Recent content by ky92

thank you! let me think about it...

for an adiabatic process, Q=0, ΔU=w+0=w w=ΔU=CvΔT... that's all i can think of i have no idea lol

Homework Statement Consider a system consisting of 2.0 mol CO2 (assumed to be a perfect gas) at 298K confined to a cylinder of cross-section 10cm^2 at 10 atm. The gas is allowed to expand adiabatically and reversibly against a constant pressure of 1 atm. Calculate W, Q, ΔU, ΔH, and ΔT when the...

oh this really helps me a lot thank you!

thx! do u mean that ΔH=CpΔT even in an isochoric process?? so, for an isothermal process, ΔH=CpΔT = 0 for an isochoric process, ΔH=CpΔT for an isobaric process, ΔH = Q= ΔU+Δ(PV)=CpΔT in reversible isobaric process am i correct? oh my god so confusing

why would the model use ΔH = CpΔT if it is not an isobaric process? i thought q=CvΔT and ΔH=q=CpΔT in isobaric process!

hey could anyone help?

i see! thanks a lot and could anyone answer my first question posted above...thanks

why Q=ΔU+W i know ΔU=q+w and it should be q=ΔU-w

thank you karkas. actually you remind me of another question, for isothermal process, ΔT=ΔU=0 ΔH = ΔU + Δ(PV) = ΔU + Δ(nRT) = 0+0 = 0 so for isothermal process, heat is not necessarily be zero but ΔH is always zero, while an adiabatic process, heat must be zero while ΔH can be nonzero, am i...

Homework Statement A sample of 3 mol of a diatomic perfect gas at 200K is compressed reversibly and adiabatically until its temperature reaches 250K. Given that Cv,m=27.5 JK-1mol-1, calculate q, w, ΔU, ΔH and ΔS. Homework Equations dS = dq/T ΔU = n(Cv,m)ΔT ΔH = n(Cp,m)ΔT The...

oh i get it now it's just because we assume the reaction is an isobaric, then isothermal process so T is constant for the second part i.e. in nR ln(V2/V1) thanks! you help me a lot i am bad in physics :P

thank you! by the way why couldn't i replace (V2/V1) by (T2/T1) in this case? (but we can replace V2/V1 by P1/P2) i don't really get it! how to decide whether we should substitute between P-V or P-T/V-T?

Homework Statement calculate the change of entropy (for the system) when 3 moles of a monatomic perfect gas, for which Cp,m = (5/2) R, is heated and compressed from 298K and 1atm to 398K and 5atm. ans: -22.1 JK-1 Homework Equations for an ideal gas, Pv=nRT for iso-choric condition...