USES OF PVC and Nylon

 •USES OF PVC:

PVC or polyvinyl chloride, is a type of plastic used in numerous industries. It is durable, inexpensive and resistant to heat, water and chemicals.

*PVC plastic is manipulated to create a leather-like material called Rexine.

*PVC are used for pipes. These pipes are strong, light weight and less reactive.

*PVC plastic is used to form the insulating material on electrical wires.

*PVC is used to manufacture bottles.

* Other uses of PVC include medical tubing, PVC window frames, flexible packaging, blood bags, resilient flooring, vinyl paneling, drainage pipes, gramophones records, carpet backing, etc.

• USES OF NYLON:

Nylon is a versatile and incredibly useful material.

*Stockings_nylons strong fibres can be woven together to produce a lightweight silky fibre that is perfect for stockings.

*Parachutes-nylon is used in the manufacture of parachutes.

*Tents and camping equipment_ durability and resistance make nylon a great choice for all kinds of camping equipments.

*Boating and sailing_ nylon is used in the production of many sails and ropes.

*Nylon is used in moulded machine parts such as gears and bearings.

Lipstic and its composition

 LIPSTICK:

Lipstick are basically dispersions of colouring matter in a base containing a suitable blend of oils, fats and waxes suitably perfumed, flavoured and moulded in the form of stick and enclosed in a case. Some lipsticks are also lip balm, to add colour and hydration.

•CHEMICAL COMPOSITION OF LIPSTICKS:

The chemical composition of lipstick varies greatly. The general composition of lipsticks are;

*A mixture of non volatile oils,e.g. caster, vegetable, mineral or wool fat, lanolin oil.

*Mixture of waxes, e.g. bee wnax or carnauba.

* Colours

*Antioxidants

*Preservatives

Usually perfumes are also added in very small quantity to combat the unpleasant fatty odour of the oil. 

The oil makes the wax-based product soft and to be easily applied.

 In order to reduce the 'stickness', usually, esters of fatty acids (like 2-propyl myristate) is also added. 

Lipsticks are made from hydrophobic materials.

 The dyes are water_insoluble. 

Water soluble dyes such as green or blue food dyes can be used to provide lipstick colouration but they are, first combined with metal oxides such as aluminium hydroxide,Al(OH)3, to form an insoluble precipitate 

It is then suspended in the oil base of the lipstick.

 

Colour is a key ingredient of lipsticks.

 Silicones and oily material are also added to reflect light and provide shine.

Measurement of viscosity:

General principle:

     The measurement of viscosity of liquid is based on pioseulle's equation.

               n=πPtr^4/8VI

Where:

   V= volume of liquid

    r= radius of capillary tube

    l= length of tube

   P= pressure applied

Measurement of absolute viscosity:

 It is difficult to measure  directly the exact value of absolute viscosity because measurement of p,r and v is difficult.

So the viscosities of liquids are expressed in relative term

relative viscosity:

          "This is the ratio of viscosity of liquid to the viscosity of water taken as reference standard and this is called relative viscosity.

OSTWALD's VISCOMETER (measurment of relative viscosity):

It is used to measure the relative viscosity.

• It is a U- shaped glass tube with two marks 'x'&'y'.

•It has two bulbs 'A' and 'B'.

•The bulb A is at higher level than B.

•A definite volume of liquid is put in bulb B and then sucked in bulb A.

•The time of flow of liquid is noted .Similarly the time of flow of reference liquid water is also noted.

•Density of liquid is determined by "Specific gravity bottle".

•Follow8ng equation is applied to calculate Viscosity.

       n°/n= d°/d × t°/t

Where:

n°= viscosity of liquid

 n= viscosity of relative liquid

d°= density of liquid determined by Specific gravity bottle

d=density of reference liquid

t°=time of flow of liquid

t= time of flow of reference liquid

Viscosity and fludity

Defination:

    "Liquid's resistance to flow".

                      OR

    " The frictional effect between different layers of a flowing fluid ".

Explanation:

It is the property which opposes the relative motion of adjacent layers of liquid. 

The substances that cannot flow easily have large coefficient of viscosity. (such as honey)whereas the substances that can flow easily have small coefficient of viscosity (Such as water).

Factors:

It depends upon: 

•The strength of Intermolecular force 

•Structure of the compound

•Shape of the molecule

The force which is required to maintain the steady flow of liquid in direction of the force is directly proportional to the viscosity gradient which is normal to the direction of flow. 

Defination:

   "It is the force per unit area , needed to maintain unit difference of velocity between two parallel layers of the liquid , unit distance apart." 

Unit of viscosity "poise":

"When  a force of one dyne per square cm is maintained, between two layers which are 1cm apart and the difference of velocity between the two layers is 1cm per second, then it is called poise. "

           1poise =10^-1 kg m^-1 s^-1

            1 centipoise =10^-2 poise

            1 millipoise =10^-3 poise

Effect of temperature on viscosity:

   The viscosity of a liquid falls with the increase in temperature.

