Why is the concept of amount of substance as a quantity confusing?

[adityatandon]

I never really understand why we should have a 'unit' for a 'count' i.e. the mole. And what is the need of assigning a separate quantity, the amount of substance... we already have 'mass'; don't we ?

P.S. - I mistyped the topic title... It should be "Amount Of Substance as a quantity"

 

[Nick89]

And how do you think mass is a measure of the 'amount of substance'? If you have one kilogram worth of feathers, and one kilogram worth of steel, do you feel the 'amount of substance' is the same?

 

[russ_watters]

The "mole" is only needed if there is some indivisible minimum mass of a substance...

 

[flatmaster]

You need to define a counting number as a unit so that you can convert from a discrete scale "number of molecules" to what appears to be a continuous number "number of kilograms". It completes the step from number, to amount.

 

[adityatandon]

And how do you think mass is a measure of the 'amount of substance'? If you have one kilogram worth of feathers, and one kilogram worth of steel, do you feel the 'amount of substance' is the same?

Err... that depends on how we define 'amount of substance'

You need to define a counting number as a unit so that you can convert from a discrete scale "number of molecules" to what appears to be a continuous number "number of kilograms". It completes the step from number, to amount.

So we have a number (one mole) as a unit ? Appears strange...

 

[russ_watters]

So we have a number (one mole) as a unit ? Appears strange...

Why does it appear strange? You aren't explaining why you are uncomfortable with the concept.

You do understand what atoms and molecules are, right?