Does temperature affect mass?

[TheShapeOfTime]

I asked this question in the physics (http://www.physicsforums.com/showthread.php?t=50722) general forum and didn't get a solid answer. They say temperature won't really matter here, so what would be a reason to let the substance cool, from a chemistry point of view?

[altered-gravity]

I asked this question in the physics (http://www.physicsforums.com/showthread.php?t=50722) general forum and didn't get a solid answer. They say temperature won't really matter here, so what would be a reason to let the substance cool, from a chemistry point of view?

Hi,
Don´t get surprised about it.

It´s just a problem of convection flux in air. If the sample is hot, the air surrounding it is warmed and it starts going upwards. Due to the non-zero viscosity of the air this can lead into an ascending force in the sample, altering the measure.

[slepsta]

Temperature does not affect mass but it does effect the instrument measuring mass. Analytical balances are calibrated at room temperature.

[altered-gravity]

Perhaps in your case the reason is to avoid the sample reabsorbing water (hot things that are getting cooled tend to absorb water). And you´re working with an higroscopic salt, so the cooling must be done in dry atmosphere before measuring.

[TheShapeOfTime]

Thanks for your replies!