Explain the physical properties of benzene and its homologues.

Explain the physical properties of benzene and its homologues.
by

1 Answer

Answer :

Ans: i. Benzene and its homologous upto eight carbon atoms are colourless liquids with characteristic smell. ii. Aromatic hydrocarbons are immiscible with water but soluble in organic solvents. iii. They are inflammable and burn with sooty flame. iv. The melting and boiling points of aromatic compounds increases with increase in molecular mass due to increase in van der waals forces.
by

Related questions

Out of benzene, m–dinitrobenzene and toluene which will undergo nitration most easily and why?

Description : Out of benzene, m–dinitrobenzene and toluene which will undergo nitration most easily and why?

Last Answer : Ans. -CH3 group is electron donating while –NO2 group is electron withdrawing. Therefore, maximum electron density will be in toluene , followed by benzene and at least in m-dinitrobenzene. Therefore, the ease of nitration decreases in the order: Toluene> benzene> m-dinitrobenzene

Which one is more stable structure of benzene among Kekule and Dewar’s structures?

Description : Which one is more stable structure of benzene among Kekule and Dewar’s structures?

Last Answer : Ans: Kekule’s structure.

How will you demonstrate that double bonds of benzene are somewhat different from that of olefins?

Description : How will you demonstrate that double bonds of benzene are somewhat different from that of olefins?

Last Answer : Ans. The double bonds of olefins decolorize bromine water and discharge the pink colour of Bayer‘s reagent while those of benzene not.

Explain why Grignard reagents do not reacts with alkanes.

Description : Explain why Grignard reagents do not reacts with alkanes.

Last Answer : Ans. In alkanes , the C – H bond has very little polarity . The hydrogen cannot be abstracted by the Grignard reagent.

Is it possible to isolate pure staggered ethane or pure eclipsed ethane at room temperature? Explain .

Description : Is it possible to isolate pure staggered ethane or pure eclipsed ethane at room temperature? Explain .

Last Answer : The energy differences between staggered and eclipsed forms of ethane is just 12.55 kj mol_1 which is easily met by collisions of the molecules at room temperature. Therefore, it is not possible to isolate either pure staggered or pure eclipsed ethane at room temperature.

What effect does branching of an alkane chain has on its boiling point?

Description : What effect does branching of an alkane chain has on its boiling point?

Last Answer : Ans. As branching increases, the surface area of the molecule decreases which results in a small area of contact. As a result, the Van der Waals force also decreases which can be overcome at ... lower temperature. Hence, the boiling point of an alkane chain decreases with an increase in branching.

(a) What effect the branching of an alkane has on its melting point? (L-III) (b) Which of the following has highest boiling point?(L-III) (1) 2-methyl pentane. (2) 2, 3-diethyl butane. (3) 2, 2- dimethyl butane.

Description : (a) What effect the branching of an alkane has on its melting point? (L-III) (b) Which of the following has highest boiling point?(L-III) (1) 2-methyl pentane. (2) 2, 3-diethyl butane. (3) 2, 2- dimethyl butane.

Last Answer : Ans.(a) In general conception, as the branching increases packing of the molecules in the crystals becomes less close and have melting point decreases accordingly. (b) As the branching increases, ... attraction decreases and hence the boiling point decreases. So, 2-methyl pentane has highest B.pt.

Define benzenoids Compounds.

Description : Define benzenoids Compounds.

Last Answer : Ans: Aromatic compounds containing benzene ring.

Define Aromatic Compounds.

Description : Define Aromatic Compounds.

Last Answer : Ans: The Compounds which gives pleasant smell.

What are alkanes? Why are they called paraffins?

Description : What are alkanes? Why are they called paraffins?

Last Answer : Ans. Those hydrocarbons which contain single bond between carbon- carbon are called alkanes. They are called paraffins because they are very less reactive (Latin- Parum= little, affins = affinity)

How will you separate propene from propyne?

Description : How will you separate propene from propyne?

Last Answer : Ans. By passing the mixture through ammonical silver nitrate solution when propyne reacts while propene passes over.

What is Grignard reagent?

Description : What is Grignard reagent?

Last Answer : Ans. Alkyl magnesium halides

What is meant by restricted rotation around of carbon-carbon double bond? What type of isomerism does it lead to?

Description : What is meant by restricted rotation around of carbon-carbon double bond? What type of isomerism does it lead to?

