Basic Concepts.

These cards can be used for revising the F322 topic basic concepts.

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  • Created by: Bethany
  • Created on: 12-01-12 19:06

Percentage Yield.

A perfectly efficient reaction would convert all starting reactants to products giving 100% yield.

Incomplete reactions occur because:

  • reaction may be incomplete.
  • there may be side reactions.
  • some product is lost during transfer.

Percentage yield= actual yield(mol)   X 100

                             theoretical yield

Actual yield: mass of product obtained from a reaction.

Theoretical yield: maximum amount of product assuming the reaction goes by equation.

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Atom Economy.

Considers the by product of a reaction as well as the desired product.

By products are considered as waste but sometimes can be sold or recycled in the reaction.

A reaction with high atom economy has minimal waste, leading to less environmental waste.

Atom economy= molecular mass of desired products X 100

                         sum of molecular mass of all products

Addition reactions have an atom economy of 100%

Substitution and elimination reactions have an atom economy less than 100%

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Structural Isomerism.

Compounds with the same molecular formulae but a different structural formulae.

Chain Isomerism: hydrocarbon chain may be straight or branched.

Functional Isomerism: hydrocarbons with the same molecular formulae but different functional groups.

Positional Isomerism: isomers have the same functional groups but with different positions in the carbon chain.

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Sterioisomerism: componds with the same molecular formulae, however with a different arrangement of atoms in space.

E/Z isomerism.

Two criteria:

  • C=C double bond must be present (cannot be twisted)
  • each carbon in the double bond must be attached to two different groups.

Labelled with E when two moelcules with the biggest molecular masses are opposite.

Labelled with Z when when two moelcules with the biggest molecular masses are on the same side.

Cis/Trans isomerism.

Two criteria.

  • there must be two different groups on each carbon of the C=C bond.
  • two of these groups must be the same.

The cis isomer has the same group on the same side of the C=C bond.

The trans isomer has the same group opposite to eachother.

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