Rajasthan Board RBSE Class 10 Science Important Questions Chapter 4 Carbon and Its Compounds Important Questions and Answers.
RBSE Class 10 Science Chapter 4 Important Questions Carbon and Its Compounds
Objective Type Questions
The allotrop of carbon in which free electrons are present is –
The side product in the process of soap formation is –
(c) Fatty acid
Total number of bonds present in Ethylene (Ethene) are –
The compound formed by the Hydration of Ethene is—
The formation of Acetic acid from Ethanol is –
Higher Homologue of butane is –
IUPAC name of Acetone (CH3COCH3) is –
(d) Ethanoic acid
IUPAC name of CH3-CH2COOH is –
(a) Methanoic acid
(c) Popanoic acid
(c) Popanoic acid
Generally detergents are –
(a) RCOO Na
(b) R COOK
Very Short Answer Type Questions
Write the balanced equation of combustion of methane.
The balanced equation of combustion of methane is as under –
CH4+ 2O2 → CO2 + 2H2O
(Methane) (Oxygen) (Carbon dioxide) (Water) + Heat and Light
What is the general formula of Alkenes?
The general formula of Alkenes is CnH2n
What is ‘fullerenes’?
Fullerenes are carbon allotropes in which the carbon atoms are arranged in the shape of a football.
What is the electron dot structure of methane (CH4)?
Ans. The electron dot structure of methane is as under –
Write the name and chemical formula of organic acid present in Vinegar.
organic acid present in vinegar is acetic acid, chemical formula of which is
Write the two uses of Ethanoic acid.
To make ester, vinegar.
In the preparation of soap.
Name the following compounds
CH3 – CH = CH2 Propene (Propylene)
CH3 – CH = O Ethanal (Acetaldehyde)
Write the name of compound CH3COOH and identify the functional group of it.
The name of compound CH3 COOH is Acetic acid (Ethanoic acid) and its functional group is -COOH (Carboxylic acid)
Give the name of following compounds –
1. A alcohol derived from ethane
2. A ketone derived from butane
3. A carboxylic acid derived from methane.
- Methanoic acid.
A organic compound bums with sooty flame, then this compound is saturated or unsaturated?
Write the name of functional group -COOH.
Carboxylic acid group.
Write the structure of butanone.
Covalent compounds are weak conductor of electricity, why?
Free ions or electrons which are essential for conduction of electricity are not present in covalent compounds so these are weak conductor of electricity.
Which type of oils should be used for the cooking of food?
Oils containing unsaturated fatty acids should be used for the cooking of food.
Write the complete name of CNG.
The complete name of CNG is Compressed Natural Gas.
Why coal and petroleum are called fossil fuels ? .
Coal and petroleum have been formed from biomass, therefore they are called fossil fuels.
Give the uses of esters.
Generally, esters are sweet smelling substances so these are used in making perfumes and as flavouring agents.
What is the geometry of carbon atom.
The geometry of carbon atom is tetrahedral.
What is the general formula of Alkyne series?
The General formula of alkyne series is CnH2n_2.
Which type of compounds are present in detergents?
Detergents are generally ammonium or sulphonate salts of long chain carboxylic acids.
Write the full form of IUPAC.
IUPAC = International Union of Pure and Applied Chemistry.
What will the formula of methyl acetylene?
The formula of methyl acetylene is CH3—C = CH. This is called Propyne.
What are soaps?
The soaps are sodium (RCOONa) or potassium (RCOOK) salt of long chain carboxylic acids.
What is covalent bond?
The bond formed by the sharing of one electron pair between two atoms is called covalent bond. This is very strong bond.
Write the name of first 6 members of Alkane series.
Methane (CH4), Ethane (C2H6), Propane (C3H8), Butane (C4H10), Pentane (C5H12) and Hexane (C6H14) are starting 6 members of Alkane series.
What is Hetero atom?
The element which replace one or more hydrogen atoms in a hydrocarbon chain is called hetero atom. Example halogen (F, Cl, Br, I), oxygen, nitrogen and sulphur.
What is suffix of functional group Ketone?
The suffix of ketone (>C = O) is -one.
What is oxidising agent?
The substance which oxidise the other substance and itself is reduced, is called oxidising agent. This substance give oxygen for oxidation.
What is catalyst?
The substance that change the rate of reaction but itself will not participate in the reaction is called catalyst.
Which compound is called alcohol?
