Carbon and its Compounds Chapter 4
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Questions and Answers

Why is the conversion of ethanol to ethanoic acid an oxidation reaction?

Because during the conversion, ethanol gains oxygen atoms.

Can you tell why a mixture of ethyne and air is not used for welding?

A mixture of ethyne and air is not used for welding because it can lead to explosive reactions.

What percentage of carbon is present in the earth's crust and in the atmosphere?

0.02% in the earth's crust and 0.03% in the atmosphere

Compounds of carbon have low melting and boiling points compared to ________ compounds.

<p>ionic</p> Signup and view all the answers

How does carbon achieve noble gas configuration?

<p>By sharing electrons</p> Signup and view all the answers

Covalent compounds are generally good conductors of electricity.

<p>False</p> Signup and view all the answers

What is the electron dot structure of carbon dioxide with the formula CO2?

<p>O=C=O</p> Signup and view all the answers

What is the electron dot structure of a molecule of sulphur made up of eight atoms of sulphur arranged in a ring?

<p>S-S-S-S-S-S-S-S</p> Signup and view all the answers

Draw the electron dot structure for ethyne with the formula C2H2.

<p>H-C\equiv C-H</p> Signup and view all the answers

Can you draw the electron dot structure for cyclohexane with the formula C6H12?

<p>The student should draw a cyclic structure where each carbon has the necessary hydrogen atoms attached.</p> Signup and view all the answers

What are compounds with identical molecular formula but different structures called?

<p>Structural isomers</p> Signup and view all the answers

What is the difference between the molecular formula of propane and butane (C4H10)?

<p>One difference is that propane has 3 carbon atoms and butane has 4 carbon atoms.</p> Signup and view all the answers

Calculate the difference in molecular masses between propane and butane. (Atomic mass of carbon = 12 u, atomic mass of hydrogen = 1 u)

<p>The molecular mass difference is 14 u</p> Signup and view all the answers

What is the formula for ethene?

<p>C2H4</p> Signup and view all the answers

Generate the general formula for alkanes.

<p>The general formula for alkanes is CnH2n+2, where n is the number of carbon atoms in the chain.</p> Signup and view all the answers

Generate the general formula for alkynes.

<p>The general formula for alkynes is CnH2n-2, where n is the number of carbon atoms in the chain.</p> Signup and view all the answers

What is the suffix used to name aldehydes?

<p>al</p> Signup and view all the answers

How many structural isomers can you draw for pentane?

<p>Three</p> Signup and view all the answers

What are the two properties of carbon that lead to the huge number of carbon compounds?

<p>Catenation and tetravalency</p> Signup and view all the answers

How does ethanoic acid react with carbonates and hydrogencarbonates?

<p>Ethanoic acid reacts with carbonates and hydrogencarbonates to give rise to a salt, carbon dioxide, and water. The salt produced is commonly called sodium acetate.</p> Signup and view all the answers

How can you distinguish experimentally between an alcohol and a carboxylic acid?

<p>One experimental method to distinguish between an alcohol and a carboxylic acid is to perform an oxidation test. Carboxylic acids can be oxidized to form carbon dioxide and water, while alcohols do not undergo this reaction.</p> Signup and view all the answers

What are oxidising agents?

<p>Oxidising agents are substances that can accept electrons from other substances in chemical reactions. They cause oxidation of other substances by gaining electrons themselves.</p> Signup and view all the answers

What is the purpose of agitation in cleaning clothes?

<p>Agitation is necessary in cleaning clothes to enhance the interaction between the cleaning agent (soap or detergent) and the dirt particles. It helps in loosening and removing the dirt from the fabric.</p> Signup and view all the answers

Which functional group is found in butanone?

<p>Ketone</p> Signup and view all the answers

Soap molecules have both hydrophilic and hydrophobic ends.

<p>True</p> Signup and view all the answers

Study Notes

Carbon and its Compounds

Bonding in Carbon

  • Carbon compounds have low melting and boiling points, and are poor conductors of electricity
  • The forces of attraction between molecules are not very strong, and the bonding in these compounds does not give rise to any ions
  • Carbon has an atomic number of 6, with four valence electrons, and needs to gain or lose four electrons to attain noble gas configuration
  • Carbon overcomes this problem by sharing its valence electrons with other atoms of carbon or with atoms of other elements

Covalent Bonding

  • Covalent bonds are formed by the sharing of an electron pair between two atoms
  • Covalently bonded molecules have strong bonds within the molecule, but inter-molecular forces are weak
  • Examples of covalent bonding include hydrogen (H2), chlorine (Cl2), oxygen (O2), nitrogen (N2), and methane (CH4)
  • Covalent bonds are represented by a line between the two atoms, and the shared pair of electrons is said to constitute a single covalent bond

Allotropes of Carbon

  • Carbon occurs in different forms in nature, including diamond and graphite, with widely varying physical properties
  • The difference between diamond and graphite lies in the manner in which the carbon atoms are bonded to one another
  • Diamond has a rigid three-dimensional structure, while graphite has a hexagonal array with a double-bond, and is a very good conductor of electricity

Versatile Nature of Carbon

  • Carbon has the unique ability to form bonds with other atoms of carbon, giving rise to large molecules, a property called catenation
  • Carbon compounds can have long chains, branched chains, or rings of carbon atoms, and can be linked by single, double, or triple bonds
  • The carbon-carbon bond is very strong and stable, giving rise to a large number of compounds with many carbon atoms linked to each other

