4. WALT
To be able to understand the importance of
chemical reactions and empirical formulae.
To be able to state the reactants and products of a
chemical reaction by using an analogy. Grade D
To be able to make a compound and describe how to
calculate the Empirical Formulae of a Copper Sulphate.
Grade C
To be able to calculate the Empirical Formulae using your
knowledge for other known compounds. Grade B/A
WILF
6. Success criteria for GCSE
Risk Assessment
GRADE A GRADE B GRADE C GRADE D
As B and
references
made to
secondary
resources
As C and
precautions
detailed in
full to reduce
incidence of
harm
Risk
Identified
and described
in terms of
appropriate
action.
Some
precaution
noted
Some risk
identified but
gaps evident
and missing
information in
relation to
action needed
8. Equipment Check list
Making your
chemical
• Safety goggles
• Beaker
• Measuring
cylinder
• Spatula
• Copper Oxide
• Sulphuric Acid
Filtering
• Conical Flask
• Funnel
• Filter paper
Evaporating
• Evaporating
Basin
9.
10.
11.
12. • The empirical formula is the simplest ratio of
the different atoms in it. For example for
ethane it is CH3.
• You can work out the empirical formula of a
compound if you know the mass of each
element in it.
• This is the reverse of finding out the % mass of
a compound from its formula.
13. Example: What is the empirical formula of a
compound that contains 27.3% carbon and
72.7% oxygen by mass?
• Step 1 Find, and write down the relative atomic masses of
the elements involved.
• Ar (C) = 12 and Ar (O) = 16
• Step 2 Assume that you have 100g of the compound (this
makes the maths easy).
• In 100g there is 27.3g of carbon and 72.7g of oxygen
14. • Step 3 Work out how many moles of each element
this must be using
number of moles =Ar__
mass
• number of moles of carbon= 27.3 =2.275
12
• number of moles of oxygen = 72.7=4.55
16
15. • Step 4 Divide both numbers of moles by the smallest
number (2.275 in this case).
• number of moles of carbon = 2.275=1
2.275
• = number of moles of oxygen = 4.55 =2
2.275
In the empirical formula, there are 1 carbon atom
and 2 oxygen atoms, so it is CO2.
16. Copper Sulphate
Calculating Empirical Formula
What is the empirical formula of a
Copper Sulphate that contains
........% carbon, Sulphur ........%
and .........% oxygen?
17. WALT
To be able to understand the importance of
chemical reactions and empirical formulae.
To be able to state the reactants and products of a
chemical reaction by using an analogy. Grade D
To be able to make a compound and describe how to
calculate the Empirical Formulae of a Copper Sulphate.
Grade C
To be able to calculate the Empirical Formulae using your
knowledge for other known compounds. Grade B/A
WILF
21. WALT
To be able to understand the importance of
chemical reactions and empirical formulae.
To be able to state the reactants and products of a
chemical reaction by using an analogy. Grade D
To be able to make a compound and describe how to
calculate the Empirical Formulae of a Copper Sulphate.
Grade C
To be able to calculate the Empirical Formulae using your
knowledge for other known compounds. Grade B/A
WILF
