Chemistry Experiments: June 2010

Monday, June 28, 2010

Piperonal

Piperonal is also known as 3,6-methylene-dioxy-benzaldehyde OR heliotropine.

Source of piperonal :The main source of piperonal is the fruits of vanilla species. In small quantities it is seen in some flower oils.
Uses of piperonal : Piperonal is used in perfumery, cosmetics & soaps.

Friday, June 18, 2010

Fehling's solution

Copper sulphate + sodium potassium tartarate(Rochelle salt) + NaOH

Lindlar Catalyst

Palladised charcoal deactivated with sulphur compounds...

Thursday, June 17, 2010

Preparation Of Catalyst Mixture

AIM:
To prepare catalyst mixture used for the determination of Nitrogen in raw natural rubber.
PRINCIPLE:
Catalyst mixture consists of Potassium sulphate, Copper sulphate & Selenium powder in the ratio 15:2:1
REAGENTS:

K₂SO₄ :15 gm
CuSO₄ : 2 gm
Selenium powder : 1 gm

APPARATUS:

Grinder
Spatula
Paper
Stoppered bottle

PROCEDURE:

Weigh 15 gm K₂SO₄ & 2 gm CuSO₄.
Powder the above mixture in a grinder.
Transfer the above powder to a neat paper.
Add 1 gm selenium powder to the above mixture & mix thoroughly well using a spatula.
Place the catalyst mixture in a stoppered bottle.

Wednesday, June 16, 2010

Determination Of Nitrogen Content Of Rubber

AIM:
To determine the nitrogen in raw natural rubber using Kjeldahl semi micro method.
CHEMISTRY:
This is done to find the protein content in raw natural rubber. If protein content is greater, nitrogen is greater & if protein content is lesser, nitrogen is lesser.
PRINCIPLE:
A known mass of the sample is digested with a mixture of H₂SO₄, catalytic amounts of CuSO₄ & Se.The end product is distilled after making it alkaline. The distilled product is absorbed in H₃BO₃, followed by titration with standard acid.
REQUIREMENTS:

Kjeldahl distillation unit
Balance
Nitrogen Tube
Semi micro burette
Measuring cylinder 10ml
Conical flasks 100ml

REAGENTS:

67% NaOH solution
Methyl orange indicator
Phenolphthalein indicator
0.1N Na₂CO₃ solution
0.1N NaOH solution
Boric acid solution
Catalyst mixture ( 15:2:1)
0.01N H₂SO₄

PROCEDURE:

Weigh accurately about 0.1gm of the blended rubber into the Nitrogen tube.
Note the weight taken.
Add 3ml con H₂SO₄ & 0.65 gm of catalyst mixture into the nitrogen tube.
Boil gently until the contents become clear green in colour with no yellow tint.

CARE SHOULD BE TAKEN WHILE DOING THIS EXPERIMENT..ALSO THE ABOVE TEST SHOULD BE DONE IN A SEPARATE ROOM PROVIDED IN THE LAB..NO PERSON SHOULD STAND NEAR TO IT..THE VAPOURS FROM IT ARE DANGEROUS TO HEALTH.

Cool & transfer the contents with small portion of distilled water, to the distillation apparatus, which has been previously steamed out for 30 minutes.
Add 10ml 67% NaOH solution to the flask.
Take 10ml H₃BO₃ solution in the 100ml flask.
Place the flask in the receiver.
Pass steam through the apparatus till 50- 75ml distillate is collected in the receiver.
Colour of H₃BO₃ changes from violet to green.
Remove the flask , titrate with 0.01N H₂SO₄ till the colour changes from green to violet.
Note the burette reading.

RESULT:

From the weight of the sample, normality of H₂SO₄ & the burette reading for sample, the % of nitrogen in rubber can be calculated...

Name the minor elements needed for plant growth?

Fe, Mn, Cu, Mo, Sn & Cl₂

Which are the major elements needed for plant growth?

N,P,K,Ca & Mg

What are called stimulant fertilisers?

Sometimes it is necessary to add certain chemicals which are not plant nutrients themselves. But they help the nutrients already present in the soil to be more readily available to plants. These are called stimulant fertilisers.

Tuesday, June 15, 2010

Give examples of stimulant fertilisers

Lime
Gypsum

Mention the most widely used compounds of Potassium

Potassium nitrate

Name the most important phosphatic manure

Calcium superphosphate

What are the common nitrogeneous fertilisers?

Ammonium sulphate
Ammonium nitrate
Urea
Nitrates of potassium & Calcium

What are the essential requirements of a good fertiliser?

Soluble in water
N, P or K contained in it should be in such a form that it can readily be made available to plants.

What are artificial manures?

Artificial manures or fertilisers are chemical compounds containing N,P,K..

Give egs of natural manures

Animal dung, Blood, Bones, Fish scrap, Animal excreta etc..

What are the types of manures?

Natural
Artificial ( Chemical fertilisers)

What do you mean by NPK Fertilisers?

Potassium compounds are generally used in mixed fertilisers containing Nitrogen & Phosphorous. Such materials are commonly referred to as NPK fertilisers.