Explain alkanoates. 2. State any three members of the alkanoate family. 3. Explain esterification. 4. Write a typical equation representing esterification. 5. Differentiate between polymerisation and condensation. What is the difference between alkalis and bases?

Chemistry
Explain alkanoates. 2. State any three members of the alkanoate family. 3. Explain esterification. 4. Write a typical equation representing esterification. 5. Differentiate between polymerisation and condensation. What is the difference between alkalis and bases?

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(1) Addition polymerization of alkenes

Addition polymerization of alkenes is a chain-growth process where multiple alkene molecules (monomers with C=C double bond) link together by opening the double bond, forming a long chain polymer without loss of any small molecule byproduct.

Typical mechanism: Free radical addition polymerization.

General reaction for ethene (a common alkene):

n CH2=CH2→initiator[−CH2−CH2−]nn \ CH_2=CH_2 \xrightarrow{initiator} \left[ -CH_2-CH_2- \right]_n

Steps:

  • Initiation: Peroxide initiator decomposes to radicals.
(R−O)2→2 R−O∙(R-O)_2 \rightarrow 2 \ R-O^\bullet R−O∙+CH2=CH2→R−O−CH2−CH2∙R-O^\bullet + CH_2=CH_2 \rightarrow R-O-CH_2-CH_2^\bullet
  • Propagation: Radical adds to monomer repeatedly.
R−O−(CH2−CH2)n∙+CH2=CH2→R−O−(CH2−CH2)n+1∙R-O-(CH_2-CH_2)_n ^\bullet + CH_2=CH_2 \rightarrow R-O-(CH_2-CH_2)_{n+1 ^\bullet}
  • Termination: Radicals combine.
R−O−(CH2−CH2)m∙+R−O−(CH2−CH2)p∙→R−O−(CH2−CH2)m+p−O−RR-O-(CH_2-CH_2)_m ^\bullet + R-O-(CH_2-CH_2)_p ^\bullet \rightarrow R-O-(CH_2-CH_2)_{m+p-O-R}

Three monomers (alkenes): Ethene (CH2=CH2\mathrm{CH_2=CH_2}), propene (CH2=CH−CH3\mathrm{CH_2=CH-CH_3}), but-1-ene (CH2=CH−CH2−CH3\mathrm{CH_2=CH-CH_2-CH_3}).

(2) Chain reaction representing typical homopolymer situation

Homopolymer: Polymer formed from one type of monomer only.

Typical situation: Free radical addition polymerization of an alkene (e.g., ethene to polyethylene).

Chain reaction has three main steps:

Initiation:

Peroxide decomposes:

Bz2O2→2 BzO∙(Bz=C6H5CH2)Bz_2O_2 \rightarrow 2 \ BzO^\bullet \quad (Bz = C_6H_5CH_2)

Radical adds to monomer:

BzO^\bullet + CH_2=CH_2 \rightarrow \mathrm{BzO-CH_2-CH_2^\bullet

Propagation:

BzO-CH_2-(CH_2-CH_2)_{n-1-CH_2 ^\bullet + CH_2=CH_2 \rightarrow BzO-CH_2-(CH_2-CH_2)_n -CH_2 ^\bullet

Termination (combination):

BzO-(CH_2-CH_2)_m ^\bullet + \mathrm{BzO-(CH_2-CH_2)_n ^\bullet \rightarrow BzO-(CH_2-CH_2)_{m+n-OBz}

This represents homopolymerization as only one monomer (ethene) is used.

(3) Difference between polymerization and condensation

| Polymerization (Addition) | Condensation | |-------------------------------|------------------| | Monomers link by addition across multiple bond (e.g., C=C). | Monomers link by elimination of small molecule (e.g., H2_2O). | | No byproduct. | Byproduct formed. | | Chain-growth, fast. | Step-growth, slower. | | Example: n CH2=CH2→[−CH2−CH2−]nn \ CH_2=CH_2 \rightarrow [-CH_2-CH_2-]_n (polyethene). | Example: HO-(CH2_2)4_4-OH + HOOC-(CH2_2)4_4-COOH →\rightarrow [-O-(CH2_2)4_4-OOC-(CH2_2)4_4-CO-]n_n + (2n-1) H2_2O (nylon 6,6). |

Difference between homopolymers and copolymers

Homopolymers: Formed from a single type of monomer. All repeating units identical.