Generally, ethanol (C2H5OH) is called alcohol. This is important ingredient of all alcoholic drinks.
What is the valency of carbon ?
Carbon is tetravalent because it was four valence electrons.
Why is carbon called a very friendly element ?
Carbon easily forms covalent bonds with other carbon atoms as well as with hydrogen, halogen, oxygen, nitrogen and sulphur, hence, it is called a very friendly element.
Why do gas/kerosene stove used is homes have holes ?
The gas/kerosene stove used at home has inlets for air so that a sufficient oxygen rich mixture is burnt to give a clean blue flame.
What will happen if saturated hydrocarbons are bum with limited supply of air ?
Burning saturated hydrocarbons in limiting supply of air results in incomplete combustion giving a sooty flame.
What are the important uses of ethanol?
Ethanol is a good solvent so it is used in medicines such as tincture iodine, cough syrups and many tonics.
Write the equation of reaction of acetic acid with NaOH.
What is the IUPAC name of C4H9OH?
The IUPAC name of C4H9OH is butanol.
Why the pure acetic acid is called glacial acetic acid?
The melting point of pure acetic acid is 290 K hence it often freezes during winter in cold climates so this is called glacial acetic acid.
What is hydrocarbon?
The organic compounds which have only carbon and hydrogen are called hydro-carbon.
Write the types of carbon chains?
In the carbon compounds, carbon chains are straight, branched or in the forms of rings. These compounds may be saturated or unsaturated.
Who prepare the urea from ammonium cyanate, first time?
Fredrich Wholar (1828) have prepared the urea from ammonium cyanate, first time.
What are Alkane, Alkene and Alkyne?
Saturated hydrocarbons (C – C) are called Alkanes and unsaturated hydro-carbons having (C = C) and (C = C) are called Alkenes and Alkynes successively.
Carbon compounds are bad conductor of electrictiy and melting point and boiling point of these is low, why?
Ions are not present in carbon compounds so attraction between molecules is weak hence these are bad conductor of electricity with low melting point and boiling point.
What is the use of methane (CH4)?
Ans. Methane (CH4) is used as fuel and this is the main ingredient of bio gas and compressed natural gas (C.N.G.).
What are ‘structural isomers’ ?
Compounds with identical mole-cular formula but different structures are called structural isomers.
On what does the nature of the flame coming from the burning of hydrocarbon depends upon ?
Saturated hydrocarbons will generally give a clean flame while unsaturated carbon compounds will give a yellow flame with lots of black smoke.
What presence makes soap uneffective in hard water?
The presence of calcium and magnesium salts in hard water makes soap uneffective.
Short Answer Type Questions
How many structural isomers can be drawn for butane?
Butane (C4H10) have two isomers –
1. n-butane (normal butane)
2. Iso-butane (normal butane)
Write the structural formula and functional group of Acetic acid and Ethyl Alcohol.
1. Acetic acid –
2. Ethyl Alcohol –
Write the difference between soap and detergent.
Difference between soap and detergent –
|1. Soaps are sodium or potassium salt of fatty acids (Carboxylic acids).||Detergents are ammonium or sulphonate salts of long chain carboxylic acid.|
|2. Soap does not form foam with hard water.||Detergents are also effective in hard water and forms foam.|
|3. Soap is prepared from vegetable oil or animal fat.||Synthetic detergents are formed by coal and hydrocarbons of petroleum.|
|4. Soap does not create water pollution.||Detergents creates water pollution.|
How the carbon form a large number of compounds?
Explain the versatile nature of Carbon.
The versatile nature of carbon is due to the following reasons—
Tetravalency of Carbon:
Since carbon has a valency of four, it is capable of bonding with four other atoms of carbon or atoms of some other mono-valent elements. Compounds of carbon are formed with oxygen, hydrogen, nitrogen, sulphur, chlorine and many other elements giving rise to compounds with specific properties which depend on the elements other than carbon present in the molecule. .
The bonds that carbon forms with most other elements are very strong making these compounds exceptionally stable. Small size of Carbon: One reason for the formation of strong bonds by carbon is its small size. This enables the nucleus to hold on to the shared pairs of electrons strongly.
Calination: Carbon has the unique ability to form bonds with other atoms of carbon, giving size to large molecules. This property is called catenation.
What is Alkyne? Write the general formula of this and write the name and electronic structure of simplest Alkyne also.
Alkynes – Unsaturated carbon compounds formed by the combination of carbon and hydrogen, which have one triple bond is called Alkyne.
