author

Pankaj

teacher | Physics Chemistry Maths

Description

Hi, myself pankaj an M.Sc mathematics post graduate having more than 6+ years of experience in teaching ranging from class V-XII standard. I teach science, Maths, Physics and Chemistry and Biology.

Qualification

M.Sc

Experience

5-7 Years

Teaching Classes

11-12

Current Organization

Colloids, Classifications and Examples of each phases

Colloids is a mixture in which one substance is divided into small particles called colloidal particles and dispersed throughout a second substance. The substances are present as larger particles than those found in solution, but are too small to be seen with a microscope.

Colloid particles themselves are called Dispersed phase. Three forms in which all matter exists are solid, liquid or gas. Colloidal systems can be any combination of these states.

The medium in which colloidal particles are suspended/dispersed/distributed is called Dispersion Medium.

Classification and examples of colloids:

Medium/Phase

Dispersed phase

Gas

Liquid

Solid

Dispersion Medium

Gas

No such colloids are known
Helium and xenon are known to be immiscible under certain conditions.

Liquid aerosol
Examples: fog, clouds, mist, hair sprays

Solid aerosol
Examples: smoke, ice cloud, atmospheric particulate matter

Liquid

Foam
Example: whipped cream, shaving cream

Emulsion
Examples: milk, mayonnaise, hand cream; latex

Sol
Examples: milk (protein fraction), pigmented ink, blood

Solid

Solid foam
Examples: aerogel, styrofoam

Gel
Examples: agar, gelatin, jelly

Solid sol
Example: cranberry glass

 

Alkene - Properties, Nomenclature, Reaction, Isomers, Synthesis

Properties: Similar to alkane; non-polar, flammable

 

Nomenclature:

 

C=C; cumulative -C=C=C-

 

• Polyunsaturated fatty acid: 2 or more C=C

 

• Allene: adjacent C=C=C

 

• Vinyl group: H2C=CH-

 

• Methylene group: H2C=

 

• Allyl group: H2C=CH-CH2-

 

• Vinyl halide: halide replaces -H on >C=C<

 

• Conjugated: alternate C-C and C=C (resonance)

 

• Alkadiene, 2 conjugated C=C; example: butadiene;

s-cis and s-trans (rotate about C-C bond)

 

• Alkatriene, 3 conjugated C=C

 

• Annulene: conjugated monocyclic compound;

example: [6] annulene = benzene

 

• Aromatic cyclic ions: cyclopentadiene anion,

cycloheptatriene cation (6 electrons)

 

• Add -ene to prefix; Use # to denote C=C position

 

• Isolated C-C=C-C-

 

Isomers:

no free rotation of C=C

 

• E/Z; prioritize groups by atomic weight (Z - higher

priority groups on the same side)

 

• For noncyclic: cis is less stable (steric hindrance).

For cyclic, cis more stable.

 

• Hofmann Rule: Form the least-substituted alkene

 

• Markovnikof Addition: H adds to C with most -H’s

 

• Zaitsev Elimination: Form alkene with more

 

 

Synthesis:

 

• Dehydrate alcohol (H+, heat) (elimination)

 

• Dehydrohalogenate haloalkane (base, heat)

 

• Dehalogenate vic dihalide (Zn, acetic acid)

 

• Hydrogenate alkyne:

 

• syn, Z/cis-isomer (H2,P-2 catalyst)

 

• anti, E/trans-isomer (Li, NH3, -78 ̊C)

 

• Wittig, aldehyde/ketone + phosphorous ylide

 

Reaction:

 

• Combustion (O2)

 

• Hydrate to 2 ̊/3 ̊ alcohol (H+, H2O); 1 ̊ from ethene;

can rearrange (Markovnikov)

 

• Hydrate to alcohol; hydroborate/oxidize

(THF/B2H6,H2O2/OH-) (syn, anti-Markovnikov)

 

• Oxymercurate-demercurate to alcohol

 

• Hydrohalogenate (HX) (Markovnikov)

 

• Halogenate (Br2/Cl2), vic dihaloalkane (X2,CCl4; anti)

• Halohydrin (X2, H2O; anti-addition)

 

• Hydroxylate to form a 1,2-diol (KMnO4, cold OH-syn addition)

• Oxidize to carboxylic acid (KMnO4, hot OH-)

 

• Ozonolyze to ketone (O3; Zn, H2O)

 

• Hydrogenate to alkane (Pt, H2; syn-addition)

 

• Free radical polymerization

 

• Alkadiene Reaction

 

• allylic halogenation (Cl2, heat)

 

• Diels-Alder: cycloalkene from diene + alkene/alkyne

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