Is a mole (mol) a base unit or a dimensionless quantity?

Mullah.S

Is confusion to me. :confused:

Reply 1

charco

Study Forum Helper

Original post by Mullah.S

Is confusion to me. :confused:

According to SI it is a base (fundamental) unit

http://en.wikipedia.org/wiki/SI_base_unit

Reply 2

username913907

A mole is just a number. It is the number of molecules that is equal in mass (in grams) to it's relative molecular mass.
e.g. 1 mole of 12C (carbon-12 isotope) atoms is equal to 12 grams.

This number is known as Avagadro's constant.

Reply 3

charco

Study Forum Helper

Original post by JMaydom

JMaydom!!!!!

(edit)

Lorenzo Romano Amedeo Carlo Avogadro di Quaregna e di Cerreto would turn in his grave ....

(edited 11 years ago)

Reply 4

charco

Study Forum Helper

Original post by Mullah.S

Is sounding like mere mark scoring definition, i am wanting know whether is dimensionless quantity or a base unit.

thank you anyway

I wrote that it is a base unit in my post above!

Reply 5

natninja

Original post by Mullah.S

Is confusion to me. :confused:

A mole is an SI unit I think, definitely has dimensions.

(edited 11 years ago)

Reply 6

Mullah.S

Original post by charco

According to SI it is a base (fundamental) unit

http://en.wikipedia.org/wiki/SI_base_unit

ok thanks.

But my question is being, if is base unit and not dimensionless quantity, is meaning it is having dimension. What is the dimension of the base unit mole? (i.e what is the base quantity)

Original post by charco

I wrote that it is a base unit in my post above!

oh i am seeing only know, thankyou

Original post by charco

JMaydom!!!!!

Amedeus would turn in his grave ....

Amedeo*

to much mozart

(edited 11 years ago)

Reply 7

The_Last_Melon

It's just an amount of something.

Reply 8

Mullah.S

Original post by The_Last_Melon

It's just an amount of something.

what does amount meaning if it is not dimensionless quantity?

(edited 11 years ago)

Reply 9

The_Last_Melon

Original post by Mullah.S

what does amount meaning if it is not dimensionless quantity?

moles is a dimension just like metres, yards, litres and volts are. just remember n moles is equivalent to n*6.0221415e+23 molecules. i think they use it because it's much more useful to know than litres which is the amount of space the substance takes up which is very dependant on intermolecular forces and greatly varies depending on the molecule.

i only did AS chemistry though so take my advice with a pinch of salt

EDIT: also two more things to remember:

1 mole of any substance has a mass equal to the molecular mass of that substance in grams. so 1 mole of carbon (molecular mass 12) has a mass of 12g, 1 mole of CO2 has a mass equal to the molecular mass of carbon + 2* the molecular mass of oxygen in grams.

also I think but i'm not sure that a mole of any gas has the same volume as a mole of any other gas. need someone to confirm this though.

(edited 11 years ago)

Reply 10

User1014865

It's just a standard unit of measurement. It just lets scientist know how many atoms are in something (usually a solution). It isn't dimensionless, a mole can physically be measured.

Best way to think about it:
There are 6.023 x 10^23 atoms in 1g of hydrogen. Carbon is 12 times heavier than hydrogen so 6.023 x 10^23 atoms in carbon will be 12g. If hydrogen is the standard, the number of grams in a mole of any element can be figured out (14g of nitrogen makes a mole, 16g of oxygen makes a mole etc...)

Reply 11

Mullah.S

Original post by Iamyourfather

Oh, i am thankyou.

i was thinking mole is just synonym of avagadro number (which is a dimensionless quantity). so one mole of a thing does not meaning 6.02*10^23 of the things.

Reply 12

username913907

Original post by charco

JMaydom!!!!!

(edit)

Lorenzo Romano Amedeo Carlo Avogadro di Quaregna e di Cerreto would turn in his grave ....

grrrrr

Cracking full name...

Reply 13

User1014865

Original post by Mullah.S

Oh, i am thankyou.

i was thinking mole is just synonym of avagadro number (which is a dimensionless quantity). so one mole of a thing does not meaning 6.02*10^23 of the things.

Thb, I wasn't entirely sure what you meant by 'dimensionless'.
Based on what was said just know that 6.022x10^23 (ignore the number I write earlier) atoms is mole.

Reply 14

holliebass

I think it might be dimensionless as a "mole" of something is just 6.02 x 10^-23 of something, it's just a number. And I think it is therefore dimensionless as it's just a number of things.

Like one mole of electrons is 6.02 x 10^-23 electrons, and one mole of hedgehogs is just 6.02 x 10^-23 hedgehogs... It is a SI unit but I believe it is also dimensionless, so it's both.

(edited 11 years ago)

Reply 15

Mullah.S

Original post by holliebass

unit and dimensionless are be mutually exclusive

is like saying something is both haraam and halaal at the same time

Reply 16

holliebass

Original post by Mullah.S

unit and dimensionless are be mutually exclusive

is like saying something is both haraam and halaal at the same time

Yeah I was wrong:

"According to the SI, the mole is not dimensionless, but has its very own dimensions, namely "amount of substance", comparable to other dimensions such as mass and luminous intensity"