The general formula of Alkyne is CnH2n-2.
The first member of this series is Ethyne. The electronic structure of this is as under –
What is the importance of carbon? Explain.
Carbon is very important in element and combined state both. Carbon is versatile element. Food, clothes, medicines, books, or many of the things are all based on carbon. In addition, all living structures are also based on carbon. The amount of carbon present in the earth’s crust and in the atmosphere is quite meagre. The earth’s crust has only 0.02% carbon in the form of minerals [like carbonates (CO32-)] hydrogen – carbonates (HCO3–), coal and petroleum] and the atmosphere has 0.03% of carbon dioxide. In spite of this small amount of carbon available in nature, the importance of carbon seems to be immense.
Covalent bond is present in carbon compounds, not ionic, why? Explain it.
The atomic number of carbon is 6 (2, 4). Its outer shell has four electrons. During bond formation atoms have tendency to attain noble gas configuration. Elements forming ionic compounds archieve this by either gaining or losing electrons from file outermost shell. Carbon has four electrons in its outermost shell and needs to gain or lose four electrons to attain noble gas configuration. If it were to gain or lose electrons –
1. It could gain four electrons forming C4- anion. But it would be difficult for the nucleus with six protons to hold on to ten electrons.
2. It could lose four electrons forming C4+ cation. But it would require a large amount of energy to remove four electrons leaving behind a carbon cation with six protons in its nucleus holding on to only- two electrons.
So the carbon compounds are not ionic and carbon forms covalent bond by sharing its valence electrons with other atoms of carbon or with atoms of other elements. Due to which both the atoms attains the noble gas configuration.
Explain the formation of coal and petroleum.
Coal and petroleum have been formed from biomass which has been subjected to various biological and geological processes. Coal is the remains of trees, ferns, and other plants that lived millions of years ago. These were crushed into the earth, perhaps by earthquakes or volcanic eruptions. They were pressed down by layers of earth and rock. They slowly decayed into coal. Oil and gas are the remains of millions of tiny plants and animals that lived in the sea. When they died, their bodies sank to the sea bed and were covered by silt. Bacteria attacked the dead remains, turning them into oil and gas under the high pressures.
How the covalent bond is formed in H2 and Cl2 molecule? Explain.
(1) H2-The atomic number of hydrogen is one. Hence hydrogen has one electron in its K shell and it requires one more electron to fill the K shell. So two hydrogen atoms share their electrons to form a molecule of hydrogen (H2). This allows each hydrogen atom to attain the electronic configuration of the nearest noble gas, helium and the shared pair of electrons forms a single bond between the two atoms of hydrogen.
(2) Cl2 – Similar to H2, Cl2 also have single bond because the atomic number of chlorine atom is 17 (2, 8, 7) and becomes 8 electrons in the outermost shell of it by the sharing of one electron (configuration similar to Ar).
How the covalent bond is formed in O2 and N2? Explain.
The atomic number of oxygen is eight so an atom of oxygen has six electrons in its L shell and it requires two more electrons to complete its octet. But the atomic number of nitrogen is seven so it requires three more electrons to complete its octet.
So each atom of oxygen shares two electrons with another atom of oxygen and each atom of nitrogen shares three electrons with another atom of nitrogen and forms double and triple bond successively and inert gas configuration is attained.
Why alkaline potassium permanganate and acidified potassium dichro-mate are known as ‘oxidising’ agents?
Alkaline potassium permanganate or acidified potassium dichromate are oxidising alcohols to acids, that is, adding oxygen to the starting material. Hence they are known as oxidising agents.
What are hetroatom ? Give example ?
Carbon forms bonds with other elements such as halogens, oxygen, nitrogen and sulphur. In a hydrocarbon chain, one or more hydrogens can be replaced by these elements, such that the valency of carbon remains satisfied. In such compounds, the element replacing hydrogen is referred to as hetro atom.
How the inert gas conifguration of atoms is attained in CH4, NH3 and H2O. represent it with electron dot structure.
(1) Methane (CH4)
(2) NH3 (Ammonia)
In the formation of these molecules C, N and O attains the configuration similar to Ne (2, 8) and H(2), similar to He.
What is functional group? Explain with examples.
Functional group – Those hetero-atom or group of atoms which represents the specific properties to carbon compound is called functional group.
Some functional groups in carbon compounds are as under –
Free valency or valencies of the group are shown by single lines by which functional group is attached the carbon chain
Why it is stated in some adver-tisements that some vegetable oils are ‘healthy’ ?
