Download Structures and Bonding

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C2 Chemical Resources
OCR Gateway Additional Science
W Richards
The Weald School
Fundamental Concepts
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Chemical formulae
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The chemical formulae of a molecule or compound is simply a
way of showing the ratio of atoms in it. For example…
Na
Cl
= sodium chloride (NaCl)
K
I
= potassium iodide (KI)
O
K
N
O
O
= potassium nitrate (KNO3)
Chemical formulae
Try drawing these:
1) Water H2O
2) Carbon dioxide CO2
3) Calcium sulphate CaSO4
4) Magnesium hydroxide Mg(OH)2
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Naming compounds
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Rule 1– If two identical elements combine then the
name doesn’t change
This happens with the following elements:
1) H2
4) F2
2) N2
5) Cl2
3) O2
6) Br2
Naming compounds
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Rule 2 – When two elements join and one is a halogen,
oxygen or sulphur the name ends with ____ide
e.g. Magnesium + oxygen
magnesium oxide
1) Sodium + chlorine
6) KBr
2) Magnesium + fluorine
7) LiCl
3) Lithium + iodine
8) CaO
4) Chlorine + copper
9) MgS
5) Oxygen + iron
10)KF
Naming compounds
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Rule 3 – When three or more elements combine and two of
them are hydrogen and oxygen the name ends with
hydroxide
e.g. Sodium + hydrogen + oxygen
Sodium hydroxide
1) Potassium + hydrogen + oxygen
2) Lithium + hydrogen + oxygen
3) Calcium + hydrogen + oxygen
4) Mg(OH)2
Naming compounds
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Rule 4 – When three or more elements combine and
one of them is oxygen the ending is _____ate
e.g. Copper + sulphur + oxygen
Copper sulphate
1) Calcium + carbon + oxygen
6) AgNO3
2) Potassium + carbon + oxygen
7) H2SO4
3) Calcium + sulphur + oxygen
8) K2CO3
4) Magnesium + chlorine + oxygen
5) Calcium + oxygen + nitrogen
Simple formulae to learn
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H2O
Water
NaCl
Sodium chloride
CO2
Carbon dioxide
CaCl2
Calcium chloride
NH3
Ammonia
MgO
Magnesium oxide
H2
Hydrogen
HCl
Hydrochloric acid
O2
Oxygen
NaOH
Sodium hydroxide
N2
Nitrogen
Ca(OH)2
Calcium hydroxide
K2SO4
Potassium sulfate
CaCO3
Calcium carbonate
Cl2
Chlorine
HNO3
Nitric acid
KCl
Potassium chloride
H2SO4
Sulphuric acid
CuO
Copper oxide
Mg(OH)2
Magnesium hydroxide
Na2CO3
Sodium carbonate
MgCl2
Magnesium chloride
(NH4)2SO4 Ammonium sulfate
Simple chemical reactions
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H
Mg
O
Cl
H
Cl
Cl
Magnesium + Hydrochloric
oxide
acid
MgO
+
2HCl
Mg
H
Cl
Magnesium
chloride
+
Water
MgCl2
+
H2O
O
O
Mg
Cu
O
S
O
Cu
Mg
Mg
+
Copper
sulphate
CuSO4
O
S
O
O
O
Magnesium +
O H
Copper
+
Magnesium
sulphate
Cu
+
MgSO4
Notice that the number of atoms on each side of the equation is the same!
Balancing equations
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Consider the following reaction:
Sodium + water
Na
+
sodium hydroxide + hydrogen
Na
O
H
H
O
H
+
H
H
This equation doesn’t balance – there are 2 hydrogen
atoms on the left hand side (the “reactants” and 3 on
the right hand side (the “products”)
Balancing equations
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We need to balance the equation:
Sodium + water
sodium hydroxide + hydrogen
Na
O
H
Na
+
Na
H
O
O
H
Na
H
O
H
+
H
H
Now the equation is balanced, and we can write it as:
2Na(s) + 2H2O(l)
2NaOH(aq) + H2(g)
H
Some examples
2Mg
O2
2 MgO
Zn
+ 2 HCl
ZnCl2
2 Fe
+ 3Cl2
2 FeCl3
NaOH
CH4
Ca
+
+
HCl
+ 2 O2
NaCl
CO2
+
+
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H2
H 2O
+ 2H2O
+ 2 H2O
Ca(OH)2
+
+
H2SO4
Na2SO4
+ 2H2O
2 CH3OH
+ 3 O2
2 NaOH
2 CO2
+ 4H2O
H2
Bonding Introduction
Cl
Hi. My name’s Johnny Chlorine.
