OCR A-Level Chemistry: Chapter 12 -Alkanes
This flashcard set covers the essential properties of alkanes, including their primary use as fuels, their general molecular formula, and the nature of covalent bonding. It introduces sigma bonds as the fundamental bonding type in these saturated hydrocarbons.
What is the main use of alkanes?
Fuel
Key Terms
What is the main use of alkanes?
Fuel
What is the general formula of alkanes?
CnH2n+2
What kind of covalent bonds are formed in alkanes?
Sigma bonds
What is a sigma bond?
The overlap of two orbitals
How are alkanes separated?
Fractional distillation
How does chain length effect boiling point?
Longer chain length raises boiling point
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| Term | Definition |
|---|---|
What is the main use of alkanes? | Fuel |
What is the general formula of alkanes? | CnH2n+2 |
What kind of covalent bonds are formed in alkanes? | Sigma bonds |
What is a sigma bond? | The overlap of two orbitals |
How are alkanes separated? | Fractional distillation |
How does chain length effect boiling point? | Longer chain length raises boiling point |
Why does chain length have that effect on boiling point? | Increased chain length |
What is the effect of branching on boiling point? | Lowers boiling point |
Why does branching have that effect on boiling point? | More branching |
What are the reasons for alkanes being fairly unreactive? | C-C and C-H sigma bonds are strong |
| Alkane + oxygen -> water + carbon dioxide |
What is complete combustion? | Alkanes burn completely to produce carbon dioxide and water. |
What are the two potential products from incomplete combustion of alkanes? | Carbon monoxide Carbon |
What is the name of the mechanism for bromination of alkanes? | Free radical substitution |
What are the three stages of radical substitution? | Initiation |
Describe the initiation stage of radical substitution | Covalent bond in a bromine molecule is broken by homolytic fission. |
Describe the propagation stage of radical substitution | Two propagation steps: |
Describe the termination stage of radical substitution | Two radicals collide forming a molecule with all electrons paired. |
What can occur after a radical substitution reaction? | Further substitution |