Generally, animal fats contain saturated fatty acids which are said to be harmful for health. Whereas vegetable oils generally have long unsaturated carbon chains therefore, they are called healthy.
In the homologous series, a gradation in physical properties is seen. Why?
As the molecular mass increases in any homologous series, a gradation in physical properties is seen. This is because the melting and boiling points increase with increasing molecular mass.
Calculate the difference in formulae and molecular masses.
1. CH3-OH and C2H5OH
2. C2H5OH and C3H7OH
3. C3H7OH and C4H9OH
(b) Is any similarities in these three?
(c) To prepare a family, arrange these Alcohols in the increasing order of carbon atoms. Is this may the called a family of homologous series?
(a) There is difference of CH2 in these formulae so the difference in molecular mass is 14.
(b) All the three group belongs to same homologous series because same functional group (-OH) substitutes Hydrogen, present in the carbon chain.
These compounds belongs to same Homologous series (family) which is Alcohol series.
Define Alkane, Alkene and Alky- ne and write the general formula of these.
1. Alkane – The saturated carbon compounds (Hydrocarbons) formed by the combination of carbon and hydrogen, which have single bond between carbon atoms are called Alkanes. General formula of Alkanes is COnH2n+2 where n = 1, 2, 3, 4,….
2. The unsaturated hydrocarbons formed by the combination of carbon and hydrogen which have double bond between, carbon atoms are called Alkenes.
General formula of Alkenes is CnH2n where n = 2, 3, 4 ….
3. The unsaturated hydrocarbons formed by the combination of carbon and hydrogen having triple bond between carbon atoms are called Alkynes.
General formula of Alkynes is CnH2n- 2 where n = 2, 3, 4 ….
The coal or charcoal in an ‘angithi’ sometimes just glows red and gives out heat without a flame. Why ?
This is because a flame is only produced when gaseous substances burn. When wood or charcoal is ignited, the volative substances present vapourise and bum with a flame in the beginning.
(a) Two Alkanes have 4 and 6 carbon atoms successively then what will be the physical state of these at room temperature?
(b) Write the formula and name of third and fifth member of Homologous series with general formula CnH2n- 2 .
(a) Alkane having four carbon atoms is butane, which is gas at room temperature but the Alkane having six carbon atoms is hexane which is liquid at room temperature.
(b) The general formula CnH2n- 2 belongs to Alkyne series which starts from n = 2. So will be equal to four. For the third member of this series and n will be equal to six for fifth member. So the third member of this series is butyne (C4H6) and fifth member of this series is hexyne (C6H10).
A organic compound A having molecular formula C2H6O gives Carboxylic Acid B. On oxidation which have the number of carbon atoms equal to A. Compound A is used by doctors for sterili-sation of skin then what is the name of compound A and B and write the equation of the reaction for the formation B from A.
So the B is organic acid having two carbon atoms with —COOH group. So B is CH3OCOOH carboxylic acid is formed by the oxidation of alcohol and alcohol is used to sterilise the skin. So the compound A (C2H6O) is alcohol and equation of the chemical reaction for the formation of B.
From A is as under –
What is ‘denatured alcohol’ ?
What do you understand by ‘denatu- ration’ of alcohol’ ?
Ethanol is an important industrial solvent. To prevent the misuse of ethanol produced for industrial use, it is made unfit for drinking , by adding poisonous substances like methanol to it. Dyes are also added to colour the alcohol blue so that it can be identified easily. This is called denatured alcohol.
The boiling points of three saturated Hydrocarbon A, B and C are – 162°C, – 42.2°C and – 0.5°C. Successively then which hydrocarbon have maxi-mum number of carbon atoms?
Compound C have maximum number of carbon atoms because the boiling point of it is maximum. Molecular mass increases with increase in number of carbon atoms so attraction force between molecules increases as a result melting point and boiling point also increases.
Write the two tests which represent the acidic property of acetic acid (CH3COOH).
These tests are performed to represent the acidic property of acetic acid.
(1) Litmus Test – When few drops of acetic acid are added on blue litmus then it becomes red which proves the acidic property of it.
(2) Sodium bicarbonate Test – When solution of sodium bicarbonate is added in acetic acid, CO 2 gas is liberated with effervescence which again proves the acidic property of acetic acid.
