2. 1. Ethanol:
Harmful:
Pure Ethanol will irritate the skin and eyes. Nausea, vomiting and intoxication
are symptoms of ingestion. Long term use by ingestion can result in serious liver
damage. Death from Ethyl alcohol consumption is possible when blood alcohol
level reaches 0.4%.
A blood level of 0.5% or more is commonly fatal. Levels of even less than 0.1%
can cause intoxication, with unconsciousness often occurring at 0.3–0.4%
Highly flammable:
It has a flash point of 13 o
C. It can readily catch fire. So care should be taken
while handling it because its combustion products include Acetaldehyde which
is a strongly carcinogenic substance. However, ethanol itself is not cancer
causing.
Properties of Ethanol:
IUPAC Name Ethanol
Other names
Absolute alcohol
Drinking alcohol
Ethyl alcohol
Ethyl hydrate
Grain alcohol
Hydroxy-Ethane
Appearance Colorless liquid
3. Structure
Molecular formula C2H6O
Molar mass 46.07 g mol-1
Density 0.789 g cm-3
Melting point -114.3 o
C
Boiling point 78.4 o
C
Solubility in water Miscible
Acidity (Pka) 15.9
Flash point 13 o
C
Auto-ignition temperature 422 o
C
Sodium Di-chromate:
Oxidant:
Sodium di-chromate is a strong oxidizing agent. It will readily oxidize
anything that will come into contact with it. Precautionary measures are
necessary while handling it.
Corrosive:
It is a strongly corrosive compound as it readily oxidizes anything.
Dangerous to Environment:
It is a Hexa-valent chromium ion so is considered hazardous. It can
contaminate potable water as it is of carcinogenic properties.
4. Very toxic:
If swallowed, this compound can even cause death because it is very toxic
compound. It is carcinogenic in nature. Potable water should especially be
treated which may contain Hexa-valent chromium compounds.
Harmful:
It is a very harmful substance. Its contact with skin should be avoided.
Properties of sodium di-chromate:
IUPAC name Sodium dichromate
Other names Chromic acid, (H2Cr2O7), disodium salt
Structure
Molecular formula Na2Cr2O7
Molar mass
261.97 gmol-1
(anhydrous)
298.00 gmol-1
(di-hydrate)
Appearance
Density 2.52 g cm-3
Melting point 356.7 o
C
Boiling point 400 o
C decomposes
Solubility in water 730 g/ l (25 o
C)
5. Sulphuric acid:
Corrosive:
It is a strongly corrosive compound as it readily oxidizes anything.
Dangerous to Environment:
Although sulfuric acid is non-flammable, contact with metals in the event of a
spillage can lead to the liberation of hydrogen gas. The dispersal of acid aerosols
and gaseous sulfur dioxide is an additional hazard of fires involving sulfuric acid.
Very toxic:
Sulfuric acid is not considered toxic besides its obvious corrosive hazard, and the
main occupational risks are skin contact leading to burns and the inhalation of
aerosols. Exposure to aerosols at high concentrations leads to immediate and
severe irritation of the eyes, respiratory tract and mucous membranes.
Properties of sulfuric acid:
IUPAC name Sulfuric acid
Other names Oil of vitriol
Structure
Molecular formula H2SO4
6. Molar mass 98.06 g/gmol
Appearance
Density 1.84 g/cm3
(liquid)
Melting point 10 o
C
Boiling point 337 o
C
Solubility in water Miscible
Acidity (Pka) -3
Viscosity 26.7 cP (20 o
C)
Flash point Non- flammable
Water:
It is a non-hazardous compound.
Environmentally safe:
Water is an essential part of life. Life cannot be sustained without water.
Food & eatables contain some amount of water in them. It is a non-
hazardous compound.
IUPAC name
Water
Oxidane
Other names
Hydrogen oxide
Dihydrogen monoxide
Hydrogen monoxide
Hydroxylic acid
Hydrogen hydroxide
R-718
Oxygen dihydride
7. Oxygen hydride
Oxane
Structure
Molecular formula H2O
Molar mass 18.0152833 gmol-1
Appearance
Density
1000 kg m-3
(liquid)
917 kg m-3
(solid)
Melting point 0 o
C
Boiling point 99.98 o
C
Acidity (Pka) 15.74
Basicity (Pkb) 15.74
Viscosity 0.001 Pa.S (20 o
C)
8. Preparation of Acetic Acid
Chemicals required:
1) Ethanol 2) Sodium di-chromate
3) Concentrated H2SO4 4) Water
Apparatus Required:
Bolt head flask Dropping funnel
Knee tube Water condenser
Adopter Conical flask beaker
Stirrer
Chemical Equation:
CH3CH2OH
[O]
CH3CH (OH) 3
[-H
2
O]
CH3CHO
[O]
CH3COOH
Procedure:
1) Place 15 ml of water into the Bolt head flask. Add 10 ml of concentrated H2SO4slowly with
shaking. Finally add 10.5 g of Na-Dichromate & some fragments of porcelain.
2) Place a mixture of 4.5 ml of ethanol & 18ml of water in dropping funnel.
3) Fit a bolt head flask with reflux H2O condenser to the top of which a dropping funnel is fixed.
4) Add Ethanol-H2O mixture drop by drop down the condenser into the flask. A vigorous reaction
occurs & mixture becomes green.
5) When the addition is complete & reaction is subsided, heat the flask on a boiling H2O bath for 15-
20 minutes.
6) Detach & reverse the condenser & re-connect it to the flask through a knee tube for direct
distillation & distill the mixture by direct heating.
Uses of Acetic acid:
Acetic acid is used:
As a coagulant for latex in rubber industry
In the manufacture of plastics (polyvinyl acetate) rayon (cellulose acetate) and silk
In medicine as a local irritant
9. As a solvent in laboratory for carrying out reactions
In the manufacture of pickles
In the manufacture of many organic compounds like acetone, acetates and esters
Industrial preparation of acetic acid:
Feed tank:
Weak acetaldehyde is fed into this tank. Cooling brine is used to remove heat of acetaldehyde.
Heat exchanger:
From storage CH3CHO is fed to next unit via a heat exchanger where the feed stream is heated by
exchange of heat with steam coming out of acetaldehyde still.
Acetaldehyde still:
In this unit the acetaldehyde is heated to remove any water contents or other volatile materials. Pure
acetaldehyde is cooled with cooling brine in coils and is sent to the pure acetaldehyde storage tank.
Oxidizing kettle:
This is the reaction zone. Here air at a pressure of 70 Psi is introduced and catalyst is added.
Acetaldehyde is converted into acetic acid.
Off gases like nitrogen are collected at the top and sent to a scrubber where it is washed with water and
vented to atmosphere and un-reacted material is sent back via recycle stream again into the process.
Acetic acid still:
Crude acetic acid is again refined via a still and stored in a refined acetic acid tank.
References:
1. Shreve’s chemical process industries by George T. Austin
2nd
edition, page 947-948
2. Unit processes in organic synthesis by P.H. Groggins
5th
edition, page 509-510
3. Wikipedia
http://en.wikipedia.org/wiki/acetic_acid/