Example: Polyethene [−CH2−CH2−]n[-CH_2-CH_2-]_n from ethene only.

Copolymers: Formed from two or more different monomers. Repeating units vary.

Example: Styrene-butadiene rubber (SBR): [-CH(CH3_3)-CH2_2-] from propene? Wait, styrene C6H5CH=CH2\mathrm{C_6H_5CH=CH_2} and buta-1,3-diene CH2=CH−CH=CH2\mathrm{CH_2=CH-CH=CH_2}.

Types of copolymers: Random, alternating, block, graft.

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(1) Addition polymerization of alkenes Addition polymerization of alkenes is a chain-growth process where multiple alkene molecules (monomers with C=C double bond) link together by opening the double bond, forming a long chain polymer without loss of…

Explain alkanoates. 2. State any three members of the alkanoate family. 3. Explain esterification. 4. Write a typical equation representing esterification. 5. Differentiate between polymerisation and condensation. What is the difference between alkalis and bases?
Chemistry

This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.

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(1) Addition polymerization of alkenes Addition polymerization of alkenes is a chain-growth process where multiple alkene molecules (monomers with C=C double bond) link together by opening the double bond, forming a long chain polymer without loss of any small molecule byproduct. Typical mechanism: Free radical addition polymerization. General reaction for ethene (a common alkene): n \ CH_2=CH_2 initiator [ -CH_2-CH_2- ]_n Steps: Initiation: Peroxide initiator decomposes to radicals. (R-O)_2 → 2 \ R-O^ R-O^ + CH_2=CH_2 → R-O-CH_2-CH_2^ Propagation: Radical adds to monomer repeatedly. R-O-(CH_2-CH_2)_n ^ + CH_2=CH_2 → R-O-(CH_2-CH_2)_n+1 ^ Termination: Radicals combine. R-O-(CH_2-CH_2)_m ^ + R-O-(CH_2-CH_2)_p ^ → R-O-(CH_2-CH_2)_m+p-O-R Three monomers (alkenes): Ethene (CH_2=CH_2), propene (CH_2=CH-CH_3), but-1-ene (CH_2=CH-CH_2-CH_3). (2) Chain reaction representing typical homopolymer situation Homopolymer: Polymer formed from one type of monomer only. Typical situation: Free radical addition polymerization of an alkene (e.g., ethene to polyethylene). Chain reaction has three main steps: Initiation: Peroxide decomposes: Bz_2O_2 → 2 \ BzO^ (Bz = C_6H_5CH_2) Radical adds to monomer: BzO^ + CH_2=CH_2 → BzO-CH_2-CH_2^ Propagation: BzO-CH_2-(CH_2-CH_2)_n-1-CH_2 ^ + CH_2=CH_2 → BzO-CH_2-(CH_2-CH_2)_n -CH_2 ^ Termination (combination): BzO-(CH_2-CH_2)_m ^ + BzO-(CH_2-CH_2)_n ^ → BzO-(CH_2-CH_2)_m+n-OBz This represents homopolymerization as only one monomer (ethene) is used. (3) Difference between polymerization and condensation | Polymerization (Addition) | Condensation | |-------------------------------|------------------| | Monomers link by addition across multiple bond (e.g., C=C). | Monomers link by elimination of small molecule (e.g., H_2O). | | No byproduct. | Byproduct formed. | | Chain-growth, fast. | Step-growth, slower. | | Example: n \ CH_2=CH_2 → [-CH_2-CH_2-]_n (polyethene). | Example: HO-(CH_2)_4-OH + HOOC-(CH_2)_4-COOH → [-O-(CH_2)_4-OOC-(CH_2)_4-CO-]_n + (2n-1) H_2O (nylon 6,6). | Difference between homopolymers and copolymers Homopolymers: Formed from a single type of monomer. All repeating units identical. Example: Polyethene [-CH_2-CH_2-]_n from ethene only. Copolymers: Formed from two or more different monomers. Repeating units vary. Example: Styrene-butadiene rubber (SBR): [-CH(CH_3)-CH_2-] from propene? Wait, styrene C_6H_5CH=CH_2 and buta-1,3-diene CH_2=CH-CH=CH_2. Types of copolymers: Random, alternating, block, graft. See above explanations