How can the density of air be measured using simple equipment?

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Homework Help Overview

The discussion revolves around measuring the density of air at normal atmospheric pressure using simple equipment, including scales, glass bottles, water, and a vacuum pump. Participants explore the feasibility of the proposed method and the underlying principles of density and buoyancy.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss measuring the volume of the bottles using water displacement and weighing the air inside them to calculate density. There are questions about the simplicity of the method and the accuracy of measuring small masses of air.

Discussion Status

Some participants express concern about the simplicity of the approach, while others suggest that it may still yield a rough estimate of air density. There is acknowledgment that the method could work, but no consensus on its effectiveness has been reached.

Contextual Notes

Participants note the limitations of available equipment and the challenges of measuring small masses accurately. There is a discussion about the assumptions involved in the calculations and the potential for error in the measurements.

Alettix
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Homework Statement


Measure the density if air at normal atmospheric pressure. You can use the following equipment:

One scale with an accuracy of 0.01g
Two empty glas bottles (≈0,33 liter each)
One big bowl with water
One cork with a valve and a vacuumpump

Homework Equations


Not knowing how to solve this problem I am not sure which equations should be used, but the following could be relevant:
Density: ρ=m/V (1)
Ideal Gas equation: pV=nRT =NkT (2)
Buoyant Force: F=ρgV (3)

The Attempt at a Solution


My first thought was that the exact volume of the bottles can be measured by measuring the weight of the water which fit into them and then by knowing the density of water the volume is obtained. Then, we can meausre the weight of an empty bottel with air in it and without. From this, the mass of the air inside the bottles is obtained and the density of the air is achieved. However, I feel like this is a bit to simple. I don't have the equipment to try this at home. Do you think think this solutions works? Or do you have other ideas?

Thank you for your help! :)
 
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Why do you think it is too simple?
 
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Orodruin said:
Why do you think it is too simple?
I thought the mass of the air was too small to be measured, but now I realized that m = 1,293*0,00033 ≈0,43 g.
So maybe this is the solution?
 
Yes, it should be enough to at least give you a quite rough estimate.
 
Orodruin said:
Yes, it should be enough to at least give you a quite rough estimate.

Well, in that case the problem is solved. Thank you very much! :)
 

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