I’m in Group 7, so I have 7
electrons in my outer shell
I’d quite like to have a full outer
shell. To do this I need to GAIN
an electron. Who can help me?
Cl
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Ionic Bonding
Here comes my friend again, Sophie
Sodium
Cl
Na
Hey Johnny. I’m in Group 1 so I have
one electron in my outer shell. Unlike
Harry, this electron is far away from
the nucleus so I’m quite happy to get
rid of it. Do you want it?
Okay
+
Cl
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Na
Now we’ve both got full outer shells
and we’ve both gained a charge.
We’ve formed an IONIC bond, which
is basically caused by the attraction
between our charges.
Covalent Bonding
Cl
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Here comes another one of my
friends, Harry Hydrogen
Hey Johnny. I’ve only got one
electron but it’s really close to my
nucleus so I don’t want to lose it.
Fancy sharing?
Cl
H
Now we’re both really stable.
We’ve formed a covalent bond.
H
Balancing ions
Some common ions:
Sodium – Na+
Chloride – Cl-
Potassium – K+
Bromide – Br-
Magnesium – Mg2+
Oxide – O2-
Ammonium – NH4+
Sulphate – SO42-
Determine the formula of the following compounds:
1) Sodium chloride
2) Magnesium oxide
3) Magnesium chloride
4) Ammonium chloride
5) Sodium sulphate
6) Sodium oxide
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Atom, molecule or ion?
Are the following things atoms, molecules or ions?
1) H2
1) Molecule
2) NH3
2) Molecule
3) Cl-
3) Ion
4) K2SO4
4) Molecule
5) Au
5) Atom
6) CO32-
6) Ion
7) Na
7) Atom
8) CO2
8) Molecule
9) H+
9) Ion
10)H2O
10)Molecule
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C2a The Structure of the Earth
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The Structure of the Earth
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A thin, relatively cold
crust - 10-100km thick
and not very dense
A mantle – has the
properties of a solid
but the lower parts
can also flow
A core – made of
molten nickel and iron.
Outer part is liquid
and inner part is solid
Scientists have learnt this by studying seismic waves
(earthquakes) as the crust is too think to drill through.
Movement of the Lithosphere
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The Earth’s LITHOSPHERE (i.e. the _______) is split
up into different sections called ________ plates:
These plates are moving apart from each other a
few centimetres every _______ due to the
________ currents in the mantle caused by the
________ decay of rocks inside the core.
Words – radioactive, crust, convection, tectonic, year
Plate Movements
Earthquakes and
volcanic eruptions can
be common here
Igneous Rock
Oceanic Crust
Mantle
Convection
Currents
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Magma
More on Plate Movements
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Subduction
Thin, dense oceanic plate
Convection
Currents
Thick, less dense
continental plate
Tectonic Plate movements
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Look at the coastlines of South
America and Africa. I wonder of they
used to fit together…
Alfred
Wegener
I’m going to call this my
Theory of Continental Drift
Tectonic theory
What’s my evidence for this? Three things:
1) The “jigsaw fit”
2) Each continent has similar rocks and fossils
3) Each continent has similar animal species
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The Evidence:
Tectonic theory
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1) Some continents look like they used to “fit”
together
2) Similar rock patterns and fossil records
The Problems:
Wegener couldn't explain how continental drift
happened so nobody believed him
The Answer:
1) Scientists discovered 50 years later that the Earth generates massive
amounts of heat through radioactive decay in the core. This heat
generated convection currents in the mantle causing the crust to move
2) We also now know that the sea floor is spreading outwards from plate
boundaries
Conclusion – scientists now believe Wegener’s Tectonic
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Another Example of Continental Drift
The formation of mountain ranges can be explained by tectonic
theory. Consider the Himalayas at the top of India:
This is where
India is now
This is where
India was millions
of years ago
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Magnetic Patterns in Sea Floor Spreading
The Earth’s magnetic field swaps poles every million years.
The above picture shows those changes recorded over time in
rocks on the sea floor and provides evidence for long-term sea
floor spreading.
Igneous Rock
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Granite – a slow cooling
rock with big crystals
and rich in silica
Rhyolite – a fast cooling
rock with small crystals
and rich in silica
Basalt – a fast cooling rock with
small crystals and rich in iron
Gabbro – a slow cooling rock with
big crystals and rich in iron
Volcanoes
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What do you
think of the
following photo?
