# Moles1 The Basics Revision

Revision notes on Moles for AS chemistry.

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• Created on: 02-11-07 12:01

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Moles 1 ­ The Basics Revision Page
Definitions:
Mole: a very large number 6.02 *1023 (Avogadro's Constant). It is a measurement eg a dozen.
Relative Atomic Mass (RAM): the weighted average mass of the atoms of an element in
their natural isotopic abundance, compared to carbon 12.
Relative Molar Mass (RMM): in grams of any molecule contains the same number of
molecules as there are atoms of carbon in12g of carbon 12.
Empirical Formula: the simplest whole number ratio of atoms of each element in a compound.
Molecular Formula: simple multiple of the empirical formula. It gives the correct molar mass.
Compound Working RMM
H2 SO4 (1*2) + 32 + (16*4) 98g/mol
How many atoms in Yg of X? RMMg of
X contains 6.02 *1023 atoms
1g of X contains 6.02 *1023 / RMM atoms
Yg of X contains (6.02 *1023 / RMM) *Y atoms
How many molecules in Yg of X?
RMMg of X contains 6.02 *1023 molecules
1g of X contains 6.02 *1023 / RMM molecules
Yg of X contains (6.02 *1023 / RMM) *Y molecules
How many atoms in 2 moles of X? 6.02 *1023 * 2
How many molecules on 0.5 moles of X? 6.02 *1023 / 2
Empirical Formula: (MMR 128
X Y
Mass
RMM
Moles
/Smallest
Ratio : eg.
C5H4

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RMM empirical formula = 64
n= 128 / 64 = 2