Amount of substance

Includes all of the unit 2 calculations 

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Amount of Substance
Relative Atomic and Relative Molecular Mass
Atomic (Ar) ­ Average mass of an atom/element
mass of one atom of C12
Molecular (Mr) ­ Average mass of a molecule
mass of one atom of C12
Moles and Avogadro's Constant
A mole is the number of particles, the number of moles can be calculated by using the following
equation/triangle. This can also be used to calculate the mass (in grams) and the Mr of a compound.
Avogadro's Constant
The definition of the Avogadro's Constant/Avogadro's Number is the number of atoms in 12g of Carbom-12.
Avogadro's Number = 6.02 x 1023 ­
Concentration of Solutions
The following equation is used for titration calculations and can be used to calculate the
volume (dm3 ), concentration or moles.
Units of Volume
1 cm3
1/1000 dm3
1 litre 1dm 3
1 ml
1/1000 dm3
Empirical Formula
This is the ratio of elements that are present in the compound in the simplest form:

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Molecular Formula
This is the total number of atoms of each element in each molecule of a substance:
1. Take the empirical formula and Mr that is given
Mr: 78
2. Calculate the sum of the Mr
(12 + 1)n = 78
3.…read more

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Mass/Mr of all products
Ionic Equations
This takes an equation and writes it in terms of ions, for example:
CuSO4 (aq)+ 2NaOH (aq) Na
2SO 4 (aq)+ Ca(OH)2 (s)
1. Rewrite the equation with the ions. Solids cannot be written in terms of ions
2- + + 2-
Cu2+ + SO4 + 2Na + 2OH -
2Na + SO 4 + Cu(OH)2
2. Remove the ions that are the same from each side
+ 2OH- Cu(OH) 2
Percentage Error
Balances: + /-0.…read more



Thank you so much for sharing these, incredibly helpful! **

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