Picture: EPA
Geologists study volcanoes to get better at forecasting future
ones and to reveal more information about the structure of
the Earth.
C2b Construction Materials
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Building Materials
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Many of our common building materials are found in the Earth:
Iron and aluminium
come from ores.
Glass is made
from sand
Bricks are made from clay
Building Materials
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Here are some common rocks used in buildings:
Limestone – a
sedimentary
rock so fairly
soft
Marble (made from
chalk or limestone
under high pressure
and heat) and fairly
hard
Granite – an
igneous rock and
very hard
Limestone
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Limestone is a __________ rock made up of
mainly calcium _______. It’s cheap and easy to
obtain. Some facts:
1) Building materials – limestone can be quarried
and cut into blocks to be used in buildings.
However, it is badly affected by ____ ____.
2) Limestone ________ when heated to form
calcium oxide and carbon dioxide:
Calcium carbonate
CaCO3
HEAT
HEAT
calcium oxide + carbon dioxide
CaO + CO2
3) Cement making – limestone can be “roasted” in a rotary kiln
to produce dry cement. It’s then mixed with sand and
aggregate to make _______.
Words – concrete, acid rain, carbonate, sedimentary, decomposes
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Pros and Cons of quarrying limestone
Reasons why quarrying limestone
is a good idea
Reasons why quarrying limestone
is a bad idea
Concrete
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Concrete is a strong building material and can be made even
stronger with reinforcements:
Reinforcing concrete is
better than plain concrete
because it is both stronger
and the steel is more
flexible.
C2c Metals and Alloys
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Extracting Metals
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Some definitions:
A METAL ORE is a mineral or mixture of
minerals from which it is “economically
viable” to extract some metal.
Most ores contain METAL OXIDES (e.g. rust = iron oxide).
To “extract” a metal from a metal oxide we need to REDUCE
the oxygen. This is called a REDUCTION reaction. To put it
simply:
Iron
ore
Iron
Oxide
“Reduce” the oxygen
to make iron
How do we do it?
Potassium
Sodium
Calcium
Magnesium
Aluminium
Carbon
Zinc
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Metals ABOVE CARBON, because
of their high reactivity, are
extracted by ELECTROLYSIS
Metals BELOW CARBON are
extracted by heating them with
carbon in a BLAST FURNACE.
This is a “displacement reaction”
Iron
Tin
Carbon
Copper Oxide
Lead
Copper
Silver
Gold
Platinum
These LOW REACTIVITY metals won’t
need to be extracted because they are
SO unreactive you’ll find them on their
own, not in a metal oxide
Reducation and Oxidation
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OIL RIG
Oxidation is Loss of Electrons
Reduction is Gain of Electrons
An example of reduction:
Aluminium + iron oxide
2Al(s) + Fe2O3(s)
heat
aluminium oxide + iron
heat
Al2O3(s) + 2Fe(s)
An example of oxidation:
Magnesium + oxygen
Mg(s) + O2(s)
heat
heat
magnesium oxide
2MgO(s)
Purifying Copper
Impure
copper
Solution
containing
copper ions
+
+ Cu
+ Cu
+ Cu
At the anode:
Cu(s)
Cu2+(aq) + 2e-
“Oxidation”
2+
2+
2+
-
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Pure copper
At the cathode:
Cu2+(aq) + 2e-
“Reduction”
Cu(s)
Recycling metals
Reasons why recycling is good
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Reasons why recycling is bad
Still requires
energy
Reduces demand
for raw materials
Recycling
Requires money to
sort and recycle
Saves energy
Alloys
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Steel is an “alloy” – i.e. a mixture of metals. Here are other
alloys:
Gold mixed with
copper
Aluminium mixed
with magnesium
and copper
Aluminiun mixed
with chromium
Alloys and their uses
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Here are some common alloys and their main uses and metals:
Brass –
copper and
zinc
Amalgam mercury
Solder – lead
and tin
Smart Alloys
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A “smart alloy” is one that can “remember” its original state
after being bent or stretched.
These glasses are made from a “smart” material – if they are
bent they will return to their original shape
Gold alloys
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Gold can be mixed with other metals to make alloys with
different properties. For example:
24-Carat gold
9-Carat gold
“Pure gold” – 99.99% of the atoms
in this bar are gold atoms (fineness
off 999.9). Pure and malleable but
soft.
