Chemistry C7 OCR 21st Century

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C7 ­ Further Chemistry
C7.1 Green chemistry
The chemical industry synthesises chemicals on different scales according to their value:
Bulk chemicals are made on a larger scale, for example:
Sulfuric acid
Sodium hydroxide
Phosphoric acid
Fine chemicals are made on a small scale, for example:
Food additives
A large proportion of the people employed in chemical industry work in research and development.
Developing new chemical products or processes ­ such as new catalysts for industrial reaction ­
requires an extensive programme of research and development.
The government has a duty to protect people working in the chemical industry and also to protect
the consumers and the environment from any dangers that could occur as a result of procedures
involving chemicals. They impose strict regulations in order to control:
Chemical processes
The storage of chemicals
The transportation of chemicals
The research and development of chemicals
The production of useful chemicals involves several stages including:
Preparation of feedstock
Separation of products
Handling of by-products and wastes
Monitoring purity
Green chemistry is a term that is used to describe a set of principles that can help to make the
production of a chemical more sustainable

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The sustainability of a process depends on:
Whether or not the feedstock is renewable
Atom economy ­ the final product should aim to contain all the atoms used in the process,
thereby reducing waste products and increasing the yield
Atom economy =Mass
of atoms in the useful product
of atoms in the reactants ×100
By-products or waste ­ whether there are a lot of waste products (or by-products) and whether
they can be recycled, used for something else or are hazardous
Energy inputs or…read more

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To calculate a reactants mass:
Steps Example ­ Find the mass of Zn that can be
extracted from 100g of ZnO
Write down the formula The formula is ZnO
Work out the relative formula mass RFM is 65+16 = 81
RAM of Zn
Work out the percentage mass of metal in the RFM of Zno x 100 = 80%
formula In 100g there will be 10080 x 100 = 80g of Zn
Work out the mass of metal
C7.…read more

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Alkanes do not react with aqueous reagents because C-C and C-H bonds are difficult to break and
are therefore unreactive.
However alkanes tend to burn well in plenty of air to produce carbon dioxide and water. For
Propane + Oxygen Carbon Dioxide + Water
C3H8 + 5O2 3CO2 +4H2O
Some groups of hydrocarbons e.g. the alkenes are more reactive than the alkanes because they
contain a reactive carbon-carbon double bond (C=C) ­ alkenes are unsaturated hydrocarbons.…read more

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Ethanol + Oxygen Carbon Dioxide + Water
C2H5OH + 3O2 2CO2 + 3H2O
Alcohols react with sodium to produce a salt and hydrogen gas ­ it is the presence of the functional
group ­OH that allows this reaction to occur:
Ethanol + Sodium Sodium Ethoxide + Hydrogen
2C2H5OH + Na 2C2H5O-Na+ + H2
Because alkanes do not react with sodium it is unlikely to be the carbon chain in the alcohol that is
causing this reaction to take place
On the other hand, water reacts…read more

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Ethene is reacted with steam at high
temperatures and in the presence of a
phosphoric acid catalyst
Any unreacted ethane and steam are
recycled back into the process so that they
are not wasted
Carboxylic acids form a homologous series with the functional group ­COOH ­ the presence of
the -COOH group gives carboxylic acids their characteristic properties
The general formula of carboxylic acids are CH2n+1COOH
Carboxylic acid Molecular formula Structural formula Ball-and-stick model
Methanoic acid HCOOH
Ethanoic acid CH3COOH
Vinegar is a dilute solution…read more

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Ethanoic Acid + Sodium Hydroxide Sodium Ethanoate + Water
Reaction of a carboxylic acid with a carbonate:
Acid + Metal Carbonate Salt + Water + Carbon Dioxide
Ethanoic Acid + Calcium Carbonate Calcium Ethanoate + Water + Carbon Dioxide
Esters are formed when a carboxylic acid reacts with an alcohol in the presence of a strong acid
catalyst ­ the general word equation is:
Carboxylic Acid + Alcohol Ester + Water
E.g.…read more

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The mixture will react with any remaining substance containing no water) calcium chloride
acid and extract it into the aqueous phase ­ the is added to remove any remaining water
aqueous phase is then run off leaving the ester in molecules ­ the calcium chloride is removed
the funnel later by filtiration
Fats and oils are naturally-occurring esters of glycerol (an alcohol with three ­OH groups) and fatty
acids (carboxylic acids with very long hydrocarbon chains.…read more

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Breaking a chemical bond requires a lot of energy ­ endothermic process
In a chemical reaction, new substances are produced ­ in order for this to happen, the bonds in the
reactants must be broken and new bonds made to form the products.
The activation energy is the energy needed to start a reaction i.e.…read more

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Some chemical reactions are reversible, i.e. the products can react together to produce the original
reactions. In an equation shows that the reaction can go in either the forward or reverse
direction depending on the conditions
A reversible reaction will reach a state of equilibrium if it is in a closed system
Once equilibrium is achieved, the concentration of the reactants and products does not change ­ the
equilibrium can be approached from either direction i.e. the `reactant' side or the `product' side.…read more


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