3.1.2 Amount of Substance Flashcards
Relative atomic mass (Ar)
The average mass of an atom of an element compared to 1/12 the mass of a carbon-12 atom, taking into account relative abundance of isotopes
Relative molecular mass (Mr)
The average mass of a molecule of a compound compared to 1/12 the mass of a carbon-12 atom
Relative formula mass
The average mass of an ionic compound compared to 1/12 the mass of a carbon-12 atom
What is Avogadro’s constant
6.02x10^23 - the number of particles in a mole
Mole equations
Moles = Mass/Mr
Moles = concentration x volume
Ideal gas equation + units
pV = nRT
p - Pa
V - m3
n - mol
R - 8.31
T - K
Empirical formula
The simplest whole number ratio of atoms of each element in a compound.
Molecular formula
The actual number of atoms of each element in a compound.
Percentage yield equation
(Experimental mass / Theoretical mass) x 100
Percentage atom economy equation
(Mr of desired product / Mr or reactants) x 100
Why is high atom economy good
- Little waste produced
- Less energy needed
- More economically viable
- Uses less natural resources
How to calculate empirical formula with percentages
Divide percentage by Ar of each element in the compound, then find simplest whole number ration
Why don’t actual and theoretical yield match up
Chemicals lost on apparatus
May be gaseous and lost to environment
