Chemical Compounds(educationpoint.co.cc)

STEPS … A T CY Pr ogr am _______________________________________________________________________________________ LECTURE NOTES – CHEMISTRY

SOME IMPORTANT CHEMICAL COMPOUNDS Washing Soda (Na2CO3. 10H2O) Washing Soda is actually Sodium Carbonate decahydrate, (Na2CO3. 10H2O). In which ten molecules of water of crystallization are present. Soda Ash (Na2CO3) – Anhydrous Sodium Carbonate is commonly known as Soda Ash. In India deposits of Soda are found in Dehradun, Mathura, Jaunpur, Varanasi in the form of reh or sajji. Sodium Carbonate is prepared on a large scale by Solvay Process (ammonia. soda. process) Raw materials used – NaCl, NH3, CaCO3 Sodium Chloride, ammonia & Calcium carbonate. SOLVAY PROCESS:

← NH3 + CO2 (TRACES)

CARBONATING TOWER

LIME KILN CaCO3

∆ ⎯⎯→ ⎯ CaO

+ CO2

BRINE

Calcium carbonated is heated to release Calcium oxide & CO2

NaCl + H2O + NH3

Ammoniacal brine Solution

NaCl + NH3 + H2O + CO2 NH4Cl + NaHCO3 Ammoniacal brine reacts with carbon dioxide to give ammonium chloride& Sodium hydrogen

CO2 ↓

CaO + H2O Ca(OH)2

SLAKED LIME

COOLING AMMONICAL BRINE

SATURATION TANK

AMMONIA RECOVERY TOWER Ca(OH)2 + NH4Cl STEAM

CaCl2 + 2NH3 + 2H2O

carbonate.

FILTER

NH4Cl + a little NH4CO3 FILTER

* concentrates “NaHCO3” & sends other chemical compounds to ammonia recovery tower 1 STEPS____________________________________________________________ Get free chapterwise tests for Class Xth on www.tcyonline.com

STEPS … A T C Y P r og r am _______________________________________________________________________________________ LECTURE NOTES – CHEMISTRY

Washing Soda: Washing Soda is a transparent, crystalline solid which is a major constituent of washing powder. Chemical formula of Washing Soda is Na2CO3. 10H2O Sodium Carbonate decahydrate. It is prepared by dissolving Sodium Carbonate crystals in water (limited). Na2CO3 + 10 H2O → Na2CO3. 10H2O Efflorescence: Some compounds which have water of crystallization when exposed to air loose them, this property of loosing water of crystallization is termed efflorescence. For instance when crystals of washing soda are left in open in air, they lose molecules of water of crystallization. Na2CO3. 10H2O → Na2CO3. H2O + 9H2O Uses of Sodium Carbonate: 1.

Manufacture of glass, soap, paper & other sodium compounds.

2.

Removing permanent hardness.

3.

Laundry as washing soda.

4.

Domestic purposes as cleaning agent.

5.

as a laboratory reagent.

Baking Soda: 1.

Baking Soda is Sodium hydrogen carbonate.

2.

Chemical formula: NaHCO3

3.

Commercially it is prepared from Solvay Process.

Properties: 1.

Crystals of Sodium Hydrogen Carbonate are white in colour.

2.

Sparingly soluble in water & solution is alkaline in nature.

Why Sodium Hydrogen carbonate is used in baking? If a solution of Sodium hydrogen carbonate is boiled or heated, carbon dioxide is given off. Hence it is used as a constituent of baking powder to aerate the dough. Heat 2NaHCO3 ⎯⎯ ⎯→ Na2CO3 + H2O + CO2

Sodium Hydrogen

Sodium Carbonate

Carbonate

2 STEPS____________________________________________________________ Get free chapterwise tests for Class Xth on www.tcyonline.com

STEPS … A T CY Pr ogr am _______________________________________________________________________________________ LECTURE NOTES – CHEMISTRY

Uses: 1.

used as an antacid.

2.

used as food additives in food (for baking) & drinks (effervescence)

3.

Used in fire extinguisher.

Bleaching Powder (CaOCl2):*

Chemical name: Calcium oxy chloride

Manufactured by the action of chlorine on dry slaked lime (Ca(OH)2) It is also called chloride of lime. Ca(OH)2 + Cl2 → CaOCl2 + H2O Bleaching Powder

Hasenclever plant for the manufacture of bleaching powder.

Properties: 1.

It is a yellowish white powder which smells of chlorine because it gradually loses its chlorine when left exposed to the air.

2.

CaOCl2 + CO2 → CaCO3 + Cl2 CaOCl2 + 2HCl → CaCl2 + H2O + Cl2 CaOCl2 + H2SO4 → CaSO4 + H2O + Cl2

Uses: 1.

Used for bleaching cotton, linen, paper, wood pulp.

2.

Used as oxidising agent in many chemical industries.

3.

Used for disinfecting drinking water to make it free from germs.

STEPS____________________________________________________________ 3 Get free chapterwise tests for Class Xth on www.tcyonline.com

STEPS … A T C Y P r og r am _______________________________________________________________________________________ LECTURE NOTES – CHEMISTRY

1 ⎛ ⎞ Plaster of Paris: ⎜ CaSO 4 . H 2 O ⎟ 2 ⎝ ⎠ Chemical composition – CaSO4.

