Physics adicabatic question....?

Question

Consider two cylinders of gas identical in all respect except that one contains o2 and the other He. Both hold the same volume of gas at SP and are closed by a movable piston at one end. Both gases are now compressed adiabatically to one-third their original volume. Which gas wil show the greater temperature increase?

a)O2
b)He c)neither; both same increase
d)not enough information...

using pv=nrt or w=pdeltav...

p.s. the answer is He

can i have an explanation why the answer is b or how to get to b??
lol..

Answer 1

There's a fair amount of thermodynamics and physical chemistry in this question.

Since each cylinder has the same volume and initial conditions, both have the same number of moles (or molecules) of gas

Begin by assuking that when you compress the gases, the amount of work done on each cylinder is the same . If both cylinders ended up at the same temperature this woul dbe true because of the ideal gas law. If one cylinder ends up at a higher temperature then more work would be done on that cylinder since the final temperature (and thus pressure) is higher.

It is a basic concept of thermodynamics that the internal energy of an ideal gas is a function of temperature and not of pressure or volume. So the compression work done on the cylinders increases the internal energy by the amount of work done.

This increase in internal energy shows up as a temperature rise. Work (Q) is related to temperature rise (DT) through the molar heat capacity (Cp):

Q = n*Cp*DT

So fo the same work done (or equivalently heat added), the gas with the lower specific heat will have a greater temperature rise.

At this point you can just look up the specific heats of the two gases or take the physical chemistry approach. The specific heat of a gas is a function of the number of degrees of freedom of the molecule. The more degrees of vibrational freedom, the higher the specific heat. Helium, being monatomic only has translational degrees of freedom. There are no vibration modes. Oxygen is diatomic and thus has additional vibrational degrees of freedom. Therefore helium has the lower specific heat and will exhibit a higher temperature rise.

In the very start I assumed that both cylinders ended up at the same temperature so the work input is the same. Since the helium has a higher temperature for the same amount of work, it requires even more work to compress it so the difference in temperature rise is actually greater than the specific heats ratio of the two gases.

Answer 2

1) try using the law of the adiabatic transformation:
PV^g =cte
where g is the adiabatic coefficient of the gas
2) the law of perfect gases
PV=nRT

unless specified differently the thermodinamics problems assume the gases involved behave like perfect gases.

Answer 3

basically extra physics jargon ... i'm no longer even specific if it is authentic anymore ... Photons and gluons are strictly massless. they're the gauge fields of unbroken symmetries (no longer in basic terms like the susceptible vector bosons). because of the solid tension and the self-interactions of the gluons (the solid tension originates from a non-Abelian team -- so there is self interplay between the gauge fields -- the gauge fields themselves are charged), there may be gluon condensation and the condensation looks great. As they're massless, they do no longer immediately work together with Higgs boson on the tree-point. At larger-loop tiers, there are interactions on account which you may have each and every style of digital debris (i.e. debris that are no longer 'on-shell'). the comparable in all probability is going for the interactions with gravitons (the particle interpretation of the gravitational container). Photons curve around great bodies. Photons can no longer escape black holes while they're interior the form horizon of the black holes. even if if, those 2 issues are particularly self reliant, except the curvature of the photon trajectory is triggered by potential of the black hollow.

Answer 4

Your original question states that the answer is b. You did not ask for an explanation of the answer. This means you did not actually ask a question.

Answer 5

Answer is a:O2

Because the pressure is same because oxygen molecule has bigger volume than hydrogen