Question 1

What is Rf value? Why it has no units?(

Accepted Answer

The Rf value is defined as the ratio of the distance moved by the solute (i.e. the dye or pigment under test) and the distance moved by the the solvent (known as the Solvent front) along the paper, its a ratio so it has no units

Question 2

Define distribution law and how is it helpful in solvent extraction?

Accepted Answer

freetext://Solute distributes itself between two immiscible liquids. Solvent extraction follows distribution law which states
 “ a solute distributes itself between two immiscible liquids irrespective of amount of solute added”. Thermally unstable or volatile components are separated.

Question 3

Give the salient features of the ideal solvent used in the process of crystallization?(

Accepted Answer

Should Dissolve maximum amount at high temperature and minimum amount at low temperature
Unreactive
Should not dissolve impurities
Should help form crystals
Inexpensive
Safe to use 
Can be mixture of solvents

Question 4

Define chromatography. Give its two uses.

Accepted Answer

It is technique in which mixture of colors/solute is separated on the basis distribution in two solvents

Question 5

During the crystallization, the hot saturated solution is

Accepted Answer

cool at a moderate rate to get medium size crystals

Answer

is evaporated to get the crystals of product

Answer

Cold very slowly to get large size crystals

Answer

Is mixed with immiscible liquid to get the crystals of product

Question 6

Solvent extraction is an equilibrium process and is controlled by

Accepted Answer

distribution law

Answer

Law of mass action

Answer

the amount of solute

Answer

the amount of solvent used

Question 7

The comparative rates at which the solutes move in paper chromatography depends on

Accepted Answer

their Rf value

Answer

The size of paper used

Answer

size of the chromatographic tank

Answer

The temperature of the experiment

Question 8

Solvent extraction method is particularly useful technique for separation when the product to be separated is

Accepted Answer

volatile or thermally unstable

Answer

Non volatile or thermally stable

Answer

Non volatile or thermally unstable

Answer

volatile or thermally stable

Question 9

Gooch crucible is made of

Accepted Answer

proclain

Answer

Teflon

Answer

paper

Answer

Glass

Question 10

The drying agent used in dessicator

Accepted Answer

NH4Cl

Answer

P2O5

Answer

AlCl3

Answer

Ag Cl

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