Last Answer : Ans. The carbon-carbon double bond in alkene contains one sigma bond and one pi-bond. The Pibond involves the overlapping of unhybridised p orbital of two carbon atom .The rotation around the ... , the free rotation around C=C double bond is restricted, which gives rise to Geometrical Isomerism.

How will you detect the presence of unsaturation in an organic compound?

Description : How will you detect the presence of unsaturation in an organic compound?

Last Answer : Ans. Generally Unsaturated organic compound decolorize Bayer‘s reagent and Bromine water.

Arrange the following in order of decreasing reactivity towards alkanes. HCl, HBr, HI, HF

Description : Arrange the following in order of decreasing reactivity towards alkanes. HCl, HBr, HI, HF

Last Answer : Ans. HI> HBr> HCl >HF

Name two reagents which can be used to distinguish between ethene and ethyne.

Description : Name two reagents which can be used to distinguish between ethene and ethyne.

Last Answer : Ans. Tollen‘s reagent

Out of ethylene and acetylene which is more acidic and why?

Description : Out of ethylene and acetylene which is more acidic and why?

Last Answer : Ans. Acetylene, due to greater electonegativity of the sp hybridised carbon.

Arrange the following in the increasing order of C-C bond length- C2H6 , C2H4, C2H2

Description : Arrange the following in the increasing order of C-C bond length- C2H6 , C2H4, C2H2

Last Answer : Ans. C2H2 < C2H4 < C2H6

What are the necessary conditions for any system to be aromatic?

Description : What are the necessary conditions for any system to be aromatic?

Last Answer : Ans. A compound is said to be aromatic if it satisfies the following three conditions: (i) It should have a planar structure. (ii) The π-electrons of the compound are completely delocalized in the ring. (iii)The total number ... to (4n + 2), where n = 0, 1, 2 etc. This is known as Huckel s rule.

What are the main constituent of LPG?

Description : What are the main constituent of LPG?

Last Answer : Ans. Butane and isobutane . Both these isomers can be easily liquified and hence can be conveniently transported in iron cylinder.

Which of the following has highest boiling point and why?(L-II) (a) 2 methylpentane (b) 2,3 dimethyl butane (c) 2,2 dimythylbutane

Description : Which of the following has highest boiling point and why?(L-II) (a) 2 methylpentane (b) 2,3 dimethyl butane (c) 2,2 dimythylbutane

Last Answer : Ans. As the branching increases, surface area decreases. As a result, magnitude of Vander Waals forces of attraction decreases and hence the boiling point decreases. Thus, the overall order of decreasing boiling point is: 2 methylpentane (333k) > 2,3 dimethylbutane (331k) > 2,2 dimethylbutane(323k)

Why do the C-C bonds rather than C-H bonds break during cracking of alkanes?

Description : Why do the C-C bonds rather than C-H bonds break during cracking of alkanes?

Last Answer : Ans. Since the bond dissociation energy of C-C bonds (348kj /mol) is lower than bond dissociation energy of C-H bonds (414kj/mol), therefore, during cracking of alkanes, C-C bonds break more early than C-H bonds.

Arrange the three isomers of pentane in increasing order of their boiling points?

Description : Arrange the three isomers of pentane in increasing order of their boiling points?

Last Answer : Ans.2, 2-Dimethylpropane

What do you mean by pyrolysis?

Description : What do you mean by pyrolysis?

Last Answer : The decomposition of a compound by the heat is called pyrolysis. This process when applied to alkanes is known as cracking.

Why are alkanes called paraffins?

Description : Why are alkanes called paraffins?

Last Answer : Paraffin’s means little affinity; alkanes due to strong C-C and C-H bonds are relatively chemically inert.

What are conformations?

Description : What are conformations?

Last Answer : Conformations are spatial arrangements which are obtained by rotation around sigma bonds.

Two adjacent homologues differ by

Description : Two adjacent homologues differ by

Last Answer : 1 carbon atom and 2 hydrogen atoms.

The compound which would have the greatest molar effect on the colligative properties of a dilute solution would be: w) CaCl2 x) NaCl y) C6H12O6 z) Benzene

Description : The compound which would have the greatest molar effect on the colligative properties of a dilute solution would be: w) CaCl2 x) NaCl y) C6H12O6 z) Benzene

Last Answer : ANSWER: W -- CaCl2

(a) Write electron dot diagram for chlorine (At No. 17) and calcium (At No. 20). Show the formation of calcium chloride by transfer of electrons. (b) Identify the nature of above compound’and explain three physical properties of such compound. -Chemistry

Description : (a) Write electron dot diagram for chlorine (At No. 17) and calcium (At No. 20). Show the formation of calcium chloride by transfer of electrons. (b) Identify the nature of above compound’and explain three physical properties of such compound. -Chemistry

Last Answer : (b) It is ionic compound. Physical properties 1.It is hard and solid. 2.It has high melting and boiling point. 3.It soluble in water.

