Full C3 AQA revsion notes

Sorry it's a bit late but hopefully these will be useful for those taking the exam next year. Again a fully detailed set of notes on everything you need to know (as far as I am aware) for the AQA Triple Chemistry exam.

Everything is explained to the best of my ability in a way that I understand it - Hope this is useful :)

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  • Created on: 24-05-11 15:32
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Chemistry 3
Part 1: The Periodic Table:
John Newlands:
- Tried listing the elements in order of atomic mass.
- Every eight element was similar, but the pattern broke after the first 15.
Dmitri Meneleev:
- He left gaps in his table so similar elements always lined up.
- He even predicted properties of missing elements, his theory was accepted
when his predictions were proved accurate.
We now know that the periodic table is related to the structure of the atoms
of each element. They should be arranged according to their atomic
numbers, not masses.
The Law of Octaves: If the chemical elements are arranged according to
atomic weight those with similar physical and chemical properties occur
every 8 groups.
The law of triads: Nature contains triads of elements where the middle
element has an average of the other 2 elements when ordered by atomic
weight. E.g. lithium, sodium, potassium.
The atoms of elements in the same group have the same number of
electrons in their outer shell.
Group 1: Alkali Metals:
Low densities and are soft.
Very reactive metals.
They get more reactive as we go down the group.
Melting and boiling points decrease down the group.
Most are white compounds and soluble in water.
They react with non-metals to produce ionic compounds with a 1+ charge.
They fizz violently on water, producing hydrogen gas and an alkaline solution.
It gets easier to lose outer electrons the further away from the attractive force
of the nucleus, therefore more shells means more reactivity.

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Transition Metals:
Hard, strong, dense and very high melting points (except mercury)
Not very reactive.
Form coloured compounds.
They form ions with different charges.
They are important catalysts in industry.
Group 7: Halogens:
Non metals.
They react with metals to produce ionic salts, ions with a 1- charge.
They react with other non metals to form molecules with covalent bonds.
All have coloured vapours and exist as diatomic molecules.
They are less reactive down the group.
Melting and boiling points increase down the group.…read more

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Part 2: Acids and Bases
Key words:
Acid: contains hydrogen ions (pH 6 ­ 1)
Alkali: contains hydroxide ions (pH 8 ­ 14)
Base: Something that neutralises an acid.
Strong / weak: Strong ionises in water, weak only partially ionises in water.
Ionisation:
Acids must be in solution to show their acidic properties, as they must be
ionised.
E.G:
Water
HCl (g) ----------> H+ (aq) + Cl- (ag)
Alkalis must also be in solution, they ionise to give hydroxide ions (OH-)
E.…read more

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The calculations:
1. Find the balanced equation to work out how many moles of acid
reacts with how many moles of alkali.
2. Use: Ma x Va = Mb x Vb.
3. Re-arrange the equation to calculate the answer:
Ma x Va
= Mb
e.g.
Vb
4. Multiply by the number of moles needed.
Try:
30cm3 of 1.0M HCl reacted with 25cm3 of NaOH. What was the
concentration of sodium hydroxide?
20cm3 of 1.0 M H3PO4 reacted with 25cm3 of NaOH.…read more

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Part 3: Aqueous Chemistry:
Condensation:
The energy It gets cooler as
from the sun the air rises
powers the Precipitation
whole
cycle.
Surface run
off- Snow melts
and this water
returns to the
sea.
Evaporation
from the sea Plant Uptake
and the soil Transpiration and
respiration release
water vapour
Key Words:
Solvent: A liquid that a solute can dissolve in.
Solution: A mixture of solute and solvent.
Solute: The solid that dissolves (or liquid).…read more

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Fizzy Drinks: as you release the pressure in the bottle by opening the cap
some of the carbon dioxide bubbles out.
Water Purification:
Drinking waters is purified by
physical and chemical
processes to remove solids,
bacteria and smell.
Hard water contains dissolved calcium and/or magnesium ions.…read more

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Or we can use an ion exchange column.
Hard Water:
Disadvantages Advantages
- Difficult to lather soap - Better taste
- Forms limescale and wastes - Health benefits of calcium
energy when you boil the kettle - Reduces heart illness
- Hot water pipes `fur up' - Better for making beer
- Leaves a scum which wastes - Limescale inside copper or lead
soap. pipes stops lead poisoning.
Some people filter their tap water.…read more

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Part 4: Energy:
When we compare fuels we can use a calorimeter to heat water using a fuel.
We measure the temperature change of the water, and the change in mass
of the fuel.
Energy per gram = energy released (J)
Mass of fuel used (g)
We know that it takes 4.2 joules of energy to heat 1 gram of water solution by
1 degree, so we can use this equation when heating water:
Energy = mass of water (g) x 4.…read more

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Bond energies
In this reaction there are 2 H-H bonds and 1 O=O bond. In the products there
are 4 H-O bonds.
An example equation:
these will
be given to
you if
necessary,
no need to
learn them,
it's just part
of the
example.…read more

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Part 5: Detection and Identification
Anions (negatively charged ions)
If you're having trouble remembering this think of electrolysis; the negative
ions go towards the anode (+) therefore they are anions.
Halides are tested by dissolving in dilute nitric acid and adding silver nitrate;
the results are as follows:
Halide Resulting precipitate
Chloride
White
Bromide
Cream
Iodide
Yellow
To test for sulphate; dissolve in HCL and add barium chloride to form a white
precipitate.
To test for nitrates; add NaOH and aluminium powder, then warm.…read more

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