What are alkanes? Why are they called paraffins?

What are alkanes? Why are they called paraffins?
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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)
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Related questions

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.

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

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.

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.

Explain the physical properties of benzene and its homologues.

Description : Explain the physical properties of benzene and its homologues.

Last 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. ... compounds increases with increase in molecular mass due to increase in van der waals forces.

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.

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.

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.

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.

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.

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 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.

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.

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.

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)

(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.

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.

What are conformations?

Description : What are conformations?

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

Why are alkanes referred to as paraffins?

Description : Why are alkanes referred to as paraffins?

Last Answer : Paraffin is derived from the Latin word meaning ‘less activity’. Alkanes are compounds which undergo few reactions. Hence they are referred to as paraffins.

Saturated hydrocarbons are called - (1) Alkynes (2) Alkenes (3) Alkanes (4) All of the above

Description : Saturated hydrocarbons are called - (1) Alkynes (2) Alkenes (3) Alkanes (4) All of the above

Last Answer : (3) Alkanes Explanation: Carbon compounds which contain just carbon and hydrogen are called hydrocarbons. Among these, the saturated hydrocarbons are called alkanes. The unsaturated hydrocarbons which contain one or more double bonds are called alkenes.

The thermal decomposition of alkanes in the absence of air is called : (a) Combustion (b) Oxidation (c) Cracking (d) Hydrogenation

Description : The thermal decomposition of alkanes in the absence of air is called : (a) Combustion (b) Oxidation (c) Cracking (d) Hydrogenation

Last Answer : Cracking

In the chlorination of alkanes, the first step in which chlorine free radicals are produced is called (a) initiation(b) activation(c) propagation(d) deactivation:

Description : In the chlorination of alkanes, the first step in which chlorine free radicals are produced is called : (a) initiation (b) activation (c) propagation (d) deactivation

Last Answer : initiation

What is the hybridization of carbon atoms in alkanes ?

Description : What is the hybridization of carbon atoms in alkanes ?

Last Answer : Ans. Sp3

Cycloalkanes have the same molecular formula as : (a) Alkanes (b) Alkenes (c) Alkynes (d) Cycloalkenes

Description : Cycloalkanes have the same molecular formula as : (a) Alkanes (b) Alkenes (c) Alkynes (d) Cycloalkenes

Last Answer : Alkenes

Ninhydrin test is given by (a) Carbohydrates (b) Proteins (c) Alkanes (d) Alkenes

Description : Ninhydrin test is given by (a) Carbohydrates (b) Proteins (c) Alkanes (d) Alkenes

Last Answer : Proteins

The high boiling points of alcohols, as compared to the corresponding alkanes, are due to (a) Hydrogen bonding (b) Heavy oxygen atom (c) Water solubility(d) None of these

Description : The high boiling points of alcohols, as compared to the corresponding alkanes, are due to (a) Hydrogen bonding (b) Heavy oxygen atom (c) Water solubility (d) None of these

Last Answer : Hydrogen bonding

Which statements about alkenes and alkanes of corresponding chain lengths is true? (I) Alkenes have slightly lower melting points than alkanes (II) Alkenes have slightly higher melting points than alkanes (III) Alkenes have higher boiling points than alkanes (IV) Alkenes have lower boiling points than alkanes (a) I and III (b) II and IV (c) I and IV (d) II and III

Description : Which statements about alkenes and alkanes of corresponding chain lengths is true? (I) Alkenes have slightly lower melting points than alkanes (II) Alkenes have slightly higher melting points than alkanes (III) Alkenes have higher boiling ... (a) I and III (b) II and IV (c) I and IV (d) II and III

Last Answer : I and III

Which of the following methods can be used to increase the octane rating of gasoline? (a) Adding branched-chain alkanes (b) Adding tetraethyllead (c) Adding aromatic hydrocarbons (d) All of these

Description : Which of the following methods can be used to increase the octane rating of gasoline? (a) Adding branched-chain alkanes (b) Adding tetraethyllead (c) Adding aromatic hydrocarbons (d) All of these

Last Answer : All of these

Consider the three isomeric alkanes n-hexane, 2,3-dimethylbutane, and 2- methylpentane. Which of the following correctly lists these compounds in order of increasing boiling point? (a) 2,3-dimethylbutane < 2-methylpentane < n-hexane (b) 2-methylpentane < n-hexane < 2,3-dimethylbutane (c) 2-methylpentane < 2, 3-dimethylbutane < n-hexane (d) n-hexane < 2-methylpentane < 2,3-dimethylbutane

Description : Consider the three isomeric alkanes n-hexane, 2,3-dimethylbutane, and 2- methylpentane. Which of the following correctly lists these compounds in order of increasing boiling point? (a) 2,3-dimethylbutane < 2- ... < 2, 3-dimethylbutane < n-hexane (d) n-hexane < 2-methylpentane < 2,3-dimethylbutane

Last Answer : 2,3-dimethylbutane < 2-methylpentane < n-hexane

Why is the halogenation of alkanes considered a chain reaction? (a) it occurs quickly. (b) it occurs without the generation of intermediates. (c) each step generates the reactive intermediate that causes the next step to occur. (d) the reaction allows long chains of halogenated alkanes to be formed

