Thermochem, thermodynamics, diatomic gas at constant volume

[Diamond101]

Homework Statement

A sample consisting of one mole of a diatomic perfect gas is heated from 25 °C to 200 °C at constant volume. Calculate q, w, ΔU and ΔH for the process, given that Cv = 23.02 J K-1 mol-1 .

Homework Equations

Im studying for mid terms and i have no lecture notes on diatomic gas looking online currently haven't found much. Please explain

The Attempt at a Solution

du=w-cvdt
cv=5/2nr

 

[Chestermiller]

Homework Statement

A sample consisting of one mole of a diatomic perfect gas is heated from 25 °C to 200 °C at constant volume. Calculate q, w, ΔU and ΔH for the process, given that Cv = 23.02 J K-1 mol-1 .

Homework Equations

Im studying for mid terms and i have no lecture notes on diatomic gas looking online currently haven't found much. Please explain

The Attempt at a Solution

du=w-cvdt
cv=5/2nr

You don't need to know what a diatomic gas is to solve this problem. They give you the value of the heat capacity. That's all you need.

If the volume of gas is constant, how much work is done?

What is that Cv doing that equation that you wrote? The equation is incorrect. It should read ΔU=Q-W

 

[Diamond101]

wont it be du=q+w
w=-pdv
du=q-pdv
du=qv at const volume .

 

[Diamond101]

You don't need to know what a diatomic gas is to solve this problem. They give you the value of the heat capacity. That's all you need.

If the volume of gas is constant, how much work is done?

What is that Cv doing that equation that you wrote? The equation is incorrect. It should read ΔU=Q-W

how do i find work , work it -pdv right? i wasnt given pressure or is it understood as 1 bar and i wasnt given a volume

 

[Chestermiller]

how do i find work , work it -pdv right? i wasnt given pressure or is it understood as 1 bar and i wasnt given a volume

If the volume doesn't change, what is dv equal to?

 

[Diamond101]

If the volume doesn't change, what is dv equal to?

0, and because w=pdv no work is done ? is this an isochoric process? would du=n cvdt

 

[Chestermiller]

0, and because w=pdv no work is done ? is this an isochoric process? would du=n cvdt

Very nice. Yes. isochoric is synonymous with constant volume. And your equation for the differential change in internal energy is correct.

Chet

 

[Diamond101]

i figured it out i got 4.028 kj
w=0
du=q+w
du=Q
q+du are the same
dh=du +pdv
q=ncvdt

 

[Diamond101]

Very nice. Yes. isochoric is synonymous with constant volume. And your equation for the differential change in internal energy is correct.

Chet

thank you ever so much