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Chemistry - Organic Chemistry

Grade 10ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

Catenation: The unique property of the Carbon atom to form direct bonds with other carbon atoms, resulting in long chains, branched chains, or closed rings. This allows for the vast variety of organic compounds.

Tetravalency: Carbon has a valency of 44, meaning it can form four covalent bonds with other atoms like HH, OO, NN, and halogens to achieve stability.

Homologous Series: A group of organic compounds having the same general formula and functional group, where successive members differ by a CH2-CH_2- group and a molecular mass of 1414 u.

Functional Groups: An atom or group of atoms that defines the chemical properties of an organic compound. Examples include the Hydroxyl group (OH-OH), Aldehyde group (CHO-CHO), and Carboxylic acid group (COOH-COOH).

Isomerism: The phenomenon where compounds have the same molecular formula but different structural arrangements of atoms. Common types in ICSE include Chain Isomerism (e.g., Butane and Iso-butane) and Position Isomerism (e.g., 11-propanol and 22-propanol).

Saturated Hydrocarbons (Alkanes): Hydrocarbons containing only single carbon-carbon bonds (CCC-C). They undergo Substitution Reactions.

Unsaturated Hydrocarbons (Alkenes and Alkynes): Hydrocarbons containing at least one double (C=CC=C) or triple (CCC\equiv C) bond. They are more reactive than alkanes and undergo Addition Reactions.

Nomenclature: Following IUPAC rules, the name consists of a Root Word (number of C atoms), a Primary Suffix (saturation level), and a Secondary Suffix (functional group).

📐Formulae

General Formula of Alkanes: CnH2n+2\text{General Formula of Alkanes: } C_n H_{2n+2}

General Formula of Alkenes: CnH2n\text{General Formula of Alkenes: } C_n H_{2n}

General Formula of Alkynes: CnH2n2\text{General Formula of Alkynes: } C_n H_{2n-2}

General Formula of Alkyl Groups: CnH2n+1\text{General Formula of Alkyl Groups: } C_n H_{2n+1}

General Formula of Alcohols: CnH2n+1OH\text{General Formula of Alcohols: } C_n H_{2n+1}OH

Preparation of Methane (Soda Lime): CH3COONa+NaOHCaO,ΔNa2CO3+CH4\text{Preparation of Methane (Soda Lime): } CH_3COONa + NaOH \xrightarrow{CaO, \Delta} Na_2CO_3 + CH_4 \uparrow

Combustion of Methane: CH4+2O2CO2+2H2O+Heat\text{Combustion of Methane: } CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O + \text{Heat}

Addition Reaction (Ethyne to Ethene): C2H2+H2Ni,200CC2H4\text{Addition Reaction (Ethyne to Ethene): } C_2H_2 + H_2 \xrightarrow{Ni, 200^{\circ}C} C_2H_4

💡Examples

Problem 1:

Give the IUPAC name for the compound: CH3CH(CH3)CH2OHCH_3-CH(CH_3)-CH_2-OH.

Solution:

2-methylpropan-1-ol2\text{-methylpropan-1-ol}

Explanation:

  1. Identify the longest chain containing the functional group (OH-OH): 33 carbons \rightarrow Propanol. 2. Number the chain from the end closest to the OH-OH group. 3. Identify the substituent: a methyl group (CH3-CH_3) is at position 22. Hence, 2-methylpropan-1-ol2\text{-methylpropan-1-ol}.

Problem 2:

Write the balanced chemical equation for the reaction of Ethene (C2H4C_2H_4) with Bromine solution (Br2Br_2 in CCl4CCl_4).

Solution:

C2H4+Br2CCl4C2H4Br2C_2H_4 + Br_2 \xrightarrow{CCl_4} C_2H_4Br_2

Explanation:

This is an addition reaction where the double bond in Ethene breaks to accommodate two bromine atoms, forming 1,2-dibromoethane1,2\text{-dibromoethane}. The reddish-brown color of bromine is discharged, serving as a test for unsaturation.

Problem 3:

How do you distinguish between Ethane and Ethene using a chemical test?

Solution:

Use Bromine water test or Alkaline KMnO4KMnO_4 (Baeyer's Reagent).

Explanation:

Ethane (Alkane) does not react with Bromine water under normal conditions (no color change). Ethene (Alkene) decolourises the reddish-brown Bromine water due to the formation of 1,2-dibromoethane1,2\text{-dibromoethane} through an addition reaction.