HMCS Max Bernays Pre-Deployment Brief (May 2024).pptx
Chemical Reactions
1. CHEMICAL REACTIONS
1. Describe chemical change in terms of formulae, equations and valency.
2. Recognise oxidation and reduction in terms of electron transfer.
3. Recognise oxidation and reduction in terms of transfer of oxygen and hydrogen.
4. Explain the mechanism of dissolving and explain the formation of a precipitate.
5. Predict the identity of a precipitate in a precipitation reaction.
6. Describe thermal decomposition of metal hydroxides, carbonates and hydrogen
carbonates.
7. Show an understanding of atomic an molecular masses.
8. Calculate percentage composition of compounds.
9. Calculate empirical formulae from data relating to
percentage composition.
10.Calculate mass ratios of chemicals involved in chemical
reactions.
Thursday, 16 September 2010
6. Term Ans Definition GLOSSARY 1 Match the term with its definition > ans’s only in BOB
A. Valency
B. Ion
C. Reactants
D. Products
E. Oxidation
F. Reduction
G. Half -
equation
Thursday, 16 September 2010
7. Term Definition GLOSSARY 1- HANDOUT
A. Ion
B. Precipitate
C. Species
D. Redox 4. a term that describes any oxidation-reduction reaction
Thursday, 16 September 2010
8. Term Ans Definition GLOSSARY 2 Match the term with its definition > ans’s only in BOB
Thursday, 16 September 2010
9. Term Definition GLOSSARY 2- HANDOUT
Thursday, 16 September 2010
10. FORMULAE
AND
EQUATIONS
Thursday, 16 September 2010
12. VALENCY Copy
Valency is a term that allows us to predict how an atom will bond with other atoms.
It is given as a number.
Two ways of thinking about valency:
1. For ionic compounds it is the number of electrons that an atom will gain or
lose in order for it to gain an octet/duet of electrons.
2. For covalent compounds it is the number of bonds that it will form that will
allow it to gain an octet/duet.
Examples
Oxygen, O has a valency of 2. (it will gain two electrons to form an octet when it
forms an ionic compound or share two electrons to form an octet when it forms a
covalent compound)
• MgO (the Oxygen atom has a 2- charge in this compound)
• CO2 (Each O atom has formed 2 bonds with carbon in this compound)
Repeat the above illustration for Phosphorus. Use Phosphorus trichloride and Sodium
phosphide as the compounds
ESA: p61 - 63 Ex 8A
Thursday, 16 September 2010
13. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
Sodium Fluoride _____________ Magnesium Oxide __________
Sodium Oxide _______________ Zinc Chloride _____________
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
THE PROCESS FOR WRITING FORMULAE
Thursday, 16 September 2010
14. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
Sodium Fluoride _____________ Magnesium Oxide __________
Sodium Oxide _______________ Zinc Chloride _____________
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example
Write the formula
for Calcium
bicarbonate
Thursday, 16 September 2010
15. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
Sodium Fluoride _____________ Magnesium Oxide __________
Sodium Oxide _______________ Zinc Chloride _____________
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula that will cause a balance
for Calcium of positive & negative
bicarbonate charges
Thursday, 16 September 2010
16. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
Sodium Fluoride _____________ Magnesium Oxide __________
Sodium Oxide _______________ Zinc Chloride _____________
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
Thursday, 16 September 2010
17. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
Sodium Fluoride _____________ Magnesium Oxide __________
Sodium Oxide _______________ Zinc Chloride _____________
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
2. Writing it out without the charges
Thursday, 16 September 2010
18. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
Sodium Fluoride _____________ Magnesium Oxide __________
Sodium Oxide _______________ Zinc Chloride _____________
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
2. Writing it out without the charges 2 Ca HCO3
Thursday, 16 September 2010
19. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
Sodium Fluoride _____________ Magnesium Oxide __________
Sodium Oxide _______________ Zinc Chloride _____________
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
2. Writing it out without the charges 2 Ca HCO3
3. Put the subscripts in place to reflect the
ratio
Thursday, 16 September 2010
20. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
Sodium Fluoride _____________ Magnesium Oxide __________
Sodium Oxide _______________ Zinc Chloride _____________
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
2. Writing it out without the charges 2 Ca HCO3
3. Put the subscripts in place to reflect the 3 Ca(HCO3)2
ratio
Thursday, 16 September 2010
21. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
Sodium Fluoride _____________ Magnesium Oxide __________
Sodium Oxide _______________ Zinc Chloride _____________
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
2. Writing it out without the charges 2 Ca HCO3
3. Put the subscripts in place to reflect the 3 Ca(HCO3)2
ratio
Thursday, 16 September 2010
22. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
Sodium Fluoride _____________ Magnesium Oxide __________
Sodium Oxide _______________ Zinc Chloride _____________
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
2. Writing it out without the charges 2 Ca HCO3
3. Put the subscripts in place to reflect the 3 Ca(HCO3)2
ratio
Note
The “1” is never shown as a subscript
Ions that are made up of groups must be bracketed if the subscript is “2” or
more.
