Name the residue tests for latex

• Sludge content
• Coagulum content

What is the importance of sludge?

It refers to non polymer impurities which tend to sediment under the influence of gravity.

What is the expression for sludge content?

% of the initial sample weight.

Give the expression for coagulum content

% of the weight of latex sample.

What are the contents of coagulum?

Polymer coagulum,foriegn matter

What do you mean by coagulum?

'Material which is retained by a mesh of arbitrary size under specified conditions of test'

Which form of copper is estimated using photoelectric absorptiometer?

Copper diethyl dithiocarbamate

What is the purpose of adding citric acid in determining Copper?

To complex any iron

What is the temperature of muffle furnace used in the determination of ash content of rubber?

550 degree celsius

Important Notes On Alkalinity

• High Ammonia :Alkalinity 1.6%
• Medium Ammonia : Alkalinity above 0.8% but less than 1.6%
• Low Ammonia : Alkalinity of not more than 0.8%

What is the inferior property of skim rubber?

Tendency to scorch

Give the TSC of Cenex

61.5

Give the DRC of cenex

60

What do you mean by non rubber solid?

It is the difference between TSC & DRC

What are the uses of latex?

Rubber thread, Foam, Carpets, Adhesives

Egs of preserved latex

Field latex or Concentrated latex

What is meant by spontaneous coagulation?

The presence of non rubber constituents like proteins, carbohydrates etc in latex makes it a suitable medium for the growth of micro organisms. Because of the proliferation of microorganisms, organic acids are produced & this decrease the stability of latex & eventually coagulates it.This is called spontaneous coagulation( 6- 12 hours).

What is latex?

It is a negatively charged colloidal dispersion of rubber particles in an aqueous serum.

Name the important methods in chemical separation of effluent treatment

Precipitation, Flocculation, ion exchange, oxidation & reduction reaction

Important methods in physical separation of effluent treatment

Filtration,sedimentation & reverse osmosis

Name the 3 basic methods of effluent treatment

Physical, chemical & biological

Name the 2 potential pollutants in the effluent

Organic carbon & ammoniacal nitrogen

Name the important characteristic of rubber effluent

Significant level of nitrogen, mainly in the ammoniacal form

Question

In effluent the high content of total solid, mainly dissolved organic solids, is resposible for what?
High oxygen demand

Question

Name the factor which is responsible for the variation in pH of effluent from different types of factories: Quantity of acid used.

Question

Which are the factors of effluent which tend to deplete the dissolved oxygen in water & endanger aquatic life?
High BOD & COD

Name the type of bacteria found in rubber effluent

Coliform, streptococci & E.coli

Define COD

COD measures the quantity of oxygen required for chemical oxidation of organic matter in the sample to carbon dioxide & water.

Define BOD

BOD measures the quantity of oxygen utilised by a mixed population of micro organisms in the aerobic oxygen.

What are the constituents of an effluent?

Rubber particles,Proteins, sugar, lipids,carotenoids, inorganic & organic salts.

What is an effluent?

The large quantity of water used for washing,cleaning & dilution of latex, the serum obtained after coagulation & the water used for washing & cleaning during processing constitute the effluent.

Determination of pH of a fertiliser

AIM:
To determine the pH of a given fertiliser.
REQUIREMENTS:

• Fertiliser sample
• Electronic balance
• 250ml beaker
• Glass rod
• Distilled water
• pH meter
• Buffer solution of pH 7

PROCEDURE:

• Weigh 5gm of the given fertiliser sample.
• Note the weight taken.
• Put the weighed sample into a 250ml beaker.
• Add 100ml distilled water.
• Stirr using glass rod.
• Adjust the value of pH meter using buffer solution of pH 7.
• Place the fertiliser sample & note the pH corresponding to it.
• Report the pH value corresponding to 5 gm of sample.

The working of a pH meter is already explained in the previous experiment.

Determinaton of pH of water

AIM :
To determine the pH of water.