Saturated and Unsaturated Carbon Compounds

  • Compounds of carbon, which are linked by only single bonds between the carbon atoms, are called saturated compounds
  • Examples of saturated compounds include methane, ethane, and propane
  • Compounds of carbon having double or triple bonds between their carbon atoms are called unsaturated compounds
  • Examples of unsaturated compounds include ethene and ethyne### Carbon and its Compounds
  • Carbon is a very friendly element that can form many compounds with hydrogen and other elements

Bonding between Carbon Atoms

  • To satisfy their valencies, carbon atoms can form double or triple bonds between them, resulting in unsaturated carbon compounds
  • Unsaturated carbon compounds are more reactive than saturated carbon compounds

Chains, Branches, and Rings

  • Carbon atoms can form long chains, branches, and rings with other carbon atoms
  • Chains, branches, and rings can be saturated or unsaturated
  • Saturated carbon compounds have single bonds between carbon atoms, while unsaturated carbon compounds have double or triple bonds

Structural Isomers

  • Compounds with the same molecular formula but different structures are called structural isomers
  • Butane (C4H10) has two possible carbon skeletons, which are structural isomers

Functional Groups

  • Functional groups are specific groups of atoms that determine the properties of a carbon compound
  • Functional groups can be halo, hydroxy, aldehyde, ketone, or carboxylic acid groups
  • Functional groups are attached to the carbon chain by replacing hydrogen atoms or other atoms

Homologous Series

  • A series of compounds with the same functional group and differing only in the number of carbon atoms is called a homologous series
  • Compounds in a homologous series have similar chemical properties but varying physical properties
  • The molecular mass of compounds in a homologous series increases with the number of carbon atoms

Nomenclature of Carbon Compounds

  • The names of carbon compounds are based on the name of the basic carbon chain modified by a prefix or suffix
  • The prefix or suffix indicates the nature of the functional group

Chemical Properties of Carbon Compounds

  • Combustion: Carbon and its compounds burn in oxygen to give carbon dioxide, heat, and light
  • Oxidation: Carbon compounds can be easily oxidised on combustion
  • Addition Reaction: Unsaturated hydrocarbons add hydrogen in the presence of catalysts to give saturated hydrocarbons
  • Substitution Reaction: Chlorine can replace hydrogen atoms in saturated hydrocarbons in the presence of sunlight

Fossil Fuels

  • Coal and petroleum are formed from biomass that has been subjected to biological and geological processes
  • Fossil fuels are called fossil fuels because they are formed from ancient plants and animals

Ethanol and Ethanoic Acid

  • Ethanol is an important carbon compound used in various industries
  • Ethanoic acid is formed by the oxidation of ethanol and is used in the production of vinegar and other products### Properties of Ethanol
  • Ethanol (also called alcohol) is a liquid at room temperature
  • Melting point: not mentioned, but can be found in Table 4.1
  • Boiling point: not mentioned, but can be found in Table 4.1
  • Commonly used in medicines such as tincture iodine, cough syrups, and tonics
  • Soluble in water in all proportions
  • Consumption of small quantities can cause drunkenness
  • Long-term consumption can lead to health problems
  • Can react with sodium to produce sodium ethoxide and hydrogen gas

Reactions of Ethanol

  • Reaction with sodium: 2Na + 2CH3CH2OH → 2CH3CH2O–Na+ + H2
  • Reaction to give unsaturated hydrocarbon: CH3CH2OH → CH2=CH2 + H2O (heating ethanol with concentrated sulphuric acid)

Effects of Ethanol on Living Beings

  • Slows down metabolic processes
  • Depresses the central nervous system
  • Causes lack of coordination, mental confusion, drowsiness, and lowered inhibitions
  • Can cause death if consumed in large quantities
  • Methanol is more toxic than ethanol and can cause death even in small quantities

Ethanol as a Fuel

  • Can be produced from sugarcane juice through fermentation
  • Can be used as a cleaner fuel, producing only carbon dioxide and water when burned
  • Dyes are added to ethanol to make it unfit for drinking and distinguish it from drinking alcohol

Properties of Ethanoic Acid

  • Also known as acetic acid
  • Belongs to the group of acids called carboxylic acids
  • 5-8% solution in water is called vinegar and is used as a preservative
  • Melting point: 290 K
  • Can freeze in cold climates, hence the name glacial acetic acid

Reactions of Ethanoic Acid

  • Esterification reaction: CH3COOH + CH3CH2OH → CH3COOC2H5 + H2O
  • Reaction with a base: CH3COOH + NaOH → CH3COONa + H2O
  • Reaction with carbonates and hydrogencarbonates: 2CH3COOH + Na2CO3 → 2CH3COONa + H2O + CO2

Soaps and Detergents

  • Soaps are sodium or potassium salts of long-chain carboxylic acids
  • Dissolve in water and form micelles, which can emulsify oily dirt and remove it
  • Detergents are sodium salts of sulphonic acids or ammonium salts with chloride or bromide ions
  • Do not form insoluble precipitates with calcium and magnesium ions, making them effective in hard water
  • Used in shampoos and cleaning products

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This quiz covers the properties and importance of carbon and its compounds, including their significance in everyday life.

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