Thursday, 16 September 2010
23. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
NaF
Sodium Fluoride _____________ Magnesium Oxide __________
Sodium Oxide _______________ Zinc Chloride _____________
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
2. Writing it out without the charges 2 Ca HCO3
3. Put the subscripts in place to reflect the 3 Ca(HCO3)2
ratio
Note
The “1” is never shown as a subscript
Ions that are made up of groups must be bracketed if the subscript is “2” or
more.
Thursday, 16 September 2010
24. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
NaF
Sodium Fluoride _____________ Magnesium Oxide __________ MgO
Sodium Oxide _______________ Zinc Chloride _____________
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
2. Writing it out without the charges 2 Ca HCO3
3. Put the subscripts in place to reflect the 3 Ca(HCO3)2
ratio
Note
The “1” is never shown as a subscript
Ions that are made up of groups must be bracketed if the subscript is “2” or
more.
Thursday, 16 September 2010
25. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
NaF
Sodium Fluoride _____________ Magnesium Oxide __________ MgO
Sodium Oxide Na2O
_______________ Zinc Chloride _____________
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
2. Writing it out without the charges 2 Ca HCO3
3. Put the subscripts in place to reflect the 3 Ca(HCO3)2
ratio
Note
The “1” is never shown as a subscript
Ions that are made up of groups must be bracketed if the subscript is “2” or
more.
Thursday, 16 September 2010
26. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
NaF
Sodium Fluoride _____________ Magnesium Oxide __________ MgO
Sodium Oxide Na2O
_______________ ZnCl2
Zinc Chloride _____________
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
2. Writing it out without the charges 2 Ca HCO3
3. Put the subscripts in place to reflect the 3 Ca(HCO3)2
ratio
Note
The “1” is never shown as a subscript
Ions that are made up of groups must be bracketed if the subscript is “2” or
more.
Thursday, 16 September 2010
27. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
NaF
Sodium Fluoride _____________ Magnesium Oxide __________ MgO
Sodium Oxide Na2O ZnCl2
_______________ Zinc Chloride _____________
Pb(NO3)2
Lead Nitrate ______________ Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
2. Writing it out without the charges 2 Ca HCO3
3. Put the subscripts in place to reflect the 3 Ca(HCO3)2
ratio
Note
The “1” is never shown as a subscript
Ions that are made up of groups must be bracketed if the subscript is “2” or
more.
Thursday, 16 September 2010
28. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
NaF
Sodium Fluoride _____________ Magnesium Oxide __________ MgO
Sodium Oxide Na2O ZnCl2
_______________ Zinc Chloride _____________
Pb(NO3)2
Lead Nitrate ______________ K2SO4
Potassium Sulphate ____________
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
2. Writing it out without the charges 2 Ca HCO3
3. Put the subscripts in place to reflect the 3 Ca(HCO3)2
ratio
Note
The “1” is never shown as a subscript
Ions that are made up of groups must be bracketed if the subscript is “2” or
more.
