How Does Temperature Affect the Density of Helium Gas?

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Homework Help Overview

The discussion revolves around the effect of temperature on the density of helium gas, specifically analyzing a scenario where the temperature is increased from 0°C to 105°C while maintaining constant pressure. The context is rooted in the ideal gas law and the properties of gases.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the setup of the problem using the ideal gas law, questioning how to calculate the new density based on temperature changes. There are attempts to clarify the relationship between temperature, pressure, and density, with some participants exploring the calculations for volume and density at standard conditions.

Discussion Status

The discussion is ongoing, with participants seeking clarification on specific values used in calculations, such as the gas constant R. Some guidance has been provided regarding the calculations needed to determine the new density, but no consensus has been reached on the approach or the values to use.

Contextual Notes

Participants are working under the assumption that helium behaves as an ideal gas and are referencing standard conditions for their calculations. There is some confusion regarding the appropriate value of the gas constant R, indicating a need for further clarification on unit conversions.

BunDa4Th
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Homework Statement



The density of helium gas at T = 0°C and atmospheric pressure is 0 = 0.179 kg/m3. The temperature is then raised to T = 105°C, but the pressure is kept constant. Assuming that helium is an ideal gas, calculate the new density f of the gas. kg/m3

Homework Equations



PV = nRT
m/v = weight in grams?

The Attempt at a Solution



T1 = 0*C T2 = 105*C
Po = .179 Pf = ?
Pa1 = 1 atm? Pa2 = 10 atm?

I think that is how I am suppose to set it up but from there I am at a complete lost on what to do. But i am not even sure where to start on this problem.
 
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BunDa4Th said:

Homework Statement



The density of helium gas at T = 0°C and atmospheric pressure is 0 = 0.179 kg/m3. The temperature is then raised to T = 105°C, but the pressure is kept constant. Assuming that helium is an ideal gas, calculate the new density f of the gas. kg/m3

Homework Equations



PV = nRT
m/v = weight in grams?

The Attempt at a Solution



T1 = 0*C T2 = 105*C
Po = .179 Pf = ?
Pa1 = 1 atm? Pa2 = 10 atm?

I think that is how I am suppose to set it up but from there I am at a complete lost on what to do. But i am not even sure where to start on this problem.
The key here is to find the volume change per unit mass.

They give you the density of He at STP. But let's calculate it. Assume you have one mole of gas. Calculate the volume of one mole at 273K (0 C) and 1 atm (101325 Pa) using the Ideal gas law:

V = nRT/P = 1*8.314*273/101325 = .0224 m^3 = 22.4 L

Since one mole of He has mass of 4g, the density is .004/.0224 = .179 kg/m^3.

Do the same for He at a pressure of 378K (105C) and 10 atm. That is all the question is asking.

AM
 
I have a question on how did you get R to equal to 8.314?

I thought R would be .0831 or am i looking at a different R value?
 
BunDa4Th said:
I have a question on how did you get R to equal to 8.314?

I thought R would be .0831 or am i looking at a different R value?
In MKS:

R = N_A k_B = 8.31451 m^2kg/s^2 K mol

The .0831 must be in units of m^2kg/s^2 K mol \times 10^3 or kilomoles

AM
 
Last edited:

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