11th Class Chemistry Chapter two Short Questions with Answers Solved

Question: 1

Define the term analysis.

Answer: 1

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The process of determination of composition of a substance quantitatively or qualitatively is called analysis.

Question: 2

How does a Gooch crucible increase the rate of filtration?

Answer: 2

2-24

This crucible is made up of porcelain. It has perforated base covered with a filter paper or asbestos mate. Filtration can be done quickly if this crucible is placed in a suction filtering apparatus.

Question: 3

Mention various experiment techniques which are used for the purification of substances?

Answer: 3

3-24

The techniques are as follows:

(i) filtration

(ii) Crystallization

(iii) Sublimation

(iv) Solvent extraction in depends upon the nature of the substances, that which technique is to be used.

Question: 4

How do you justify that qualitative and quantitative analysis are discussed in analytical chemistry?

Answer: 4

4-24

It is that branch of chemistry which gives up analysis of elements and compounds. In qualitative analysis, we come to know about nature of the elements and in quantitative analysis gives us the quantities of different elements in the compound.

Question: 5

Which solvents are mostly used in crystallization?

Answer: 5

5-24

The most commonly used solvents are:

(i) Water

(ii) Rectified spirit

(iii) Absolute alcohol

(iv) Ether

(v) Acetone

(vi) Chloroform

(vii) Carbon Tetra chloride

(viii)Acetic acid

(ix) Petroleum ether

Question: 6

What is analytical chemistry?

Answer: 6

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That branch of chemistry which deals with the quantitative and qualitative analysis is called analytical chemistry.

Question: 7

Define sublimation with an example?

Answer: 7

7-24

The vapourization of a solid directly on heating without passing through the liquid phase and the condensation of these vapours on cooling to solid without passing through liquid phase is called sublimation. Naphethalene, Iodive, NH₄CI, Benzoic acid and Camphor undergo sublimation.

Question: 8

Differentiate between sublimand and sublimate.

Answer: 8

8-24

The solid substance which is being sublimed is called sublimand while the mire solid substance which is obtained after sublimation is called sublimate.

Question: 9

What is ether extraction?

Answer: 9

9-24

Some organic products are prepared in aqueous medium. We have to remove this organic compound from water. For this purpose, ether is added. Two separate layers are produced in the separating funnel. The ether layer contains the organic compound. This ether layer is separated and ether is evaporated.

Question: 10

Concentrated MCI and KMNO. Solutions cannot be filtered by Gooch crucible. Give reason.

Answer: 10

10-24

Conc. HCI and the oxidizing agents like KmnO, react with filter paper. By using Asbestos mate. The above solutions can be filtered.

Question: 11

Give the main characteristics of the solvent used for crystallization.

Answer: 11

11-24

i. The solvent should dissolve a large amount of solute at high temperature.

ii. The solvent should have no chemical reaction with solute.

iii. It should not dissolve the impurities.

iv. It should be cheap.

v. It should not be inflammable.

Question: 12

Testing Question

Answer: 12

12-24

Testing Answer 1

Question: 13

Give the main characteristics of the solvent used for crystallization.

Answer: 13

13-24

i. The solvent should dissolve a large amount of solute at high temperature.

ii. The solvent should have no chemical reaction with solute.

iii. It should not dissolve the impurities.

iv. It should be cheap.

v. It should not be inflammable.

Question: 14

Mention the major steps involved in the crystallization.

Answer: 14

14-24

i.Preparing the saturated solution.

ii.Filtering the impurities.

iii.Cooling of the filtrate.

iv.Collection of crystals.

v.Drying of crystals.

Decolourinzation

Question: 15

Differentiate between filter and filtrate.

Answer: 15

15-24

Filter: Any water insoluble porous material which has a reasonable degree of rigidity and can be used to separate the components from each other is called filter.

Filtrate: That liquid which is collected after passing through the filter medium is called filtrate.

Question: 16

What is solvent extraction?

Answer: 16

16-24

This is a technique in which a solute is separated from the solution. For this purpose, the solution is shaken with another solvent in which the solute is more soluble. Anyhow, the added solvent should not be miscible with thesolution.

Question: 17

What is R_f value?

Answer: 17

17-24

Question: 18

What is meant by mother liquor?

Answer: 18

18-24

The solution which remains behind after the formation of the crystals is called mother liquor.

Question: 19

How the decolourization of undesirable colours is carried out for freshly prepared crystalline substances?

Answer: 19

19-24

The decolorization of_. undesirable colours is carried out by boiling the substance with sufficient amount of powdered animal charcoal in the solvent. Hot solution is filtered in this way charcoal absorbs the coloured impurities and the pure decolorized substance crystallizes on cooling.

Question: 20

Give the main uses of paper chromatrography.

Answer: 20

20-24

i. For the separation of purification of coloured organic compounds.

ii.For checking the purity of the compounds.

iii.In qualitative and quantitative analysis.

iv.For the separation, purification and identification of products of reactions.

Question: 21

Differentiate between stationary and mobile phase?

Answer: 21

21-24

The solvent or the mixture of solvents used for the separation components in chromatography is called mobile phase. The phase over which mobile phase flows is stationary one. Water, ethyl alcohol etc. are some important Mobile phases while silica gel and filter paper are some important stationary phases.

Question: 22

What is the distribution coefficient? To which technique it is applicable.

Answer: 22

22-24

Question: 23

What is called fluted filter paper?

Answer: 23

23-24

That filter paper which has a fan-like arrangement with alternate elevation and depressions at various folds, and is used to increase the rate of filtration is called fluted filter paper.

Question: 24

How desiccator is used to dry the crystals?

Answer: 24

24-24

The prepared crystals are wet and they need drying. In a desiccator, the crystals are spread on the watch glass and placed in a desiccator for several hours. Some drying agents like anhydrous CaCl₂ silica gel or P₂0₅ are used.

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11th Class Chapter two Chemistry Short Questions

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