Thursday, 16 September 2010
29. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
NaF
Sodium Fluoride _____________ Magnesium Oxide __________ MgO
Sodium Oxide Na2O ZnCl2
_______________ Zinc Chloride _____________
Pb(NO3)2
Lead Nitrate ______________ K2SO4
Potassium Sulphate ____________
Ca(HCO3)2
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
2. Writing it out without the charges 2 Ca HCO3
3. Put the subscripts in place to reflect the 3 Ca(HCO3)2
ratio
Note
The “1” is never shown as a subscript
Ions that are made up of groups must be bracketed if the subscript is “2” or
more.
Thursday, 16 September 2010
30. WRITING FORMULAE Copy
Examples
Use your table of ions to write formluae for the following ionic compounds:
NaF
Sodium Fluoride _____________ Magnesium Oxide __________ MgO
Sodium Oxide Na2O ZnCl2
_______________ Zinc Chloride _____________
Pb(NO3)2
Lead Nitrate ______________ K2SO4
Potassium Sulphate ____________
Ca(HCO3)2 Al2O3
Calcium Hydrogen Carbonate __________ Aluminium Oxide _______
Method 1: Working with ratios THE PROCESS FOR WRITING FORMULAE
Example 1. Work out the ratio of ions
Write the formula
for Calcium
that will cause a balance 1 Ca2+ HCO3 -
of positive & negative
bicarbonate 1 : 2
charges
2. Writing it out without the charges 2 Ca HCO3
3. Put the subscripts in place to reflect the 3 Ca(HCO3)2
ratio
Note
The “1” is never shown as a subscript
Ions that are made up of groups must be bracketed if the subscript is “2” or
more.
Thursday, 16 September 2010
31. Copy
Method 2: The swop and drop method
1. Write the ions down next to each other.
2. Drop each number down (without the charge) and
swop it to make the subscript of the other element
Example Write the formula for Aluminium Oxide
The valencies
If you are given the
formula then think
backwards to determine
the valencies.
Thursday, 16 September 2010
32. Copy
Method 2: The swop and drop method
1. Write the ions down next to each other.
2. Drop each number down (without the charge) and
swop it to make the subscript of the other element
Example Write the formula for Aluminium Oxide
The valencies
1
Al O 3+ 2-
If you are given the
formula then think
backwards to determine
the valencies.
Thursday, 16 September 2010
33. Copy
Method 2: The swop and drop method
1. Write the ions down next to each other.
2. Drop each number down (without the charge) and
swop it to make the subscript of the other element
Example Write the formula for Aluminium Oxide
The valencies
1
Al O 3+ 2-
If you are given the
formula then think
backwards to determine
the valencies.
Thursday, 16 September 2010
34. Copy
Method 2: The swop and drop method
1. Write the ions down next to each other.
2. Drop each number down (without the charge) and
swop it to make the subscript of the other element
Example Write the formula for Aluminium Oxide
The valencies
1
Al O 3+ 2-
If you are given the
formula then think
backwards to determine
the valencies.
Thursday, 16 September 2010
35. Copy
Method 2: The swop and drop method
1. Write the ions down next to each other.
2. Drop each number down (without the charge) and
swop it to make the subscript of the other element
Example Write the formula for Aluminium Oxide
The valencies
1
Al O 3+ 2-
2
Al2O3 If you are given the
formula then think
backwards to determine
the valencies.
Thursday, 16 September 2010
37. UTILIZING BONDING POTENTIAL
Valency can be shown using bonding symbols
Examples
Phosphorus has a valency of 3 and so has the potential to form 3 covalent bonds.
Sometimes written:
P
Thursday, 16 September 2010
39. Wri$ng
Chemical
Equa$ons
Chemical
reac$ons
are
the
chemists
shorthand
way
of
describing
chemical
reac$ons.
Thursday, 16 September 2010
40. Wri$ng
Chemical
Equa$ons
Chemical
reac$ons
are
the
chemists
shorthand
way
of
describing
chemical
reac$ons.