“9 carat gold” – around 9/24ths
of the atoms in these earrings
are gold atoms. Harder than
pure gold but less malleable.
C2d Making Cars
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Materials in a Car
Copper wires
Glass
windscreen
Plastic trim
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Nylon
seatbelts
Steel body
Alloy wheels
Rusting
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Task: To investigate what causes rusting
Tube 1 –
drying
agent
Tube 2 –
boiled
water
Tube 3 –
water + air
Tube 4 –
water + air
+ salt
Rusting
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“Rusting” is the adding of oxygen to iron to form iron oxide (this is called
“oxidation”)
No rust
No rust
Iron + oxygen + water
Rust
Lots of rust
hydrated iron oxide
Salt water and acid rain can also increase the rate of rusting.
Aluminium:
Iron or aluminium?
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Does not corrode as it does not oxidise
Less dense and lighter and cars are therefore more efficient
More expensive but the car is more efficient and lasts longer
Iron:
Cheaper than aluminium
Magnetic so easily recycled
Corrodes easily but also malleable
Most cars are made from steel (an alloy of carbon)
which is harder and stronger than iron and less likely
to corrode.
Recycling
23/05/2017
From 2015 law states that 95% of a car must be made
from recycled material. Why recycle?
1) Less space will be needed for landfill sites
2) Recycled metals only need about 1/10th of the energy to
produce compared to producing new metals
3) Recycling paper reduces the amount of water and energy
needed to produce it
4) Recycled glass only needs 80% of the energy to produce
compared to producing new glass
5) Recycling saves on raw materials
6) Less excavation and mining costs
C2e Manufacturing Chemicals
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Reversible Reactions
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Some chemical reactions are reversible. In other words, they
can go in either direction:
A + B
e.g. Ammonium chloride
NH4Cl
C + D
Ammonia + hydrogen chloride
NH3 + HCl
If a reaction is EXOTHERMIC in one direction
what must it be in the opposite direction?
For example, consider copper sulphate:
Hydrated copper
sulphate (blue)
+ Heat
CuSO4.5H2O
Anhydrous copper
sulphate (white)
CuSO4 + H2O
+
Water
Reversible Reactions
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When a reversible reaction occurs in a CLOSED SYSTEM (i.e. no reactants
are added or taken away) an EQUILIBRIUM is achieved – in other words,
the reaction goes at the same rate in both directions:
A + B
Endothermic reactions
Increased temperature:
A + B
C + D
C + D
Exothermic reactions
Increased temperature:
A + B
C + D
More products
Less products
Decreased temperature:
Decreased temperature:
A + B
C + D
Less products
A + B
C + D
More products
Making Ammonia
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Guten Tag. My name is Fritz Haber and I won the Nobel
Prize for chemistry. I came up with the Haber Process
that uses nitrogen (from the air) and hydrogen (from
natural gas or cracking hydrocarbons) to make ammonia:
Nitrogen + hydrogen
Ammonia
N2 + 3H2
2NH3
Fritz Haber,
1868-1934
To produce ammonia from nitrogen and hydrogen you
have to use three conditions:
Nitrogen
Hydrogen
•High pressure
•450O C
•Iron catalyst
Mixture of NH3, H2 and
N2. This is cooled
causing NH3 to liquefy.
Recycled H2 and N2
Haber Process: The economics
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A while ago we looked at reversible reactions:
Endothermic, increased temperature
A + B
Endothermic
C + D
Exothermic, increase temperature
A + B
Nitrogen + hydrogen
Ammonia
N2 + 3H2
2NH3
C + D
Exothermic
1) If temperature was DECREASED the amount of ammonia formed would
__________...
2) However, if temperature was INCREASED the rate of reaction in both
directions would ________ causing the ammonia to form faster
3) If pressure was INCREASED the amount of ammonia formed would
INCREASE because there are less molecules on the right hand side of
the equation
Haber Process Summary
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A low temperature increases the yield of ammonia but is too
slow
A high temperature improves the rate of reaction but
decreases the yield too much
A high pressure increases the yield of ammonia but costs a lot
of money
To compromise all of these factors, these conditions are used:
Nitrogen
Hydrogen
•200 atm pressure
•450O C
•Iron catalyst
Mixture of NH3, H2
and N2. This is
cooled causing NH3
to liquefy.
Recycled H2 and N2
Industrial Processes summary
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Ammonia is an important chemical as its used to make
fertilisers and nitric acid. What does the cost of making any
chemical depend on?
