Samacheer Class 10 Science - Types of Chemical Reactions

Reason: Calcium and magnesium salts of detergents are water soluble.
Answer: i) A and R are correct, R explains the A.

hydrocarbons.
Reason: Hydrocarbons consist of covalent bonds.
Answer: iv) A and R are correct, R doesn’t explains A.

Simplest Ketone is acetone
Structural formula - CH3COCH3

(i) Propane : acyclic
(ii) Benzene : Cyclic, Aromatic, Compound
(iii) Cyclo butane : Alicyclic
(iv) Furan : Hetetrocyclic

Ethanoic acid is prepared in large scale, by the oxidation of ethanol in the presence of alkaline potassium permanganate or acidified potassium dichromate.
CH3CH2OH [Ethanol] \rightarrow KMnO4/OH- 2[O] \rightarrow CH3CQQH [Ethanoic acid] + H2O

Some detergents having a branched hydrocarbon chain are not fully biodegradable by micro­organisms present in water. So, they cause water pollution.
We have to limit our use of detergents. Using the minimum amount of detergent while washing clothes or dishes will reduce the pollution. It is better to use only phosphate free detergents.

Soap
i. It is a sodium salt of long chain fatty acids.
ii. The ionic part of a soap is -- COO-Na+.
iii. It is prepared from animal fats or vegetable oils.
iv. Its effectiveness is reduced when used in hard water.
v. It forms a scum in hard water.
vi. It has poor foaming capacity.
vii. Soaps are biodegradable.
Detergent
i. It is sodium salt of sulphonic acids.
ii. The ionic part in a detergent is -- SO-Na+.
iii. It is prepared from hydrocarbons obtained from crude oil.
iv. It is effective even in hard water.
v. Does not form a scum in hard water.
vi. It has rich foaming capacity.
vii. Most of the detergents are non-biodegradable.

Homologus series is a group or a class of organic compounds having same general formula & similar chemical properties in which the successive numbers differ by a -CH2 group.
Characteristics of homologous series :
(i) Each member of the series differs from the preceding or succeeding member by one methylene group (-CH2) and hence by a molecular mass of 14 amu.
(ii) All members of a homologous series contain the same elements and functional group.
(iii) They are represented by a general molecular formula. e.g. Alkanes, CnH2n+2.
(iv) The members in each homologous series show a regular gradation in their physical properties with respect to their increase in molecular mass.
(v) Chemical properties of the members of a homologous series are similar.
(vi) All the members can be prepared by a common method.

Step 1: The parent chain consists of 3 carbon atoms. The root word is ‘Prop’.
Step 2: There are single bonds between the carbon atoms of the chain. So, the primary suffix is ‘ane’.
Step 3: Since, the compound contains - OH group, it is an alcohol. The carbon chain is numbered from the end which is closest to -OH group. (Rule 3)
3 2 1
CH3 - CH2 - CH2 - OH
Step 4: The locant number of -OH group is 1 and thus the secondary suffix is ‘1-ol’.
$The name of the compound is Prop + ane + (1 -ol) = Propan - 1- ol$
Note: Terminal ‘e’ of ‘ane’ is removed as per Rule 5

Ethanol Manufacture: Ethanol is manufactured in industries by the fermentation of molasses, which is a by-product obtained during the manufacture of sugar from sugarcane. Molasses is a dark coloured syrupy liquid left after the crystallization of sugar from the concentrated sugarcane juice. Molasses contain about 30% of sucrose, which cannot be separated by crystallization. It is converted into ethanol by the following steps:
(i) Dilution of molasses : Molasses is first diluted with water to bring down the concentration of sugar to about 8 to 10%.
(ii) Addition of Nitrogen source : Molasses usually contains enough nitrogenous matter to act as food for yeast during the fermentation process. If the nitrogen content of the molasses is poor, it may be fortified by the addition of ammonium sulphate or ammonium phosphate.
(iii) Addition of Yeast : The solution obtained in step (ii) is collected in large ‘fermentation tanks’ and yeast is added to it. The mixture is kept at about 303K for a few days. During this period, the enzymes invertase and zymase present in yeast, bring about the conversion of sucrose into ethanol.
The fermented liquid is technically called wash.
Distillation of ‘Wash’ : The fermented liquid (i.e. wash), containing 15 to 18 percent alcohol, is now subjected to fractional distillation. The main fraction drawn is an aqueous solution of ethanol which contain 95.5% of ethanol and 4.5% of water. This is called rectified spirit. This mixture is then refluxed over quicklime for about 5 to 6 hours and then allowed to stand for 12 hours. On distillation of this mixture, pure alcohol (100%) is obtained. This is called absolute alcohol.

(i) Ethanoic acid reacts with sodium hydroxide to form sodium ethanoate and water.
CH3COOH + NaOH \rightarrow CH3COONa + H2O
(ii) Ethanoic acid reacts with sodium bicarbonate and liberates CO2, with brisk effervescence.
CH3COOH + NaHCO3 \rightarrow CH3COONa + CO2↑ + H2O
(iii) Ethanol is oxidized to ethanoic acid with alkaline KMnO4. or acidified K2Cr2O7
(iv) Ethanol is highly inflammable liquid. It burns with oxygen to form carbon dioxide and water.
C2H5OH + 3O2 \rightarrow 2CO2 + 3H2O
Ethanol + Oxygen \rightarrow carbon dioxide + Water

(i) A soap molecule contains two chemically distinct parts that interact differently with water. It has one polar end, which is a short head with a carboxylate group (-COONa) and one non-polar end having the long tail made of the hydrocarbon chain.
(ii) The polar end is hydrophilic (Water loving) in nature and this end is attracted towards water. The non-polar end is hydrophobic (Water hating) in nature and it is attracted towards dirt or oil on the cloth, but not attracted towards water. Thus, the hydrophobic part of the soap molecule traps the dirt and the hydrophilic part makes the entire molecule soluble in water.
(iii) When a soap or detergent is dissolved in water, the molecules join together as clusters called 'micelles’. Their long hydrocarbon chains attach themselves to the oil and dirt. The dirt is thus surrounded by the non-polar end of the soap molecules. The charged carboxylate end of the soap molecules makes the micelles soluble in water. Thus, the dirt is washed away with the soap.

(i) Draw its structural formula.
(ii) Give its IUPAC name. - 2-Butanol.
(iii) Is it saturated or unsaturated? - Saturated.

(i) Identify the compound ‘A’. - Ethanoic acid (acetic acid).
(ii) Write the chemical equation for its reaction with ethanol to form compound ‘B’.
CH3COOC,Hs (Ethyl acetate).
C2H5OH [Ethanol] + CH3COOH [Ethanoic acid] --conc-H2SO4\rightarrow CH3COOC2H5 [Ethyl ethanoate] + H2O
(iii) Name the process. - Esterification.
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