The
equa$ons
can
be
either:
Thursday, 16 September 2010
41. Wri$ng
Chemical
Equa$ons
Chemical
reac$ons
are
the
chemists
shorthand
way
of
describing
chemical
reac$ons.
The
equa$ons
can
be
either:
1.
Word
equa$ons
Thursday, 16 September 2010
42. Wri$ng
Chemical
Equa$ons
Chemical
reac$ons
are
the
chemists
shorthand
way
of
describing
chemical
reac$ons.
The
equa$ons
can
be
either:
1.
Word
equa$ons
or
2.
Balanced
symbol
equa$ons
Thursday, 16 September 2010
43. Wri$ng
Chemical
Equa$ons
Chemical
reac$ons
are
the
chemists
shorthand
way
of
describing
chemical
reac$ons.
The
equa$ons
can
be
either:
1.
Word
equa$ons
or
2.
Balanced
symbol
equa$ons
Thursday, 16 September 2010
44. Wri$ng
Chemical
Equa$ons
Chemical
reac$ons
are
the
chemists
shorthand
way
of
describing
chemical
reac$ons.
The
equa$ons
can
be
either:
1.
Word
equa$ons
or
2.
Balanced
symbol
equa$ons
For
both
types
all
reactants
(star$ng
substances)
and
products
of
the
reac$on
(end
substances)
must
be
correctly
iden$fied.
Thursday, 16 September 2010
45. Symbol
Equa$ons
Each
reactant
and
product
is
represented
by
a
formula
that
represents
the
smallest
par$cle
that
can
take
part
in
the
reac$on.
Thursday, 16 September 2010
46. Symbol
Equa$ons
Each
reactant
and
product
is
represented
by
a
formula
that
represents
the
smallest
par$cle
that
can
take
part
in
the
reac$on.
The
formula
of
any
solid
element
is
simply
the
symbol
(i.e.
for
one
atom)
Thursday, 16 September 2010
47. Symbol
Equa$ons
Each
reactant
and
product
is
represented
by
a
formula
that
represents
the
smallest
par$cle
that
can
take
part
in
the
reac$on.
The
formula
of
any
solid
element
is
simply
the
symbol
(i.e.
for
one
atom)
Thursday, 16 September 2010
48. Symbol
Equa$ons
Each
reactant
and
product
is
represented
by
a
formula
that
represents
the
smallest
par$cle
that
can
take
part
in
the
reac$on.
The
formula
of
any
solid
element
is
simply
the
symbol
(i.e.
for
one
atom)
e.g.
Magnesium
Metal
use
Mg
Thursday, 16 September 2010
50. Balancing
Equa$ons
Equa$ons
must
be
“balanced”.
This
is
based
on
the
fact
that
during
a
reac$on
no
atoms
are
destroyed,
nor
are
any
new
atoms
created.
Therefore
the
numbers
of
each
type
of
atom
in
the
reactants
must
equal
the
number
of
each
type
of
atom
in
the
products.
Thursday, 16 September 2010
52. Rules:
1. Name
all
of
the
reactants
and
products
Thursday, 16 September 2010
53. Rules:
1. Name
all
of
the
reactants
and
products
2. Write
the
correct
formula
for
each
substance
involved.
Thursday, 16 September 2010
54. Rules:
1. Name
all
of
the
reactants
and
products
2. Write
the
correct
formula
for
each
substance
involved.
3.
Balance
so
the
number
of
each
type
of
atoms
remains
the
same
during
the
reac$on.
Formula
can
not
be
changed,
so
balancing
must
be
done
by
changing
the
number
of
par$cles
involved.
Thursday, 16 September 2010
55. EQUATION 1
Potassium
+
Chlorine
(g)
Potassium
chloride
K
+
Cl2
KCl
2
K
+
Cl2
2
KCl
i.e.
2
atoms
of
potassium
react
with
1
molecule
of
chlorine
to
produce
2
units
of
potassium
chloride.
Why
“units”?
