AQA Chemistry

Just some notes i made whilst revising some may be incomplete sorry. x

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  • Created on: 19-05-13 21:36
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Chemistry AQA C3
The early periodic table
Newlands periodic table
Law of octaves ­ noticed that every 8th element had similar properties
Mendeleev's table
Group 1 ­ Alkali metals
Low density
React with non-metals to form ionic compounds
React with water to produce hydrogen and hydroxide alkali solutions
The further down the group
- The more reactive the element
­ The lower the melting and boiling point.
The transition metals ­ between groups 2 3
Have melting and boiling points than group 1 except mercury
Are harder and stronger- good structural materials
Form ions with different charges
Form coloured compounds
Useful catalysts e.g Iron in the harber process
Group 7 ­ the halogens
Poor conductors ­ heat and electricity
Poisonous
Coloured vapours
React with metals to form ionic compounds ­ the ion produced is called a halide and has a
charge of -1
The further down the group
-the less reactive the element
- The higher the melting and boiling points.
The more reactive halogen can displace a less reactive one from an aqueous solution of
its salt.
All the halogens are diatomic
Reactivity explained
The higher the energy level of the outer electrons =
· The more easily the electrons are lost
· The less easily electrons are gained

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This is because
If the outer electron is further away from the nucleus than there is a weaker attraction to the
nucleus
Also there is MORE screening /shielding by inner electrons, so electron is easily lost.…read more

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Relative mole mass = 40g ­ placed it into 1000cm3 of water and have made a 1 mole per dm cubed
of NaOH
Put 40g in 5000cm of water
What is the concentration in moles/dm3
80g in 1000cm so 2moles/dm3
What is the mass of sodium hydroxide is there in 250 cm3 of 2 moles/dm3 of solution
So got 80g dm cubed so have a 80/4 = 20 g
ACID ALKALI
CON.C X VOLUME = CON.…read more

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Alcohols
Examples
Methanol
Ethanol
Propanol
Contain the functional group ­O-H
A homologous series
Methanol ­ CH3OH
Ethanol- CH3CH2OH
Propanol CH3CH2CH2OH
Key points
Dissolve in water to form a neutral solution
React with sodium to produce hydrogen
Burn in air ­ produces carbon dioxide and water
Ethanol can be oxidised to form ethanoic acid- main acid in vinegar
Its oxidised either by
Chemicals called oxidising agents…read more

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Or....
Microbes
Carbxylic acids
FUNCTIONAL GROUP ­COOH
Methanoic acid - HCOOH
Ethanoic acid CH3COOH
Propanoic acid CH3CH2COOH
Key features
Dissolve in water to produce acidic solutions
React with carbonates to produce carbon dioxide
React with alcohols and acid catalyst to make esters.…read more

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Don't ionise completely in water ­ weak acids
Aqueous solutions of carboxylic acids have a higher PH than aqueous solutions of strong acids
with the same concentration. ­ This is because the ionising in water of carboxylic acids is
revisable and therefore will be at equilibrium. ­ therefore will have a lower number of
hydrogen ions in solution.…read more

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Equilibrium- Reactions occur at the same rate in each direction.
Explanation for conditions
The yield of ammonia is only around 15
Ammonia is being produced at the same rate as hydrogen and nitrogen but want to encourage
forwarding reaction more to produce more ammonia
High pressure ­ Increase in pressure favours the direction of reaction that produces the
least number of molecules. The forward reaction only has 2 whereas the backwards
reaction has 4 molecules being produced.…read more

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Yellow ­ Sodium plus
Lilac ­potassium plus
Brick red ­ calcium 2 plus
Green- barium 2plus
Sodium Hydroxide
White precipitate-
Aluminium ­ if you add excess the precipitate dissolves
Calcium
Magnesium
Need a flame test to differentiate between the two.…read more

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This produces gasses which contribute to pollution
2 ways to use it
Combustion engine
Fuel cell ­ chemical reaction ­ produces electricity heat and water ­ the electricity is used to
power the car.…read more

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