Nota Chemistry Tingkatan 5 Bab 2

2.1 Types of Carbon Compounds

Carbon compounds are compounds containing carbon as an essential element.

Organic Compounds: Compounds originating from living things that contain carbon bonded covalently to hydrogen, oxygen, nitrogen, or halogen elements (e.g., glucose, ethanol).
Inorganic Compounds: Compounds containing carbon not originating from living things (e.g., carbon dioxide $\text{CO}_2$, carbonates $\text{CaCO}_3$).
Hydrocarbons: Organic compounds composed only of carbon ($\text{C}$) and hydrogen ($\text{H}$) atoms.
Saturated Hydrocarbons: Hydrocarbons containing only single covalent bonds ($\text{C}-\text{C}$) between carbon atoms (e.g., alkanes).
Unsaturated Hydrocarbons: Hydrocarbons containing at least one double bond ($\text{C}=\text{C}$) or triple bond ($\text{C}\equiv\text{C}$) between carbon atoms (e.g., alkenes, alkynes).

A homologous series is a family of organic compounds with similar chemical properties that meet specific criteria:

Represented by a general formula.
Successive members differ by a $-\text{CH}_2-$ unit (relative molecular mass increases by 14).
Same functional group (determines chemical properties).
Gradual transition in physical properties (boiling point increases as molecular size increases).

Alkane: General formula $\text{C}_n\text{H}_{2n+2}$ ($n=1,2,3...$). Functional group: Single bond ($\text{C}-\text{C}$).
Alkene: General formula $\text{C}_n\text{H}_{2n}$ ($n=2,3,4...$). Functional group: Carbon-carbon double bond ($\text{C}=\text{C}$).
Alkyne: General formula $\text{C}_n\text{H}_{2n-2}$ ($n=2,3,4...$). Functional group: Carbon-carbon triple bond ($\text{C}\equiv\text{C}$).
Alcohol: General formula $\text{C}_n\text{H}_{2n+1}\text{OH}$ ($n=1,2,3...$). Functional group: Hydroxyl group ($-\text{OH}$).
Carboxylic Acid: General formula $\text{C}_n\text{H}_{2n+1}\text{COOH}$ ($n=0,1,2...$). Functional group: Carboxyl group ($-\text{COOH}$).
Ester: General formula $\text{C}_n\text{H}_{2n+1}\text{COOC}_m\text{H}_{2m+1}$. Functional group: Carboalkoxy group ($-\text{COO}-$).

Relatively unreactive (inert) due to strong non-polar single bonds.
Combustion: Complete combustion yields $\text{CO}_2$ and $\text{H}_2\text{O}$.
Substitution Reaction: Reacts with halogens (e.g., $\text{Cl}_2$) in the presence of ultraviolet (UV) light.

More reactive than alkanes due to the presence of the reactive double bond ($\text{C}=\text{C}$). Undergoes addition reactions:

Addition of Hydrogenation: Reacts with $\text{H}_2$ at $180^\circ\text{C}$ using a Nickel ($\text{Ni}$) catalyst to produce an alkane.
Addition of Halogenation: Decolorises reddish-brown bromine water ($\text{Br}_2$) without sunlight (Distinguishing test from alkanes).
Addition of Water (Hydration): Reacts with steam ($\text{H}_2\text{O}$) at $300^\circ\text{C}$, $60\text{ atm}$ using $\text{H}_3\text{PO}_4$ catalyst to produce alcohol.
Oxidation: Decolorises purple acidified potassium permanganate ($\text{KMnO}_4$) solution to produce a diol.

Preparation of Ethanol: Fermentation of glucose using yeast at room temperature ($37^\circ\text{C}$) in anaerobic conditions.
Oxidation: Refluxed with acidified $\text{K}_2\text{Cr}_2\text{O}_7$ or acidified $\text{KMnO}_4$ to form a carboxylic acid (orange $\text{K}_2\text{Cr}_2\text{O}_7$ turns green).
Dehydration: Passed over heated porcelain chips or concentrated $\text{H}_2\text{SO}_4$ to form an alkene and water.

Weak monoprotic organic acids (turn blue litmus paper red).
React with reactive metals to liberate $\text{H}_2$ gas, and react with carbonates ($\text{CaCO}_3$) to liberate $\text{CO}_2$ gas.

Esterification Reaction: Carboxylic Acid + Alcohol $\rightleftharpoons$ Ester + Water (in the presence of concentrated $\text{H}_2\text{SO}_4$ as catalyst).
Properties: Sweet fruity smell, neutral, insoluble in water, less dense than water.

Isomers are molecules that have the same molecular formula but different structural formulas.

Alkanes display structural isomerism starting from butane ($\text{C}_4\text{H}_{10}$).
Alkenes display isomerism starting from propene or butene ($\text{C}_4\text{H}_8$), considering chain and position of double bond.
Isomers possess identical relative molecular mass but differing physical properties (e.g., branched isomers have lower boiling points due to smaller surface contact area).