It is estimated that for each one degree rise of temperature, there is 2% decrease of viscosity.

Fluidity:

       " Fluidity is the reciprocal of viscosity".

The units of fluidity are reciprocal of viscosity.(poise^-1).

Metallurgy of copper

 *~Metallurgy of copper..~*

Occurrence 

(a) sulphide ores ..

Copper pyrite or chalcopyrite 

Copper glance or chalcocite

Bornite or peacock ore

(b) oxide ores..

Cuprite 

Malachite

Melaconite

Native copper crystallizes in the cubic system .In Pakistan copper ores are found in north waziristan agency, chitral state.. etc

Extraction of copper from sulphite ores:

Large amount of copper 75% are obtained from copper pyrite by smelting . Ores containing 4% or more of copper are treated by smelting process.

1- smelting 

In this process the concentrated sulphide ores is oxidized by air . Sulphur burns to so2 , iron is converted to FeO which is removed as Fesio3.. following steps are involved

(a) concentration 

The finely crushed ore is concentrated by froth flotation process .The finely ground ore is suspended in water containing a little pine oil . A blast of air is passes through the suspension .

(b) Roasting

The concentrated ore is then roasted in a furnace in presense of ac current of air . Sulphur is oxidized to so2 and the impurities of arsenous and antimony are removed as volatile oxide .

(c) smelting 

The ore is now transferred into a water blast furnace . A little coke and sans are also added . The furnace is provided at the base with a row of twyers for the supply of air . The combustion of Orr itself provides a lot of heat and there fore less amount of coke are usually needed .

The iron and other silicates rise to the top and are removed as slav . A mixture of Cu2S and some unreacted Fess forms the lower layer and is called matte.

(d) Bessemerization 

The matte is removed in a Bessemer converter by blowing the air through the molten material. Fess is first oxidized to FeO and So 2 . Sand is added to remove FeO as FeSiO3 . The blast of air converts to metallic copper.

The copper obtained through Bessemerization has characteristics appearance due to evolution of gases from within and is called blister copper . Blister copper is about 98% pure copper .

2- Hydrometallurgical process..

The low grade sulphite ores of copper are subjected to Hydrometallurgical process . The crushed ore is bulk is allowed to whether in contact with water . Water is also allowed to percolate from the top . After about one year copper sulphide is oxidized to CuSO4 . At the same time FeSO4 and H2SO4 are also formed .

Uses:

1- copper is extensively used in preparing water stills , vaccum pans, steam coils , etc

2- copper is used in electrical equipment due to its high electrical conductivity.

3- large quantities of copper are used for the fireboxes of locomotive boilers. 

4- copper forms a large number of usesful alloys, brass, bronze, Monel metal German silver etc..

APPLICATIONS OF HYDROGEN BONDING

 APPLICATIONS OF HYDROGEN BONDING:

•Thermodynamic properties:

Hydrides of group 4 have lower points than that of group 5,6 and 7 because these hydrides are non polar and have only London dispersion forces among their molecules while group 5A,6A,and 7A have polar molecules which have dipole dipole forces.

•Solubility of hydrogen bonded molecules:

The compounds that have hydrogen bonds are soluble in each other. Ethyl alcohol and low mass carboxylic Acids can dissolve in water because of hydrogen bonds. Oil is insoluble because of no attraction.

• Cleansing action:

Soaps and detergents perform the cleansing action. Their polar parts are water soluble due to hydrogen bonding and non polar part dissolve oil or grease. Attraction between water and polar end of soap molecule carries the oil or grease droplet into the water.

• Hydrogen bonding in paints and dyes:

Paints and dyes have adhesive action due to hydrogen bonding. Similarly hydrogen bonding also makes glue and honey sticky substances.

• Clothing:

The rigidity and tensile strength of the cotton, silk and synthetic fibres are due to hydrogen bonding. Hydrogen bonding is of great importance in thread making materials.

• Food materials:

Food materials like carbohydrates consists of glucose, fructose, sucrose, each of them contains -OH groups which are responsible for hydrogen bonding in them.

HYDROGEN BONDING:

 HYDROGEN BONDING:

•Definition:

Hydrogen bond is the attraction between the lone pair of an electronegative atom and a hydrogen atom that is bonded to N,O,or F.

• Example:

Hydrogen bonding is present in NH3, H2O, HF, alcohols and carboxylic acids etc.

• Explanation:

Which one of them have higher boiling point.H2O OR H2S?

The boiling point and heat of vapourization of water are higher than those of H2S because H2O molecules attract each other through H-bonding whereas H2S molecules attract each other by dipole-dipole interactions.

• Limitation:

Hydrogen bonding is mainly limited to participation of nitrogen, oxygen and flourine atom.

• Strength of hydrogen bond:

Hydrogen bonds are stronger than London dispersion forces. Increasing order of strength of attractive forces is;

London dispersion force<dipole-dipole<H-bonding<Covalent bond.