Alkanes from Crude Oil
This OCR section does not examine crude oil, fractional distillation, cracking or reforming. Cracking appears later only as a source of alkenes.
Revision Notes
3 revision notes, in the order the specification teaches them.
Fractional Distillation
Revise how crude oil is separated into fractions using differences in boiling point and chain length.
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Cracking
Learn how long-chain hydrocarbons are broken into shorter alkanes and alkenes that are more useful as fuels and feedstocks.
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Reforming
Review how straight-chain hydrocarbons are rearranged into branched or cyclic molecules to improve fuel quality.
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Alkanes Map
OCR A Level Chemistry A · 4.1.2 Alkanes
Every reaction on one A4 page: reagents, conditions and reaction type for each arrow, colour coded, with the key tests.
Alkanes Summary Map
OCR A Level Chemistry A · 4.1.2 Alkanes
The whole section on one A4 page: σ-bonds and free rotation, the tetrahedral carbon, boiling points, low reactivity, combustion and carbon monoxide, with radical substitution and its limits in a table.
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Specification
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4.1.2
- a i
alkanes as saturated hydrocarbons containing single C–C and C–H bonds as σ-bonds (overlap of orbitals directly between the bonding atoms)
Revise - b i
explanation of the tetrahedral shape around each carbon atom in alkanes in terms of electron pair repulsion (see also 2.2.2 g–h)
Revise - b ii
explanation of the bond angle around each carbon atom in alkanes in terms of electron pair repulsion (see also 2.2.2 g–h)
Revise - c i
explanation of the variations in boiling points of alkanes with different carbon-chain length, in terms of induced dipole–dipole interactions (London forces) (see also 2.2.2 k)
Revise - c ii
explanation of the variations in boiling points of alkanes with different branching, in terms of induced dipole–dipole interactions (London forces) (see also 2.2.2 k)
Revise - d i
the low reactivity of alkanes with many reagents in terms of the high bond enthalpy of the σ-bonds present (see also 2.2.2 j)
Revise - d ii
the low reactivity of alkanes with many reagents in terms of the very low polarity of the σ-bonds present (see also 2.2.2 j)
Revise - f i
the reaction of alkanes with chlorine and bromine by radical substitution using ultraviolet radiation
Revise - f ii
the mechanism of radical substitution involving homolytic fission and radical reactions in terms of initiation (see also 4.1.1 f–g)
Revise - f iii
the mechanism of radical substitution involving homolytic fission and radical reactions in terms of propagation (see also 4.1.1 f–g)
Revise - f iv
the mechanism of radical substitution involving homolytic fission and radical reactions in terms of termination (see also 4.1.1 f–g)
Revise - g i
the limitations of radical substitution in synthesis by the formation of a mixture of organic products, in terms of further substitution
Revise - g ii
the limitations of radical substitution in synthesis by the formation of a mixture of organic products, in terms of reactions at different positions in a carbon chain
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