What is the physical properties of sulfuric acid ?

Description : What is the physical properties of sulfuric acid ?

Last Answer : Pure sulfuric acid is a thick oily liquid , which is soluble in water in all proportions. When mixed with water, a lot of heat is emitted. When water is added to sulfuric acid, the water can explode in the ... stirring. If the mixture is too hot, wait. When it is cold, you have to add acid again.

Write three physical & three chemical properties of Hydrogen.

Description : Write three physical & three chemical properties of Hydrogen.

Last Answer : Ans. Physical Properties: (i) Colorless & Odorless gas (ii) Not soluble in water (iii) Low density than air Chemical Properties: (i) Reacts with active metal to form Hydrides (ii) Reacts with nonmetals to form different compound. (iii) Inert at room temperature.

Which of the following improperly describes the physical properties of an alkyne? (a) relatively nonpolar (b) nearly insoluble in water (c) less dense than water (d) insoluble in most organic solvents

Description : Which of the following improperly describes the physical properties of an alkyne? (a) relatively nonpolar (b) nearly insoluble in water (c) less dense than water (d) insoluble in most organic solvents

Last Answer : insoluble in most organic solvents

Write a note on the Physical Properties of Calcium Hydroxide (Slaked lime), Ca(OH)2

Description : Write a note on the Physical Properties of Calcium Hydroxide (Slaked lime), Ca(OH)2

Last Answer : It is a white amorphous powder. It is sparingly soluble in water. The aqueous solution is known as lime water and a suspension of slaked lime in water is known as milk of lime. 

Write anote on the Physical Properties of Sodium hydroxide

Description : Write anote on the Physical Properties of Sodium hydroxide 

Last Answer : Sodium hydroxide is a white, translucent solid. It melts at 591 K. It is readily soluble in water to give a strong alkaline solution. Crystals of sodium hydroxide are deliquescent. The sodium hydroxide solution at the surface reacts with the CO2 in the atmosphere to form Na2CO3. 

For a substance, density, solubility and melting point are examples of: w) physical properties x) amorphous properties y) chemical properties z) potential properties

Description : For a substance, density, solubility and melting point are examples of: w) physical properties x) amorphous properties y) chemical properties z) potential properties

Last Answer : ANSWER: W -- PHYSICAL PROPERTIES

A colligative property depends on: w) chemical properties of particles in system x) physical properties of particles in system y) number of particles present in system z) all of the above

Description : A colligative property depends on: w) chemical properties of particles in system x) physical properties of particles in system y) number of particles present in system z) all of the above

Last Answer : ANSWER: Y -- NUMBER OF PARTICLES PRESENT IN SYSTEM

State and briefly explain any four physical properties of minerals.

Description : State and briefly explain any four physical properties of minerals. 

Last Answer : Minerals have distinguishing physical properties that in most cases can be use to determine the identity of the mineral. Among the various properties crystal, habit, cleavage, hardness, density, luster, ... volume of water) Colour: color is sometimes an extremely diagnostic property of mineral

Enlist the physical properties of soil and explain any one of them.

Description : Enlist the physical properties of soil and explain any one of them.

Last Answer : Physical properties of soil: 1. Void ratio ( e ) 2. Porosity ( n ) 3. Degree of saturation ( s ) 4. Density index ( ID ) 5. Density ( p ) Void ratio ( e ): The ratio of volume of voids (VV = Va + VW) to the total volume (V) of solids is called as void ratio. 

What happens when I treat benzene with chlorine and water?

Description : What happens when I treat benzene with chlorine and water?

Last Answer : It creates chlorine gas, which is very toxic. may I ask why you are asking?

What is the sign of benzene ?

Description : What is the sign of benzene ?

Last Answer : : The signaling of benzene is C₆H₆O₆

Synthetic detergents are made from – (1) Sodium stearate (2) Sodium salt of benzene sulphonic acid (3) Sodium salt of benzene carboxylic acid (4) Sodium palmitate

Description : Synthetic detergents are made from – (1) Sodium stearate (2) Sodium salt of benzene sulphonic acid (3) Sodium salt of benzene carboxylic acid (4) Sodium palmitate

Last Answer : (2) Sodium salt of benzene sulphonic acid Explanation: Synthetic detergents are made from sodium salt of benezene sulphonic acid.

