14 Questions
What is the general formula for alkanes?
CₙH₂ₙ₊₂
What is the characteristic of saturated hydrocarbons?
They have only single carbon to carbon covalent bonds
What is the name of the C₅ alkane?
Pentane
What is the test to determine unsaturation in hydrocarbons?
Turn acidified KMnO₄ from pink to colourless
What is the structure and formula of cyclohexane?
C₆H₁₂, cyclohexane
Which of the following is an aromatic hydrocarbon?
Benzene
What is the formula of 2,2,4-trimethylpentane?
CH₃C(CH₃)₂CH₂CH(CH₃)CH₃
What is the general formula for alkenes?
CₙH₂ₙ
What is the shape of saturated hydrocarbons?
Tetrahedral
What is the name of the C₃ alkene?
Propene
What is the solubility of alkanes?
Soluble in cyclohexane but insoluble in water
What is the characteristic of cyclohexane?
It is a non-polar solvent
What is the general formula for alkynes?
CₙH₂ₙ₋₂
What is the name of the C₂ alkyne?
Ethyne
Study Notes
Hydrocarbons
- Hydrocarbons are compounds consisting of hydrogen and carbon only, bonded together covalently.
- They are commonly used as fuels.
- Examples include crude oil, methane, alkanes, alkenes, and alkynes.
Classification of Hydrocarbons
- Aliphatic hydrocarbons: consist of chains of carbon or certain rings of carbon.
- Aromatic hydrocarbons: include a benzene ring in their structure.
Cyclohexane
- Cyclohexane is a saturated compound containing only C – C bonds.
- It is an important non-polar solvent.
- Despite having polar C-H bonds, it is non-polar overall due to symmetry.
- Non-polar solutes will dissolve in non-polar solvents.
- Its structural formula is C6H12.
Saturated and Unsaturated Hydrocarbons
- Saturated hydrocarbons: have only single carbon to carbon covalent bonds.
- Unsaturated hydrocarbons: contain at least one carbon to carbon double or triple bond.
- Test for unsaturation: Turn acidified KMnO4 from pink to colorless, or decolourise red/brown bromine water.
Homologous Series
- A homologous series is a family of organic compounds with the same general formula, similar chemical properties, and successive members differing by CH2.
- Examples include alkanes, alkenes, and alkynes.
Alkanes
- General formula: CnH2n+2.
- Bond type: C - C.
- Solubility: Alkanes are non-polar, soluble in cyclohexane, and insoluble in water.
- Examples: C1 → C4 are gases, C5 → C15 are liquids, and ≥ C16 are waxy solids.
- Must know: names and structural formulas up to C8, structural isomers of C4 and C5.
Alkenes
- General formula: CnH2n.
- Bond type: C = C.
- Solubility: Alkenes are non-polar, soluble in cyclohexane, and insoluble in water.
- Examples: C2 → C4 are gases, and ≥ C5 are liquids or solids.
- Must know: names and structural formulas up to C4, structural isomers of C4.
Alkynes
- General formula: CnH2n-2.
- Bond type: C ≡ C.
- Solubility: Alkynes are non-polar, soluble in cyclohexane, and insoluble in water.
- Examples: C2H2 is a gas.
- Must know: names and structural formulas up to C2 alkyne, uses of C2 alkyne.
- Ethyne (C2H2): used in welding, burns in oxygen at approx. 3,000°C, has a sweetish scent, and burns in air with a sooty flame.
Learn about hydrocarbons, their composition, and classification into aliphatic and aromatic hydrocarbons. Understand the different types of hydrocarbons, including alkanes, alkenes, and alkynes.
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