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Unit 1 ­ Amount of Substance




Formula of Ionic Compounds

H+ Ba2+ Fe3+ Cl- O2-
Na+ Ca2+ Al3+ Br- S2-
Ag+ Cu2+ F- SO42-
K+ Mg2+ I- CO32-
Li+ Zn2+ HCO3-
NH4+ Pb2+ OH-
Fe2+ NO3-
H-


Relative atomic Mass (Ar)
The weighted average mass of an element, taking into…

Page 2

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Unit 1 ­ Amount of Substance




Molecular Formula
Gives us the actual number of each type of atom in a molecule

Empirical Formula
The formula used to represent the simplest ration (by mole) of atoms in a compound.

Finding Empirical Formula

Element A B
Mass (g) a X
Mass of…

Page 3

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Unit 1 ­ Amount of Substance




p = pressure (Pa)
V= volume (m3)
n= number of moles
R= gas constant = 8.31
T=temperature (kelvins)

pressure
1 kPa=1000Pa
kPa x 1000 = Pa

volume
1m3 = 1000 dm3 = 1,000,000 cm3
cm3 / 1,000,000 = m3
dm3 /1000 = m3
m3x…

Page 4

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Unit 1 ­ Amount of Substance




step one ­ balance equation
step two ­ use mass or conc X vol(dm3) to find the number of moles in the first substance
Mr
step three ­ use ration from the equation to find the number of moles in the other substance
step…

Page 5

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Unit 1 ­ Amount of Substance




You can then work out a percentage yield using
Percentage Yield = actual yield .
Theoretical yield

Reasons why a yield may be low:
Reaction may be incomplete (perhaps it is slow, or reaches equilibrium state) so a portion of
the starting chemicals fail…

Page 6

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Unit 1 ­ Amount of Substance




The number of significant figure of the result should be equal to that of the quantity that
contains the least number of significant figures.

In General
The uncertainty in a single measurement from an instrument is half the value of the smallest
division.

For…

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