Nail polish remover contains? (1) benzene (2) acetic acid (3) acetone (4) petroleum ether

Description : Nail polish remover contains? (1) benzene (2) acetic acid (3) acetone (4) petroleum ether

Last Answer : (3) Acetone Explanation: Acetone can remove artificial nails made of acrylic or cured gel. A less harsh nail polish remover is ethyl acetate, which often also contains isopropyl alcohol. Ethyl acetate is usually the original solvent for nail polish itself.

An example of heterocyclic compound is – (1) Naphthalene (2) Furan (3) Benzene (4) Anthracene

Description : An example of heterocyclic compound is – (1) Naphthalene (2) Furan (3) Benzene (4) Anthracene

Last Answer : (2) Furan Explanation: A heterocyclic compound is a cyclic compound that has atoms of at least two different elements as members ails ring (s). Furan is a heterocyclic organic compound, consisting of a five-membered aromatic ring with four carbon atoms and one oxygen.

Benzene cannot undergo – (1) Substitution (2) Addition (3) Elimination (4) Oxidation

Description : Benzene cannot undergo – (1) Substitution (2) Addition (3) Elimination (4) Oxidation

Last Answer : (3) Elimination Explanation: Benzene can not undergo Elimination reaction.

Which of the following is present in Nail polish remover? (1) Citric acid (2) Acetone (3) Ethylene (4) Benzene

Description : Which of the following is present in Nail polish remover? (1) Citric acid (2) Acetone (3) Ethylene (4) Benzene

Last Answer : (2) Acetone Explanation: Acetone can also remove artificial nails made of acrylic or cured gel. An alternative nail polish remover is ethyl acetate, which often also contains isopropyl alcohol.

Which have the maximum density? (1) Water (2) Benzene (3) Ice (4) Chloroform

Description : Which have the maximum density? (1) Water (2) Benzene (3) Ice (4) Chloroform

Last Answer : (1) Water Explanation: Water has its maximum density of 1g/cm3 at 4 degrees Celsius. When the temperature changes from either greater or less than 4 degrees, the density will become less than 1 g/cm3.

Which hydrocarbons are the major constituents of 'LPG'? (1) Methane and Ethane (2) Propane and Butane (3) Pentane and Benzene (4) Only Methane

Description : Which hydrocarbons are the major constituents of 'LPG'? (1) Methane and Ethane (2) Propane and Butane (3) Pentane and Benzene (4) Only Methane

Last Answer : (2) Propane and Butane Explanation: Cooking gas, also known as Liquefied Petroleum Gas (LPG) is primarily propane (C3Hg) and butane (C4H10).

Chemical name of Gammaxane is - (1) Toluene (2) Chloro benzene (3) Aniline (4) Benzene hexachloride

Description : Chemical name of Gammaxane is - (1) Toluene (2) Chloro benzene (3) Aniline (4) Benzene hexachloride

Last Answer : (4) Benzene hexachloride Explanation: Gammexane is an insecticide that is the gamma isomer of benzene hexachloride. It is also known as lindane. Benzene hexachloride is any of several stereoisomers of 1,2,3,4,5,6- hexachlorocyclohexane formed by the lightinduced addition of chlorine to benzene.

Adding Cl2 to benzene in the presence of AlCl3 is an example of – (1) Elimination reaction (2) Substitution reaction (3) None of the options (4) Addition reaction

Description : Adding Cl2 to benzene in the presence of AlCl3 is an example of – (1) Elimination reaction (2) Substitution reaction (3) None of the options (4) Addition reaction

Last Answer : (2) Substitution reaction Explanation: The reaction between benzene and chlorine in the presence of a catalyst such as aluminium chloride gives Chlorobenzene. This reaction is an example of electrophilic substitution ... since one of the hydrogen atoms on the ring is replaced by a chlorine atom.

Nail polish remover contains? (1) Benzene (2) acetic acid (3) acetone (4) petroleum ether

Description : Nail polish remover contains? (1) Benzene (2) acetic acid (3) acetone (4) petroleum ether

Last Answer : (3) acetone Explanation: Acetone can remove artificial nails made of acrylic or cured gel. A less harsh nail polish remover is ethyl acetate, which often also contains isopropyl alcohol. Ethyl acetate is usually the original solvent for nail polish itself.