What
pressures and
temperatures
are needed
Equipment
needed
Cost of
energy
Whether or
not a catalyst
can be used
Factors affecting
How much a chemical
costs to make
How quickly
the chemical
can be made
Cost of
materials
Cost of
wages
How much chemical
is made per day
Chemical Economics
23/05/2017
Hi. We’re industrial scientists and
we want to make lots of chemicals
and sell them to make money. What
problems would we face?
Therefore we need
reactions and
processes that give
us a pure, high
percentage yield
where all of the
products are useful
and the reactions
happen quickly.
Possible problems with making
chemicals:
1) Reactions often produce
chemicals that aren’t
commercially useful or that can’t
be sold
2) Reactions also need to be fast to
be economical but not so fast
that they’re dangerous!
C2f Acids and Alkalis
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Universal Indicator and the pH scale
Universal Indicator is a mixture of liquids that will produce a
range of colours to show how strong the acid or alkali is:
1
2
3
Stomach acid
4
5
Lemon juice
6
7
8
9
10
11
12 13 14
Water Soap Baking powder Oven cleaner
Strong alkali
Strong acid
Neutral
We can also use litmus paper which is red in acid or blue in
alkali.
Acids and Alkalis
1
2
3
4
5
6
7
8
9
10
11
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12 13 14
Acids produce hydrogen ions when they dissolve in water:
H
+
Cl
H
Cl
-
Alkalis produce hydroxide ions:
Na
O
H
-
+
Na
O
H
Neutralisation reactions
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An alkali is a soluble base. When acids and alkalis react
together they will NEUTRALISE each other:
Sodium hydroxide
Na
Hydrochloric acid
H
OH
The sodium “replaces”
the hydrogen from HCl
Na
Cl
Sodium chloride
General equation:
H2O
Water
H+(aq) + OH-(aq)
H2O(l)
Cl
Common acids and alkalis
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Acids
Alkalis
Hydrochloric acid, HCl
Sodium hydroxide, NaOH
Nitric acid, HNO3
Potassium hydroxide, KOH
Sulphuric acid, H2SO4
Magnesium hydroxide, Mg(OH)2
Calcium hydroxide, Ca(OH)2
Making salts
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Whenever an acid and alkali neutralise each other we are left
with a salt, like a chloride or a sulphate. Complete the
following table:
Hydrochloric
acid
Sodium
hydroxide
Potassium
hydroxide
Calcium
hydroxide
Sulphuric
acid
Nitric acid
Sodium
chloride +
water
Potassium
sulphate +
water
Calcium
nitrate +
water
Phosphoric
acid
Adding acid to carbonates
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Carbonates are compounds containing carbon and oxygen. When an acid is
added to a carbonate the carbonate starts to _______. A gas called
______ _______ is produced and the acid is neutralised.
Carbonates used to be used as building materials but aren’t any more
because acid rain would eventually ________ the building.
Words – dissolve, fizz, carbon dioxide, oxygen
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Reactions of metals carbonates with acid
A metal carbonate is a compound containing a metal, carbon
and oxygen.
METAL CARBONATE + ACID
Mg
O
O
H
C
O
H
SALT + CARBON DIOXIDE + WATER
Cl
O
Cl
Cl
Mg
Cl
C
O
Copy and complete the following reactions:
1) Magnesium carbonate + hydrochloric acid
2) Calcium carbonate + hydrochloric acid
3) Sodium carbonate + sulphuric acid
H
O
H
Reactions of metal oxides with acid
23/05/2017
A metal oxide is a compound containing a metal and oxide. They are
sometimes called BASES. For example:
Mg
O
Na
Magnesium oxide
O
Al
Na
Al
Sodium oxide
Mg
O
H
O
O
Aluminium oxide
METAL OXIDE + ACID
H
O
SALT + WATER
Cl
Cl
Cl
Mg
Cl
Copy and complete the following reactions:
1) Magnesium oxide + hydrochloric acid
2) Calcium oxide + hydrochloric acid
3) Sodium oxide + sulphuric acid
H
O H
Acids and metal hydroxides
23/05/2017
A neutralisation reaction occurs when an acid reacts with an alkali. An
alkali is a metal oxide or metal hydroxide dissolved in water.
