Avogagro's number

Jurriaan Bendien bendien at tomaatnet.nl
Tue Jul 15 18:05:11 MDT 2003


Yep, Les, I am figuring out this item of terminology, thanks to the
Internet. Sincere thanks for the idea, I must give up smoking cigarettes !

Jurriaan

What is a mole?

Definition: The number of carbon atoms contained in 12.011-g carbon is 1
mole (1 mol), which is 6.02 ´ 1023 atoms and is called the Avogagro's
number. (C-12 is used for defining amu.)
Or a more "general definition" as in the textbook as "The number of atoms
(or formula units or molecules) contained in the atomic mass in g (or
formula mass in g) of an element (or a compound)".

Molar mass: mass in g of 1 mol of the substance

Examples (see more on Table 4.1)
a) water, 18 g/mol (2 mol H + 1 mol O = 2 g + 16 g), or mol/18 g
    2 mol H atoms react with 1 mol O atoms to give 1 mol water molecules
    (But, remember "all gases are diatomic, except noble gases." Thus,
instead of having 2H + O ® H2O, you MUST write 2H2 + O2 ® 2H2O.)

b) CO2, 44 g/mol (1 mol C + 2 mol O = 12 g + 16 g ´ 2), or mol/44 g
    1 mol C reacts with 2 mol O (1 mol O2) to give 1 mol CO2;

c) A small size protein with ~100 amino acids, ~10,000 g/mol.

The "larger" the molecule, the more the mass is in a mole of the molecule

From: http://chuma.cas.usf.edu/~ming/courses/chm2030/lectures/Chap_4.htm








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