REQUIREMENTS :

• pH meter
• Water sample
• 250ml beaker
• buffer of pH 7

PROCEDURE:

Working of a pH meter :

The pH meter is set up first with distilled water for atleast 30 minutes.Then clean the rod with filter paper.Place pH 7 solution & adjust the pH to 7.Clean the rod again with filter paper.Place the water sample & note the pH either at 0-7 or 7-14.
Step 1:
Shake the sample bottle well.
Step 2:
Transfer 150ml water sample in a 250ml beaker.
Step 3:
The pH meter is set to 7 with buffer solution of pH 7.
Step 4:
Then place the water sample .Adjust either 0-7 or 7-14 & note the pH of the solution.

How will you determine the pH of a solution using pH paper?

The pH paper is dipped in the given sample of the solution. The colour developed on the paper is compared with standard colour chart & the pH of the solution is predicted.

What do you mean by pH paper?

pH paper is a strip of paper prepared by dipping it in the solutions of different indicators & then drying it.It can be used to determine the approximate pH of any solution.

What is an acid-base indicator?

It is an organic compound which gives one colour in acid medium & another colour in basic medium.

The pH of a solution is 7.1.How does this solution react towards red litmus?

The solution is basic. Hence red litmus will be turned to blue.

What change is observed when a red litmus paper is dipped in lemon juice?

Lemon juice is acidic. Hence no change is observed.

How is the pH of water changes when a drop of concentrated sulphuric acid is added?

pH of water decreases.

How will you say whether a given solution is acidic or basic on the basis of pH?

pH greater than 7 is basic & pH less than 7 is acidic.

What is pH?

It is the negative logarithm of hydronium ion concentration in moles per litre.

What is the value of pH of a neutral solution?

7

What is the value of pH for water?

7

Preparation of 0.1N or N/10 sodium carbonate solution in 250ml standard flask

Weight of sodium carbonate required to prepare 250ml 0.1N solution =1.325 gm

Why should a burette & pipette be rinsed always?

Otherwise the water drops sticking inside the burette & pipette will change the concentration of the respective solution. This will introduce error in the experiment.

Weight blocks should not be handled with fingers.why?

Dirt or moisture on fingers may stick to the weight blocks & introduce error in weighing.

What is the use of a pipette?

To transfer a definite volume of a solution ( eg: 20ml) accurately.

What is the use of a burette?

To transfer any volume of a solution accurately .eg: 21.6ml

A pipette should not be held by the bulb. why?

The body temperature is more than the normal atmospheric temperature & hence the bulb may expand a little & cause in the volume transferred.

What do you mean by basicity? give egs

Basicity means number of replaceable H atoms.
For eg: In the case of HCl, the basicity is 1

Equivalent mass of an acid

Equivalent mass of an acid =Molecular mass of acid/basicity of acid

Acidimetry & Alkalimetry

Acidimetry is the estimation of alkali solution using standard acid solution.
Alkalimetry is the estimation of an acid solution using standard alkali solution.

Iodimetry & Iodometry

Estimations using standard iodine solution are called iodimetry & those involving iodine liberated from potassium iodide solution by a chemical reaction is iodometry.

What is a primary standard?

• It is a chemical substance whose standard solution can be prepared by direct weighing & dissolving it in water.

What is meant by equivalent mass of a reducing agent?

• It is the molecular mass divided by number of electrons lost by one molecule of the reducing agent.

What is meant by equivalent mass of an oxidising agent?

• It is equal to the molecular mass divided by number of electrons gained by one molecule of the oxidising agent.

What is the weight of a rider?

10 mg

What is meant by an end point?

• It is the point in a titration at which the reaction between the two solutions is just complete.

What is the basis of bromine water test?

• Unsaturated compounds form colourless addition products with bromine.

How is phenolic -OH & alcoholic -OH identified?

• Phenolic -OH by neutral ferric chloride
• Alcoholic -OH by metallic sodium.

What is a functional group?

• The group of atoms in an organic compound that determines the properties of that compound is called a functional group.

What type of compounds give liebermann's nitroso reaction?

• Compounds containing phenolic-OH group.

What is tollen's reagent?

• Ammoniacal silver nitrate solution

What is meant by a standard solution?