ACID + ALKALI
Na
O
H
H
Cl
SALT + WATER
Cl
Na
Copy and complete the following reactions:
1) Sodium hydroxide + hydrochloric acid
2) Calcium hydroxide + hydrochloric acid
3) Sodium hydroxide + sulphuric acid
4) Magnesium hydroxide + sulphuric acid
H
O H
Neutralisation reactions
23/05/2017
The basic equation for any neutralisation reaction is:
H+(aq) + OH-(aq)
H2O(l)
Write word and chemical equations for the following reactions:
1) Hydrochloric acid + sodium hydroxide
2) Hydrochloric acid + potassium hydroxide
3) Nitric acid + potassium hydroxide
4) Sulphuric acid + calcium hydroxide
5) Nitric acid + copper oxide, CuO
6) Sulphuric acid + calcium carbonate, Ca(CO)3
C2g Fertilisers and Crop yields
23/05/2017
Fertilisers
Population
The human population is growing
exponentially:
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Time
Because of this trend it is important to increase food yields and fertilisers
help us to do this.
Most fertilisers are “NPK” which means
they contain _________, phosphates
and potassium to enhance plant
______. These minerals have to be
dissolved in _____ so that they can be
absorbed through _____ and carried
through the ______ stream. These
minerals replace essential elements
used by previous crops and provide
more nitrogen for plant protein.
Words – transpiration, nitrogen,
water, growth, roots
Eutrophication
23/05/2017
One possible problem with fertilisers is eutrophication. Eutrophication is
when lakes become stagnant due to careless use of fertiliser…
1) Inorganic fertilisers
used on fields are
washed into the lake
3) This growth causes
overcrowding and many plants die
due to lack of enough light or food
2) The fertiliser causes increased growth in water plants
Eutrophication
4) Microorganisms and
bacteria increase in number due
to the extra dead material
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6) The lack of oxygen
causes the death of fish
and other aquatic animals
Can’t…breathe…
5) These microorganisms
use up the oxygen in the
lake during respiration
Eutrophication
4) Microorganisms and
bacteria increase in number due
to the extra dead material
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6) The lack of oxygen
causes the death of fish
and other aquatic animals
5) These microorganisms
use up the oxygen in the
lake during respiration
Ammonium-based Fertilisers
23/05/2017
Guten tag. When ammonia dissolves in water
it produces an alkaline solution:
NH3 + H20
Fritz Haber,
1868-1934
NH4OH
This solution can be used to make fertilisers
like ammonium nitrate, ammonium phosphate
and ammonium sulfate. Very useful! I won
the Nobel Prize for Chemistry for my work in
making ammonia as my discovery has led to
increased crop yields.
Making a fertiliser
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1) Fill a burette with acid solution of known
concentration
2) Accurately measure out 25cm3 of alkali
and place it in the conical flask
3) Add indicator to the flask to tell when it
is neutralised
4) Slowly add the acid until the mixture in
the flask turns neutral
5) Evaporate some of the water and filter
off the remains to leave fertiliser crystals.
C2h Chemicals from the sea
23/05/2017
Salt
Salt (sodium chloride, NaCl) is an
important chemical and is used as
a preservative and as a flavouring.
Salt can be obtained from
seawater, salt deposits or from
mining:
What problems could salt mining
bring?
23/05/2017
Testing for Chlorine
Chlorine “bleaches” damp indicator paper
23/05/2017
Electrolysis of Salt Water
23/05/2017
Salt water (e.g. seawater or brine) can be electrolysed
using an electric current to produce chlorine and other
useful products:
Chlorine gas (Cl2) – useful
for making bleach and
plastics
Hydrogen gas (H2) –
useful as a potential fuel
source or manufacture
of HCl
Sodium
chloride
solution (salt
water)
NaCl(aq)
Positive
electrode
Negative
electrode
Sodium hydroxide
(NaOH(aq)) – useful
for making soaps and
manufacture of paper
Half equations for this process
23/05/2017
NaCl(aq) contains Na+, OH-, Cl- and H+ ions
Chlorine gas (Cl2)
Hydrogen gas (H2)
Sodium
chloride
solution (salt
water)
Sodium hydroxide
(made out of ions
that haven’t
discharged)
NaCl(aq)
At the anode:
2Cl- - 2e-
Cl2
Oxidation
Positive
electrode
(anode)
Negative
electrode
(cathode)
At the cathode:
2H+ + 2e-
H2
Reduction
Using Sodium Chloride in Industry
23/05/2017
A source of
sodium
hydroxide
Products
from it can
be used to
make bleach
and PVC
A source of
chlorine
Industrial uses
for salt
Hydrogen is used to
make margarine
Chlorine can
sterilise
water