1 H2O 2

Preparation:

POP is obtained by heating gypsum (CaSO4. 2H2O) at 373K.

1 1 373 ⎯→ CaSO 4 . H 2 O +1 H 2 O CaSO4 . 2H 2 O ⎯⎯ 2 2 Gypsum Plaster of Paris Properties of POP:

1.

White powder, when dissolved in water, crystals of gypsum are produced again & set to form a hard solid mass. 1 CaSO4 . H 2 O → CaSO4 . 2H 2 O 2 Gypsum

Uses: POP is used in making

1.

toys, decorative material, jewellery, cosmetics & cases for statues.

2.

For setting fractured bones in right position & dentistry.

3.

Smooth surfaces & ornate design on walls & ceiling.

4.

In laboratories for sealing the air gaps in apparatus to make it air tight.

Lime (CaO):

1.

This is a man – made chemical, it is made by heating lime stone (CaCO3).

Manufacture:

A vertical lime kiln.

4 STEPS____________________________________________________________ Get free chapterwise tests for Class Xth on www.tcyonline.com

STEPS … A T CY Pr ogr am _______________________________________________________________________________________ LECTURE NOTES – CHEMISTRY

Lime is made by heating lime stone at about 1273K in a lime kiln & the process is called calcining. 1237K CaCO3

⇌

CaO + CO 2

Lime Stone

Lime

Properties:

1.

Calcium oxide is an amorphous white solid having a high melting point (2273K).

2.

When added to water, produces hissing sound & generates heat & form slaked lime (calcium hydroxide).

Calcium oxide does not react with dry hydrogen chloride gas, but it reacts with moist hydrogen chloride gas to form calcium chloride. Uses:

1.

Lime is used as a drying agent in the lab for drying ammonia & alcohol.

2.

Used for manufacture of calcium chloride, cement & glass.

3.

Used in making lining of furnaces.

4.

Used for white washing.

Cement:

It is one of the most important building materials used throughout the world. It is a fine grey powder which sets after a few hours when mixed with water & then hardens in a few days into a solid & strong material. Manufacture

Raw material: Limestone & clay Lime → CaO → 60 – 70% ⎧SiO 2 → 20 − 25% ⎪ Clay ⎨Al 2 O 3 → 5 −10% ⎪Fe O → 2 − 3% ⎩ 2 3 Sand & Clay are taken in ratio 3: 1 by mass. The mixture is ground to a fine powder. Finely ground powder is then heated to 1773 K in a rotary kiln to produce clinker. Clinker – It is the homogenous mixture which is produced in rotary kiln & made up of

dicalcium silicates (Ca2SiO4) Tricalcium Silicate (Ca3SiO5) & tricalcium aluminate (Ca3Al2O6). The clinker is cooled & mixed with 2 – 5% gypsum, to delay its setting time. Diagram Uses:

1.

Cement is mixed with sand to form mortar, which is used for plastering and binding bricks and stones.

2.

A mixture of cement with sand and aggregates of crushed stones is called concrete, which is used in the construction of buildings, roads, dams, bridges, etc.

STEPS____________________________________________________________ 5 Get free chapterwise tests for Class Xth on www.tcyonline.com

STEPS … A T C Y P r og r am _______________________________________________________________________________________ LECTURE NOTES – CHEMISTRY

3.

Steel rods, bars and other hard materials are sometimes embedded in the wet concrete. As the concrete sets, it sticks to these materials to form reinforced concrete cement (RCC), which is much stronger. Other materials used for

reinforcing concrete are asbestos, wire – mesh, bamboo, etc. RCC is used for making pipes, gutters, etc. Glass:

Manufacture: Average composition of ordinary glass (Soda glass) corresponds to the formula. Na2O. CaO. 6SiO2. A mixture of Sodium Carbonate & Sand is finely powdered. The mixture is known as batch is mixed with broken glass pieces called cullet & then fused in a tank furnace at 1673. *

Cullet increases the fusibility of the glass produced. Na 2 CO 3 + SiO 2 → Na 2 SiO 3 + CO 2 Sodium Carbonate

Sodium Silicate

CaCO3 + SiO 2 → CaSiO3 + CO 2 Calcium

Calcium

carbonate

Slicate

Figure Annealing of glass:

The hot molten glass is cooled slowly & uniformly & the process is called annealing. *

Annealed glass is of good quality.

Different kinds of glasses & their uses:1)

Soda glass:- Soft glass

–

cheapest & most common form of glass.

–

Prepared by fusing soda ash, sand & lime stone.

–

Fuses at comparatively low temperature.

Disadvantage – It is brittle & breaks easily.

– Sensitive to temperature. – Sensitive to chemicals. Uses:

Used for manufacturing of window glass, mirror, common glassware. 2)

Hard glass: K2CO3 + CaCO3 (Prepared by fusing pot. Carbonate & calcium

carbonate)

6 STEPS____________________________________________________________ Get free chapterwise tests for Class Xth on www.tcyonline.com

STEPS … A T CY Pr ogr am _______________________________________________________________________________________ LECTURE NOTES – CHEMISTRY

Uses:

Making hard glass apparatus. Advantage:

More resistant to the action of acids. 3)

Lead crystal glass: Made from potassium carbonate, lead oxide & sand. Advantage: This glass has high refractive index. Uses: Used for making expensive glassware.