Thursday, 16 September 2010
56. EQUATION 1
Potassium
+
Chlorine
(g)
Potassium
chloride
K
+
Cl2
KCl
2
K
+
Cl2
2
KCl
i.e.
2
atoms
of
potassium
react
with
1
molecule
of
chlorine
to
produce
2
units
of
potassium
chloride.
Why
“units”?
Thursday, 16 September 2010
57. EQUATION 1
Potassium
+
Chlorine
(g)
Potassium
chloride
K
+
Cl2
KCl
Thursday, 16 September 2010
58. EQUATION 1
Potassium
+
Chlorine
(g)
Potassium
chloride
K
+
Cl2
KCl
Thursday, 16 September 2010
59. EQUATION 1
Potassium
+
Chlorine
(g)
Potassium
chloride
K
+
Cl2
KCl
2
K
+
Cl2
2
KCl
Thursday, 16 September 2010
60. EQUATION 1
Potassium
+
Chlorine
(g)
Potassium
chloride
K
+
Cl2
KCl
2
K
+
Cl2
2
KCl
Thursday, 16 September 2010
61. EQUATION 1
Potassium
+
Chlorine
(g)
Potassium
chloride
K
+
Cl2
KCl
2
K
+
Cl2
2
KCl
i.e.
2
atoms
of
potassium
react
with
1
molecule
of
chlorine
to
produce
2
units
of
potassium
chloride.
Thursday, 16 September 2010
62. EQUATION 1
Potassium
+
Chlorine
(g)
Potassium
chloride
K
+
Cl2
KCl
2
K
+
Cl2
2
KCl
i.e.
2
atoms
of
potassium
react
with
1
molecule
of
chlorine
to
produce
2
units
of
potassium
chloride.
Why
“units”?
Thursday, 16 September 2010
63. EQUATION 2
Sodium
+
Oxygen
(g)
Sodium
oxide
Na
+
O2
Na2O
4
Na
+
O2
2
Na2O
Thursday, 16 September 2010
64. EQUATION 2
Sodium
+
Oxygen
(g)
Sodium
oxide
Na
+
O2
Na2O
4
Na
+
O2
2
Na2O
Thursday, 16 September 2010
65. EQUATION 2
Sodium
+
Oxygen
(g)
Sodium
oxide
Na
+
O2
Na2O
Thursday, 16 September 2010
66. EQUATION 2
Sodium
+
Oxygen
(g)
Sodium
oxide
Na
+
O2
Na2O
Thursday, 16 September 2010
67. EQUATION 2
Sodium
+
Oxygen
(g)
Sodium
oxide
Na
+
O2
Na2O
4
Na
+
O2
2
Na2O
Thursday, 16 September 2010
103. Copy
OXIDATION and REDUCTION
Definitions
“LEO the lion Loss of Electrons is Oxidation
goes GER” Gain of Electrons is Reduction
• Oxidation is also the addition of oxygen or the removal of hydrogen.
• Reduction is the removal of oxygen or the addition of hydrogen.
• Oxidation and reduction always occur together
Oxidants & Reductants
• An oxidant is a substance that causes oxidation and is itself reduced.
Example: In the reaction between Zinc and Oxygen, Oxygen is the oxidant. It has
caused Zinc to gain oxygen. Zinc Oxide is produced.
• A reductant is a substance that causes reduction and is itself oxidised.
Example: In the reaction between Hydrogen and Copper oxide, Hydrogen is the
reductant. It has caused Copper oxide to lose oxygen. Copper is produced.
Thursday, 16 September 2010
104. Half equations Copy
REDOX
REACTION TYPES
Simple electron transfer
Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms
become ions.
Example 1
Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO
Thursday, 16 September 2010
105. Half equations Copy
REDOX
REACTION TYPES
Simple electron transfer
Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms
become ions.
Example 1
Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO
Magnesium loses electrons to form ions
Thursday, 16 September 2010
106. Half equations Copy
REDOX
REACTION TYPES
Simple electron transfer
Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms
become ions.