• A solution of known concentration is called a standard solution.

What is a molar solution?

• A molar solution is one which contains one mole per litre of the solution.

What is a normal solution?

• A solution containing one gram equivalent of a solute is called normal solution.

What is meant by the term molarity?

• It is the number of gm moles of solute per litre of the solution.

Define the term normality

• It is the number of gm equivalents of solute per litre of the solution.

General Questions In Chemistry

• First Nobel Prize in chemistry : Vant Hoff
• Highest electron affinity : chlorine
• Highest electronegativity : Fluorine
• Artificial explosive : Dynamite
• Most reactive solid element : Li
• Most abundant metal of earth : Al
• Most abundant element of earth : Oxygen
• Rarest element of earth : Astatine
• Best electrical conductor among metals : Ag
• Best conductor among non metals : graphite

Give the chemical name for paracetamol

N-acetyl-p-aminophenol or Acetaminophen

Question

• Name the process of separating a solid from a liquid by pouring off the liquid into another container : Decantation

Give the full name of D.D.T

Dichloro diphenyl trichloro ethane

Give the approximate normality of hydrochloric acid

11.3

Formic Acid Purity

AIM:

To determine the purity of given sample of formic acid.

APPARATUS:

• 50ml erlenmeyer flask
• Electronic balance
• 500ml beaker
• Burette
  

REQUIREMENTS:

• Formic acid sample
• Distilled water
• Phenolphthalein indicator
• 1N NaOH solution
  

PROCEDURE:

• Shake the given sample of formic acid.
• Transfer 20 ml to an erlenmeyer flask provided with a stopper.

• Transfer 1-2 gm of the sample to 300ml distilled water taken in a 500ml beaker containing 2 or 3 drops of phenolphthalein indicator.



• Note the weight taken.



• Titrate the contents in the beaker against 1N NaOH solution from the burette.

CALCULATION PART:
From the weight of sample taken, volume of NaOH & normality of NaOH , the purity of formic acid can be calculated.

Lauric Acid Purity

AIM:

To determine the purity of given sample of lauric acid.

APPARATUS:

• Electronic balance
• 500ml conical flask : 2
• Water bath
• Dropper
• Burette
  

REQUIREMENTS:

• lauric acid sample
• Ethanol
• Phenolphthalein
• 0.1 N NaOH

PROCEDURE:

• Weigh 1gm of lauric acid sample using an electronic balance.
• Note the weight taken.
• Add the weighed lauric acid sample to a 500ml conical flask.
• Add 50ml ethanol to the conical flask.
• Heat the conical flask on a water bath till the contents dissolve.
• Cool for a while.
• Add 1 drop of phenolphthalein to the conical flask .
• Titrate against 0.1 N NaOH from the burette.
• A blank is also conducted.
  

CALCULATION:

From the weight of lauric acid taken, volume of NaOH & normality of NaOH, the purity of lauric acid can be calculated.

General chemistry questions- Part 2

• What is the chemical name for brimstone : sulphur
• Give the chemical name for quick silver: mercury
• What is grape sugar : dextrose
• Name the fruit sugar : fructose
• Write the chemical name for cinnabar :Mercuric Sulphide
• Write the chemical name for nitre : Potassium nitrate
• What is the chemical name for chile saltpetre : Sodium nitrate

General chemistry questions- Part 1

• Give the common name for nitric acid :Aqua fortis
• Give the chemical name for Muriatic acid : Hydrochloric acid
• Give the chemical name for oil of vitriol : Sulphuric acid
• Give the chemical name for vinegar : Dilute acetic acid
• Give the chemical name for aqua regia: Mixture of con nitric acid & con hydrochloric acid in the ratio 1:3

Interesting chemistry questions

• Name the pure acid of vinegar : Acetic acid
• Which is the smallest part of an element capable of taking part in a chemical reaction : Atom
• Common name for substances having both acidic & basic properties : Amphoteric
• Give an eg. for amphoteric substances : alumina
• Another name for methyl alcohol : Wood alcohol
• Common form of alum: Potash alum
• Name an inert chemical element used in light bulbs: Argon