Okay, this is probably a really stupid question, but lacking a scale, one I can’t check myself. If you take one pound of coffee beans and grind it up, do you wind up with one pound of grounds, or does the molecular change of the bean result in a weight difference? It sure feels lighter…
Molecular change of the bean? Eh? You finally find the long-sought Philosopher’s Stone and usin’ to grind beans?
Why would grinding cause molecular change?
The only weight difference comes from the very small amount of bean left in the grinder.
It’s probably not even noticable on most kitchen scales.
Jeez, ya use one big word wrong and ya get a world of crap… :smack:
I meant the physical change the bean goes through in the course of being ground up from a single solid into hundreds of tiny solids.
Does slicing a whole pizza into 6 slices change the amount of pizza you have?
And after you’ve used the grinder a few times, there’s not even that. Every place where the residue can get trapped is already filled. Unless you’re cleaning it out after every use.
A pound is a pound the world around, right?
You think these comments are a “world of crap”? Check out the thread I started for you in The Pit.
Kidding 
What weighs more: a ton of bricks or a ton of feathers? 
You better cut the pizza in four pieces because I’m not hungry enough to eat six. -Yogi Berra
[splitting hairs]Once the bean is cracked, though, its surface area is increased, and places that were once bonded to other parts of the bean are now able to react with the air. Might this increase/decrease the mass? Also, a ground bean is more aromatic; our ability to sense the smell is really volatile molecules leaving the bean and entering our noses. Surely these compounds leaving the grounds reduce the mass by a tiny amount…[/splitting hairs]
I think the point we’re shooting towards is this: Whole beans have more air by volume separating them than grounds do, i.e., if a pound of coffee beans is, say, five cups, is a pound of grounds only four cups because the grounds have less dead air space between them?
Aaaaaaaand the increased surface area of the dried powder will be absorbing a lot of of moisture from the air.
The DENSITY will most certainly be higher, but as the volume of substance will decrease, there would be no net gain/loss for this factor alone.
I think you mean lower. A lb of ground beans will take up more volume than a lb (or kg) of intact beans. If the volume inceases, and the mass (weight) stays the same, the density decreases (density=mass/volume). This is why the OP says “it feels lighter.”
Why would this be true? Packing efficiency is independant of size, so it could only be due to the ground particles being a different shape, and I can’t imagine that they’d be that significantly different.
Packing efficiency is independant of size of uniformly sized object but packing efficiency increases proportionally to the variability of size. You can pack rocks and sand more efficiently than just rocks.
Coffee beans are very uniform in size whereas presumably the grounds are less uniform, leading to more efficient packing. Also, packing theory only applies to rigid objects. I’m willing to be that grounds are significantly less rigid than beans, further increasing density.
huh…In that case I’d like to change my response?
What’s your definition of a ton? Equal mass of brick and feathers might show the feathers lighter on a scale due to bouyancy effects in the air at sea level. If by a ton, you mean “when placed on a scale, reads 1 ton” and if by “weighs” you mean “the value shown when placed on a scale”, then they’re the same by definition.
As to the OP, the act of grinding the beans per se does not change the weight. However, things like adding heat during the grinding process could increase the mass (if you’re a relativist). But loss of grounds in the machine and loss of molecules in the air due to increased surface area are not direct results of the grinding but after-effects.