Example 1
Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO
Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2
Thursday, 16 September 2010
107. Half equations Copy
REDOX
REACTION TYPES
Simple electron transfer
Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms
become ions.
Example 1
Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO
Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2
Oxygen gains electrons to form ions
Thursday, 16 September 2010
108. Half equations Copy
REDOX
REACTION TYPES
Simple electron transfer
Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms
become ions.
Example 1
Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO
Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2
Oxygen gains electrons to form ions O2 + 4e- --> 2O2-
Thursday, 16 September 2010
109. Half equations Copy
REDOX
REACTION TYPES
Simple electron transfer
Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms
become ions.
Example 1
Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO
Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2
Oxygen gains electrons to form ions O2 + 4e- --> 2O2-
Thursday, 16 September 2010
110. Half equations Copy
REDOX
REACTION TYPES
Simple electron transfer
Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms
become ions.
Example 1
Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO
Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2
Oxygen gains electrons to form ions O2 + 4e- --> 2O2-
These equations can only be added once the first equation has
been doubled. This ensures that the number of electrons gained
in the reaction equals the number of electrons lost.
Thursday, 16 September 2010
111. Half equations Copy
REDOX
REACTION TYPES
Simple electron transfer
Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms
become ions.
Example 1
Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO
Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2
Oxygen gains electrons to form ions O2 + 4e- --> 2O2-
These equations can only be added once the first equation has
been doubled. This ensures that the number of electrons gained
in the reaction equals the number of electrons lost.
Adding the two equations and cancelling the charges gives the final equation.
The final equation describes both the reduction and oxidation together:
Thursday, 16 September 2010
112. Half equations Copy
REDOX
REACTION TYPES
Simple electron transfer
Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms
become ions.
Example 1
Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO
Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2
Oxygen gains electrons to form ions O2 + 4e- --> 2O2-
These equations can only be added once the first equation has
been doubled. This ensures that the number of electrons gained
in the reaction equals the number of electrons lost.
Adding the two equations and cancelling the charges gives the final equation.
The final equation describes both the reduction and oxidation together:
2Mg + O2 + 4e- --> 2 Mg2+ + 2O2- + 4e-
Thursday, 16 September 2010
113. Half equations Copy
REDOX
REACTION TYPES
Simple electron transfer
Reactions that involve atoms losing or gaining electrons. Ions become atoms, atoms
become ions.
Example 1
Burning magnesium in oxygen - final equation: 2Mg + O2 --> 2MgO
Magnesium loses electrons to form ions (Mg --> Mg2+ + 2e-) x 2
Oxygen gains electrons to form ions O2 + 4e- --> 2O2-
These equations can only be added once the first equation has
been doubled. This ensures that the number of electrons gained
in the reaction equals the number of electrons lost.
Adding the two equations and cancelling the charges gives the final equation.
The final equation describes both the reduction and oxidation together:
2Mg + O2 + 4e- --> 2 Mg2+ + 2O2- + 4e-
2Mg + O2 --> 2MgO
Thursday, 16 September 2010
114. Spectator ions Copy
Example 2
Zinc powder added to Copper Sulphate solution. Sulphate ion is a spectator ion.
- final equation:
Zn + CuSO4 --> Cu + ZnSO4
Zn --> Zn2+ + 2e- Oxidation
- half equations:
Cu2+ + 2e- --> Cu Reduction
Zn + Cu2+ + 2e- --> Zn2+ + Cu + 2e-
- Adding the two half equations and cancelling out the charges gives the
final equation (above).
In Summary
Half equations are used to show how electrons are lost and gained
in redox reactions (reactions involving reduction and oxidation)
Thursday, 16 September 2010
115. Copy
Example 3 (class prac)
A bright steel nail is placed in 2 mL of copper sulphate solution (0.1 molL-1) in a test tube.
Observation:
- half equations:
- final equation:
Example 4 (class prac)
A 2 cm strip of Magnesium ribbon is placed in 2 mL of Lead nitrate solution in a test tube.
