Does Helium Expands Faster than Air When Heated?

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In summary: Based on what you have concluded, Helium will absorb energy faster than air, which will cause the piston cylinder system to expand faster.
  • #1
said_alyami
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This is a really confusing issue .. even when asked my professor in thermodynamics he tried to derive many theromdynamic equations and could not come to a conclusion about it

if we have two cylinder piston systems ,, they both have the exact same conditions except the kind of gas in each one ,,, one has Helium as the working gas ,, the other one has air as the working gas

both cylinder piston systems have the same initial vloume V1 and the same initial Pressure= 1 atm .. and the same initial Temperature= 25 C

then we expose both systems to exactly the same source of heat with exact condition, and both systems starts to have volume expansion that drive the piston up ,, while keeping constant pressure.

its known that Cp for Helium is about 5 times greater than Cp for air ,, and also the thermal conductivity of Helium is much greater than that of air.

my question is : is the piston cylinder system that contains Helium going to expand FASTER than that which contains air? or they both are going to expand at the same speed?

Thank You
 
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  • #2
When you say "faster" I'm guessing that you mean change in volume per unit time.

I don't think Cp for helium is 5 times greater than for air (probably 1.2 times or so) but Helium will probably expand faster because it will absorb energy faster from the reservoir. Rate of heat is quicker into the cylinder with helium, thus it supplies more energy per unit time.
 
  • #3
Curl said:
When you say "faster" I'm guessing that you mean change in volume per unit time.

I don't think Cp for helium is 5 times greater than for air (probably 1.2 times or so) but Helium will probably expand faster because it will absorb energy faster from the reservoir. Rate of heat is quicker into the cylinder with helium, thus it supplies more energy per unit time.

thank you for your reply ,, but based on what you have concluded that Helium will absorb energy faster than air?

Note: yes, faster means: higher chanage in volume per unit time

thanks
 

1. Does helium expand faster than air when heated?

Yes, helium expands faster than air when heated. This is because helium has a lower atomic weight and is less dense than air, which allows it to expand more easily when heated.

2. Why does helium expand faster than air when heated?

Helium has a lower atomic weight and is less dense than air, which allows it to expand more easily when heated. This is due to the fact that the particles in helium are more spread out and have less mass compared to the particles in air, making them more susceptible to changes in temperature.

3. Is there a difference in how helium and air expand when heated?

Yes, there is a difference in how helium and air expand when heated. Helium expands more quickly and to a greater extent than air due to its lower atomic weight and density. This means that the volume of helium will increase more rapidly and to a greater degree than the volume of air when exposed to heat.

4. Can helium and air expand at the same rate when heated?

No, helium and air cannot expand at the same rate when heated. As mentioned previously, helium has a lower atomic weight and density than air, which causes it to expand more quickly and to a greater extent when heated. This difference in expansion rates is due to the differences in the properties of the two gases.

5. How does the expansion of helium and air differ at different temperatures?

The expansion of helium and air differs at different temperatures due to their different properties. Helium will always expand more quickly and to a greater extent than air when heated, regardless of the temperature. This is because the properties of the gases are constant, meaning that the difference in their expansion rates will also remain constant at different temperatures.

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