NCERT Summary - Man-Made Materials
Category : 8th Class
Man-Made Materials
Soaps
Differences between Soaps and Detergents
Soaps |
Detergents |
They are metallic salts of long chain higher fatty acids, |
These are sodium salts of long chain hydrocarbons like alky1 sulphates or alkyl benzene sulphonates. |
These are prepared from vegetable oils and animals fats. |
They are prepared from hydrocarbons of petroleum or coal. |
They cannot be used effectively in hard water as they produce scum, i.e., insoluble precipitates of \[C{{a}^{2+}},\] \[M{{g}^{2+}},\] \[F{{e}^{2+}},\] etc. |
These do not produce insoluble precipitates in hard water. They are effective in soft, hard or salt water. |
These cannot be used in acidic solutions. |
They can be used even in acidic solutions. |
Their cleansing action is not as strong as that of detergents, |
Their cleansing action is by surfactants, which is a strong cleansing action. |
These are biodegradable. |
Some of these are not biodegradable. |
Detergents
Fertilisers
Examples of Fertilisers, their Formula and the Essential Elements
Fertiliser |
Essential |
Acid |
Alkali |
Ammonium |
nitrogen |
nitric |
ammonia |
Ammonium phosphate |
Nitrogen and phosphorus |
Phosphoric acid |
ammonia |
Ammonium sulphate |
Nitrogen |
Sulphuric acid |
ammonia |
Potassium nitrate |
potassium and nitrogen |
nitric acid |
potassium hydroxide |
Glass
Type of Glass |
Special use |
Soft glass |
Ordinary glass for window panes, test tubes, bottles, etc. |
Hard glass |
For combustion tubes and chemical glassware |
High refractive index glass (Flint glass) |
For making lenses, cut glasses |
Pyrex glass |
For high quality glass apparatus, cooking utensils |
Crook's glass |
Absorbs ultraviolet rays, for making lenses |
Jena glass |
It is resistant to heat, shock and common reagent. It is used for making good quality glass wares. |
Glass Pigment
Compounds |
Colour |
Iron Oxides |
green, brown |
Manganese oxide |
deep amber, amethyst, decolouriser deep blue |
Gold chloride |
ruby red |
Selenium compounds |
red |
Carbon oxides |
amber/brown |
Mix of managanese, corblay, iron |
black |
Antimony oxides |
white |
Uranium oxides |
yellow green (glows) |
Sulphur compounds |
light blue, red |
Tin compounds |
white |
Lead with antimony |
yellow |
Portland Cement
Approximate Composition Limits of Oxides in Portland Cement
Oxide |
Common Name |
Content, % |
\[CaO\] |
Lime |
66-67 |
\[Si{{O}_{2}}\] |
Silica |
17-25 |
\[A{{l}_{2}}{{O}_{3}}\] |
Alumina |
3-8 |
\[F{{e}_{2}}{{O}_{3}}\] |
Iron |
0, 5-6 |
\[MgO\] |
Magnesia |
0, 1-4 |
\[N{{a}_{2}}O\,and\,{{K}_{2}}O\] |
Alkalies |
0, 2-1, 3 |
\[S{{O}_{3}}\] |
Sulphuric anhydride |
1-3 |
DIFFERENT FORMS OF CARBON ALLOTROPY
Allotropy
Carbon
Crystalline Forms of Carbon
Properties
(i) It is the hardest natural substance.
(ii) It is insoluble in any solvent.
(iii) It is of specific gravity 3.5.
(iv) It is non-conductor of heat and electricity.
(v) It bums in air at \[900{}^\circ C\] and gives out \[C{{O}_{2}}\].
(vi) It occurs as octahedral crystals.
(vii) It is transparent and has refractive index of 2.45.
(viii) It occurs in the free state.
Uses
(i) It is used in making jewellery.
(ii) It is used for cutting hand tools.
(iii) For drawing thin wires, diamond dies are used.
Properties
(i) It is soft.
(ii) Its specific gravity is 2.3.
(iii) It is good conductor of heat and electricity.
(iv) It is black in colour.
(v) It is insoluble in ordinary solvents.
(vi) It bums in air at \[700-800{}^\circ C\] and gives out \[C{{O}_{2}}.\]
(vii) It is of hexagonal crystals.
Uses
(i) It is used in writing pencils and lead.
(ii) It is used as a lubricant for high temperature.
(iii) It is used as refractory materials for designing crucibles and electrodes for high temperature.
(iv) It is used in electro-typing and manufacturing of gramophone records for making the non-conducting surface as conducting.
Amorphous Forms of Carbon
Uses
(i) It is used as a fuel.
(ii) It is used in the manufacturing of coal gas. The by-products of this process are coke, coal tar, ammonical liquor. Coal-tar is a source for making dyes, explosives, chemicals, etc.
(iii) It is also used in manufacturing fuel gases like producer gas. Water gas and semi-water gas.
(iv) It is used for manufacturing of synthetic petrol by catalytic hydrogenation of coal.
Uses
(i) It is used as fuel.
(ii) It is used for making graphite and water gas.
(iii) It is used as reducing agent in iron and steel industry.
Uses
(i) It is used as a fuel.
(ii) It is used a constituent of gun-powder.
(iii) It is used for purification of water.
(iv) It is used as deodorant and decolourising agent in sugar solution and gas masks.
Uses
(i) It is used in making India ink.
(ii) It is used in making printers ink.
(iii) It is also used by ladies for eyelids decoration.
Uses
(i) It is used in the rubber for making automobile tyres.
(ii) It is used as a replacement of lamp black used for many a purpose.
Use
(i) It is obtained when sugar is heated strongly out of contact with air.
(ii) It can be liquefied even to room temperature but under high pressure.
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