C, Si And Its Compounds

Question 1

Uses of graphite
Uses of charcoal
Uses of carbon black
Uses of coke

Answer 1

Graphite fibres- lightweight composite- tennis racket, fishing rods, aircraft and canoes.
Good conductor- electrodes in battery, industrial electrolysis
Crucibles- inert to dil acids and alkalies

Adsorbs poisonous gas, used as a filter in water, in ac to control odour.

Black pigment

Fuel and reducing agent in metallurgy

Question 2

Carbon monoxide
Prep
Prep in small scale
Prep on commercial scale
When C + air instead of steam

Answer 2

Direct oxidation of C in limited supply of oxygen
Small scale - dehydration of formic acid
Steam over hot coke - gives CO+H2 (water gas)
CO + N2 (producer gas)

Question 3

Carbon monoxide
Colour, odour
Solubility
RA

Answer 3

Colourless, odourless
Almost water insoluble
Reduces all metal oxides except those of alkalies and alkaline earth metals, aluminium and a few transition metals - hence used in extraction of metals from their oxide ores.

Question 4

Carbon dioxide
Prep
Prep in Lab
Prep on commercial scale
Colour, odour
Why is it of great bio chemical and geo chemical importance.

Answer 4

Complete combustion of carbon and carbon containing fuels in excess air.
CaCO3 + Dil HCl
Heating limestone
Colourless, odourless
Low solubility in water

Question 5

Co2 + H2o
Dibasic / monobasic?
Buffer system

Answer 5

Carbonic acid
Dibasic
Helps to maintain the ph of blood between 7.26 to 7.42

Question 6

Silicon dioxide
Percentage composition
Crystalline forms of silicon
2D / 3D?
How many membered ring
Reactivity
Attacked only by

Answer 6

95%
Quartz, cristobalite and tridymite - interconvertable at suitable temp
3D
8
Non reactive - high bond enthalpy
HF and NaOH

Question 7

Silicones

Repeating units
Starting material
Straight chain polymers
What blocks the ends?
Why is it water repelling?
Features
Uses
Use as biocompatible feature

Answer 7

R2SiO
Alkyl or aryl substituted silicon chloride
Hydrolysis of (ch3) 2 SiCl2
(Ch3)3SiCl blocks the ends
Surrounded by non polar alkyl groups
High thermal stability, high dielectric strength, resistance to oxidation and chemicals.
Sealant, greases, insulators, water proofing fabrics.
Surgical and cosmetic plants

Question 8

Silicates
Example
Man made silictaes

Answer 8

Feldspar, zeolite, mica and asbestos
Glass and cement

Question 9

Zeolite (alumino silicate)
Prep
Use

Answer 9

Al replaces a few si atoms in sio2
Catalyst in petroleum industry - cracking hydrocatbons
Converts alcohol directly into gasoline
Softening hard water