Observation:
- half equations:
- final equation:
Thursday, 16 September 2010
116. Copy
Example 5 (class prac)
A 2 cm strip of Magnesium ribbon is placed in 2 mL of Silver nitrate solution in a test tube.
Observation:
- half equations:
- final equation:
Example 6 (class prac)
A small (1 - 2 cm strip) of Copper foil is placed in 2 mL of Lead nitrate solution in a test
tube.
Observation:
- half equations:
- final equation:
More redox reaction pracs (ABA P34: “Reactions 4 & 5)
Thursday, 16 September 2010
117. WHEN DISCUSSING CHEMISTRY OF
REDOX REACTION ALWAYS INCLUDE A
DISCUSSION OF ELECTRON TRANSFER IN
ADDITION TO APPLICATION OF OTHER
PRINCIPLES OF REDUCTION/OXIDATION
Thursday, 16 September 2010
119. Calcium Chloride solution (clear & colourless)
added to
Silver Nitrate solution (clear & colourless)
white precipitate.
Thursday, 16 September 2010
120. Silver Nitrate solution (clear & colourless)
added to
Sodium Sulphide solution (clear & colourless)
black precipitate
Thursday, 16 September 2010
121. Copy
WHAT IS A PRECIPITATE?
A precipitate may form when one ionic solution is added
to another. It is not possible to see through a solution
when a precipitate forms in it. The solution becomes
cloudy. The precipitate will eventually settle to the bottom
of the container.
Definition
A precipitation reaction has occurred when a solid forms as a result of a
reaction between two solutions. The solid forms because it is an insoluble
product of the reaction.
Thursday, 16 September 2010
122. HOW PRECIPITATES FORM
Example
A solution of Copper Sulphate is added to a solution of Sodium Carbonate.
Copper ions spread through the water
The copper sulphate solution contains:
Sulphate ions spread through the water
Sodium ions spread through the water
The sodium carbonate solution contains:
Carbonate ions spread through the water
Forces of attraction between the Copper ions and Sulphate ions are weak enough for the
water molecules to get between the ions. The same is true for the sodium and carbonate
ions.
The same cannot be said for the Copper ions that collide with the Carbonate ions in this
mixture. A bond forms that is stronger than the attraction that water has for the ions and
so a precipitate is formed.
The Sodium and sulphate ions are dispersed and free to move amongst the water
molecules. They are spectator ions.
Copper Sulphate + Sodium Carbonate --> Copper Carbonate + Sodium Sulphate
Ion equation:
Complete formula equation:
Thursday, 16 September 2010
123. SOLUBILITY RULES
“You can predict whether or not a compound is soluble by
using the following simple rules:”
1. All nitrates are soluble.
2. All group 1 metal compounds and ammonium compounds
are soluble.
3. All chlorides are soluble except for silver chloride and lead
chloride
4. All sulfates are soluble except for barium sulfate and lead
sulfate.
5. All carbonates are insoluble except group 1 and ammonium
compounds
6. All hydroxides and oxides are insoluble (exception Sodium
& Potassium)
Thursday, 16 September 2010
128. EQUATIONS OF DECOMPOSITION REACTIONS
A decomposition reaction is one in which a compound breaks down to form simpler
compounds. A thermal decomposition requires heat.
