nR
also useful for this problem d(PV) = ((P2*V2) - (P1*V1)); where P2 = the second pressure, ect.
Then for pathway 1 step 2: dE = n*(Specific heat(Cv))*dT = n*(3R/2)*(d(PV)/nR) = (3/2)*d(PV)
dH = n*(Specific heat(Cp))*dT = n8(5R/2)*(d(PV/nR) = (5/2)*d(PV)
It says in the problem to assume external pressure is constant and equal to final pressure. Therefore, for this step external pressure = Pext = 6atm.
w = -Pext*dV
Then to find q:
dE = q + w q = dE - w
-- Anonymous, February 06, 2000