4)

Pyrex glass: Borosilicate glass. Made from sand, lime & borax & alkali carbonate. Advantage: Good chemical durability & thermal shock resistance. Uses:

– Making laboratory apparatus. – pharmaceutical containers – oven - ware

5)

Optical glass: Advantages: Free from stains & defects. Uses:

Making lenses for spectacles, microscopes, cameras & telescope & other

instruments. 6)

Photochromatic glass:

– Temporarily darkens when exposed to bright light.

Advantage:

– Temporarily darkens when exposed to bright light.

Uses:

– Useful as Sunshield. – Used in window glasses, spectacles, glasses etc.

7)

Safety glass: Manufacturing:- Prepared by placing a layer of transparent plastic between the two

layers of glass by means of a suitable adhesive. The three layers are used by the action of heat to pressure. Uses: Used in making wind screens of aeroplanes, automobiles, bullet proof glass.

8)

Glass fibres:

This is the glass in the form of fibres. Advantage: This is an excellent heat insulator used for insulating materials in

refrigerators, oven etc. * Optical fibres:- extensively used in telecommunication surgical operation etc. * Used in endoscopy to examine the internal human organs. 9)

Coloured glass: Manufacture: by adding certain colouring material, such as metallic oxides, to the

molten mass. Difference addition may produce different coloured glass. * Ferric oxide → brown colour.

STEPS____________________________________________________________ 7 Get free chapterwise tests for Class Xth on www.tcyonline.com

STEPS … A T C Y P r og r am _______________________________________________________________________________________ LECTURE NOTES – CHEMISTRY

* Chromic oxide → green colour. * Manganese dioxide → purple colour. * Cobalt oxide → blue colour Uses: Manufacturing of fancy articles, window panes, artificial gems. STEEL:

1.

An alloy of iron & carbon. Other elements added are: Manganese, molybdenum, lungsten & several other elements. Steel industry began in 1870 in Indra, when the Bengal Iron works company set up its plant at Kulti in West Bengal.

2.

The carbon content of steel is intermediate b/w that of pig iron (cast iron) & wrought iron. It contains 0.10 – 1.5% carbon. Figure

3.

Steel is manufactured from pig iron in a Bossemer converter, which is a pear shaped furnace lined with silica or lime. Molten pig iron is introduced into the converter & a blast of hot air is passed in & the following reaction takes place. 2Mn + O2 → 2MnO Impurity Si + O2 → SiO2 Impurity 2C + O2 → 2CO MnO + SiO2 → MnSiO3 (Slag) 4P + 5O2 → 2P2O5 3CaO + P2O5 → Ca3(PO4)2 (Slag) When all the carbon is completely removed, the requisite amount of carbon is added to convert iron into different varieties of steel.

Properties:

The properties of steel depend upon the amount of carbon content . Mild steel contains 0.1 to 0.4 % of carbon. Hard steel contains 0.5 to 1.5 % of carbon. Quenching: Hard steel can be further hardened by heating it to red hot (1123 K) & then

cooling it by plunging it into the cold water. This steel is called quenched steel.

8 STEPS____________________________________________________________ Get free chapterwise tests for Class Xth on www.tcyonline.com

STEPS … A T CY Pr ogr am _______________________________________________________________________________________ LECTURE NOTES – CHEMISTRY

Tempering: If the quenched steel is reheated & allowed to cool slowly it becomes elastic &

much less brittle. * Steel of any desired degree of hardness can be produced by adjusting the temperature of tempering. Annealing: If steel is heated to bright red heat & is then cooled slowly, the process is

called annealing. * Annealed Steel is Soft. TYPES OF STEEL:

1.

STEEL containing MANGANESE:-

Steel containing 7 – 20% manganese is very hard & tought. Uses: Used for making steel – helmets, rock crushing machinery etc.

2.

CHROMIUM AND NICKEL STEEL: Uses:

(a) Making aeroplane parts, motorcars, bicycle parts etc. (b) Scientific instruments are made if the percentage of nickel is 36. (c) Lamp bulbs & radio values are made if the percentage is 46.

3.

COBALT STEEL: contains upto 35% cobalt.

* Possesses exceptional magnetism. Uses: Making permanent magnets.

4.

SILICA STEEL: Upto 35% Silicon & a very little carbon is present. Uses: Making transformers & electromagnets.

Silica Steel (15% Silicon) is acid resistant. Uses: Making pumps & pipes which carry acids.

5.

STEEL having 15 – 20% TUNGSTEN & a little vanadium, 5% chromium. Uses: Making drilling tools.

6.

STAINLESS STEEL: 18% chromium & Nickel is resistant to corrosion & is therefore

used for making utensils & surgical instruments.

STEPS____________________________________________________________ 9 Get free chapterwise tests for Class Xth on www.tcyonline.com