Word equations for simple decomposition reactions
1. The thermal decomposition of carbonates, Eg ...
Calcium Carbonate --> Calcium Oxide + Carbon Dioxide
Copper Carbonate --> Copper Oxide + Carbon Dioxide
2. The thermal decomposition of sodium bicarbonate, Eg...
Sodium Bicarbonate --> Sodium Carbonate + Water + Carbon Dioxide
3. The decomposition of hydroxides
Copper Hydroxide --> Copper Oxide + Water
Note
Not all metal carbonates, hydrogen carbonates and hydroxides will decompose on
heating. Position on the reactivity series is an important factor
Thursday, 16 September 2010
129. REACTIVITY SERIES OF METALS
Most reactive K
Na
Li In a simple electron exchange reaction
(redox), a metal higher in the series will
Ca
donate electrons to one that is lower in
Mg the series
Al
Zn
Example
Fe
Sn Zn(s) + CuSO4(aq) ---> ZnSO4(aq) + Cu(s)
Pb
Grey Blue Colourless orange-brown
Cu
Hg
Ag
Least reactive
Au
Thursday, 16 September 2010
131. ATOMIC & MOLECULAR MASSES
The mole
Consider the formation of Carbon Monoxide:
C + O ---> CO
This is often understood as meaning
“1 atom of C” + “1 atom of O” ---> “1 molecule of CO”
But working with single atoms when you are performing calculations involving mass
means working with masses that are too small.
The chemist needs to find a larger unit so that masses in calculations are realistic.
This unit is called the mole.
A mole is a unit that consists of 6.023 x 1023 objects.
Atomic masses
“This means that 1 mole of hydrogen
atomic 1 (6.023 x 1023 atoms) has a mass of 1.0 g.”
number
H
Relative atomic
1.0
mass, Ar “The atomic mass of Carbon is
12 gmol-1.”
Thursday, 16 September 2010
132. Mr = Relative molecular mass
= the number of grams per mole for the compound.
A formula gives us the mole ratio of each type of atom in a compound.
Molecular masses can be calculated from relative atomic mass values and
formulae.
Example
The formula for Methane is CH4.
This means that in a sample of Methane there are 4 moles of hydrogen atoms
for every mole of carbon.
Mr(CH4) = the number of grams per mole of methane molecules.
The periodic table tells us that:
C = 12.0g per mole
H = 1.0g per mole
So ......
Mr(CH4) = 12.0 + 4 x 1.0 = 16 gmol-1
Thursday, 16 September 2010
133. Example: A question from the 2003 NCEA examination paper
Thursday, 16 September 2010
134. Example: A question from the 2003 NCEA examination paper
Mr(FeCO3) = 55.9 + 12 + (3 x 16) = 115.9 gmol-1
Thursday, 16 September 2010
135. Example: A question from the 2003 NCEA examination paper
Mr(FeCO3) = 55.9 + 12 + (3 x 16) = 115.9 gmol-1
Mr[Fe(NO3)3] = 55.9 + (3 x 14) + (9 x 16) = 241.9 gmol-1
Thursday, 16 September 2010
136. Example: A question from the 2003 NCEA examination paper
Mr(FeCO3) = 55.9 + 12 + (3 x 16) = 115.9 gmol-1
Mr[Fe(NO3)3] = 55.9 + (3 x 14) + (9 x 16) = 241.9 gmol-1
Mr(Fe2O3) = 2 x 55.9 + 3 x 16 = 159.8 gmol-1
Thursday, 16 September 2010
137. A question from the 2005 NCEA examination paper
“Try these questions out for yourself”
ESA: Ex 12A
Thursday, 16 September 2010
138. A question from the 2005 NCEA examination paper
“Try these questions out for yourself”
159.6 gmol-1
ESA: Ex 12A
Thursday, 16 September 2010
139. A question from the 2005 NCEA examination paper
“Try these questions out for yourself”
159.6 gmol-1
106 gmol-1
ESA: Ex 12A
Thursday, 16 September 2010
140. A question from the 2005 NCEA examination paper
“Try these questions out for yourself”
159.6 gmol-1
106 gmol-1
261 gmol-1
ESA: Ex 12A
Thursday, 16 September 2010
141. PERCENTAGE COMPOSITION
Percentage composition of an element/s in a compound is the ratio of the mass per
mole of the element/s to the mass per mole of the compound expressed as a
percentage.
Example
Consider that you need to calculate the percentage of Sulfur in Copper Sulphate. The
relative atomic masses are:
Cu = 63.5 gmol-1
S = 32.1 gmol-1
O = 16.0 gmol-1
Mr (CuSO4) = 159.6 gmol-1 (from previous question)
Ar (S) = 32.1 gmol-1
Percentage Sulfur = 32.1 = 20.1%
159.6
Thursday, 16 September 2010