Description : Why is the halogenation of alkanes considered a chain reaction? (a) it occurs quickly. (b) it occurs without the generation of intermediates. (c) each step generates the reactive intermediate that causes the next step to occur. (d) the reaction allows long chains of halogenated alkanes to be formed

Last Answer : each step generates the reactive intermediate that causes the next step to occur

Which of the following classes of compounds is unreactive toward sulfuric acid? (a) Alkanes (b) Alcohols (c) Alkenes (d) Alkynes

Description : Which of the following classes of compounds is unreactive toward sulfuric acid? (a) Alkanes (b) Alcohols (c) Alkenes (d) Alkynes

Last Answer : Alkanes

Which of the following reactions can be used to prepare alkanes? (a) Wurtz reaction (b) Wolf-kishner reduction (c) Kolbe's electrolysis (d) All of these

Description : Which of the following reactions can be used to prepare alkanes? (a) Wurtz reaction (b) Wolf-kishner reduction (c) Kolbe's electrolysis (d) All of these

Last Answer : All of these

Which of the following reactions can be used to prepare alkanes? (a) Corey-House synthesis (b) Williamson synthesis (c) Friedel-Crafts reactions (d) None of these

Description : Which of the following reactions can be used to prepare alkanes? (a) Corey-House synthesis (b) Williamson synthesis (c) Friedel-Crafts reactions (d) None of these

Last Answer : Corey-House synthesis

Which of the following alkanes will have the lowest boiling point? (a) n-Heptane (b) Isopentane (c) n-Hexane (d) Neopentane

Description : Which of the following alkanes will have the lowest boiling point? (a) n-Heptane (b) Isopentane (c) n-Hexane (d) Neopentane

Last Answer : Neopentane

Which of the following alkanes will have the highest boiling point? (a) n-Octane (b) Isopentane (c) n-Butane (d) Neopentane

Description : Which of the following alkanes will have the highest boiling point? (a) n-Octane (b) Isopentane (c) n-Butane (d) Neopentane

Last Answer : n-Octane

How do the boiling points of butane, propane, and ethane compare? (a) the boiling point of ethane is greatestb) the boiling point of butane is greatest. (c) the boiling point of propane is greatest. (d) there is no relationship among these three alkanes and their boiling points.

Description : How do the boiling points of butane, propane, and ethane compare? (a) the boiling point of ethane is greatest. b) the boiling point of butane is greatest. (c) the boiling point of propane is greatest. (d) there is no relationship among these three alkanes and their boiling points

Last Answer : the boiling point of butane is greatest.

How does the melting point of propane and ethane compare? (a) the melting point of propane is greater. (b) the melting point of ethane is greater. (c) the melting points are within 5°C of one another. (d) no relationship exists among these alkanes and their melting point

Description : How does the melting point of propane and ethane compare? (a) the melting point of propane is greater. (b) the melting point of ethane is greater. (c) the melting points are within 5°C of one another. (d) no relationship exists among these alkanes and their melting point

Last Answer : the melting point of ethane is greater.

The branching of alkanes that produces symmetrical structures : (a) raises the boiling point ; raises the melting point (b) raises the boiling point ; lowers the melting point (c) lowers the boiling point ; lowers the melting point (d) lowers the boiling point ; raises the melting point

Description : The branching of alkanes that produces symmetrical structures : (a) raises the boiling point ; raises the melting point (b) raises the boiling point ; lowers the melting point (c) lowers the boiling point ; lowers the melting point (d) lowers the boiling point ; raises the melting point

Last Answer : raises the boiling point ; raises the melting point

As the molecular weight of alkanes increases, how do the boiling point and melting point change? (a) boiling point increases ; melting point increases. (b) boiling point increases ; melting point increases. (c) boiling point increases ; melting point decreases (d) boiling point increases ; melting point increases sequentially for alkanes over four carbons.

Description : As the molecular weight of alkanes increases, how do the boiling point and melting point change? (a) boiling point increases ; melting point increases. (b) boiling point increases ; ... decreases (d) boiling point increases ; melting point increases sequentially for alkanes over four carbons.

Last Answer : boiling point increases ; melting point increases sequentially for alkanes over four carbons.

Which statement is false? (a) Many alkanes are soluble in water. (b) All alkanes have a lower density than water. (c) At room temperature some alkanes are liquids, some solids, some gases. (d) All alkanes burn

Description : Which statement is false? (a) Many alkanes are soluble in water. (b) All alkanes have a lower density than water. (c) At room temperature some alkanes are liquids, some solids, some gases. (d) All alkanes burn

Last Answer : Many alkanes are soluble in water

Which of the following show n→ ℿ * electronic transitions? a. Alcohols b. Ethers c.Alkanes d. Aldehydes

Description : Which of the following show n→ ℿ * electronic transitions? a. Alcohols b. Ethers c.Alkanes d. Aldehydes

Last Answer : d. Aldehydes

A family of organic compounds containing only carb and hydrogen and having only single bonds are the: w) alkenes and alkanes x) alkanes and cycloalkanes y) alkynes (pron: AL-kines) and alkenes z) cycloalkanes and alkenes

Description : A family of organic compounds containing only carb and hydrogen and having only single bonds are the: w) alkenes and alkanes x) alkanes and cycloalkanes y) alkynes (pron: AL-kines) and alkenes z) cycloalkanes and alkenes

Last Answer : ANSWER: B -- ALKANES AND CYCLOALKANES