A neutral organic compound A, having molecular formula C2H6O, gives acidic compound B on oxidation with potassium-dichromate and sulphuric acid. When B again reacts with A in presence of hot and concetrate H2SO4 then a compound with sweet smell is formed. Identify the A, B and C and write the equations of the reactions.
B is a acidic compound, which forms sweet smelling compound C by the reaction with A. So, C should be an ester and A will be an alcohol. So,
A = C2H5OH (Ethanol)
B = CH3COOH (Ethanoic acid)
C = CH3COOC2H5 (Ethyl Ethanoate)
The reactions will be as follows –
(a) The compounds of following formula belongs to which homologous series?
(b) What is the structural difference between molecules of Aldehyde and Ketone?
(a) (i) This compound belongs to amino series which have functional group, – NH2.
(ii) This compound belongs to ketone series.
(b) Molecule of aldehyde and ketone both have >C = O (Carbonyl) group. In case of aldehyde one valance of carbonyl group is satisfied by H and another one by alkyl group so the functional group of aldehyde is -CHO but in case of ketone both the valancies of >C = O group are satisfied by alkyl group.
(a) Ethanol is soluble in water or not?
(b) What happens when ethanol reacts with hot and concentrated H2SO4?
(a) Ethanol is liquid at room temperature and this is soluble in water. Ethanol can be mixed in water in any proportion.
(b) When ethanol reacts with hot and concentrated H2OSO4, ethene is formed due to dehydration of it.
In this reaction the concentrated sulphu-ric acid act as dehydrating agent which removes water from ethanol.
What is ‘esterification’. Explain.
Esters are most commonly formed by reaction of an acid and an alcohol. Ethanoic acid reacts with absolute ethanol in the presence of an acid catalyst to give an ester. This is called esterification.
What is ‘Saponification’ ? What is its use ?
On treating ester with sodium hydroxide, which is an alkali, the ester is converted back to alcohol and sodium salt of carboxylic acid. This reaction is known as saponification.
This reaction is used in the preparation of soap. Soaps are sodium or potassium salts of long chain carboxylic acid.
How do Ethanol and Methanol affect living beings? Explain.
Effect of Ethanol (C2H5OH) and Methanol (CH3OH) on living beings— When large quantity of ethanol is consumed, it tends to slow metabolic processes and to depress the central nervous system. This results in lack of coordination, mental confusion, drowsiness, lowering of the normal inhibitions, and finally stupour. Although a person feel relaxed but does not realise that his sense of judgement, sense of timing, and muscular coordination have been seriously impaired.
Intake of methanol in very small quantities can cause death. Methanol is oxidised to methanal in the liver. Methanal reacts rapidly with the components of cells. It causes the protoplasm to get coagulated. Methanol also affects the optic nerve, causing blindness.
Give the use of Alcohol as a fuel.
Use of Alcohol as a fuel: Sugar-cane plants are the most efficient convertors of sunlight into chemical energy. Sugarcane juice is used to prepare molasses which isfermented to give alcohol (ethanol). Some countries use alcohol as an additive in petrol since it is a cleaner fuel wich gives rise to only carbon dioxide and water on burning in sufficient oxygen. ‘
Detergent can be used in hard water also. Why?
Detergents are ammonium or sulphonate salts of long chain carboxylic acids. The charged ends of these compounds do not form unsoluble precipitates with the calcium and magnesium ions in hard water. Thus, they remain effective in hard water also. Detergents are generally used to make shampoos and products for cleaning clothes.
Essay Type Questions
Write the different Allotropes of carbon. Give the property, structure and uses of these Allotropes.
The’ carbon occurs in different forms in nature with different physical properties. Due to the difference in the manner in which the carbon atoms are bonded to each other chemical properties of allotropes are same. Different allotropes of carbon are as follows –
1. Diamond: In diamond, each carbon atom is bonded to four other carbon atoms forming a rigid three-dimensional structure. Diamond is the hardest substance known.
2. Graphite: In graphite, each carbon atoms is bonded to three other carbon atoms in the same plane giving a hexagonal structure. One of these bonds is a double bond and thus the valency of carbon is satisfied. Graphite structure is formed by the hexagonal structures being placed in layers one above the other.
The distance between carbon atoms of different layers is more due to hexagonal structure. So the possiblity of formation of covalent bonds between carbon atoms of opposite layers is negligible and fourth valance electron of carbon atoms remains almost free. So the flow of electrons in graphite is easy and it becomes good conductor of electricity. Graphite is smooth and slippery also.
3. Diamonds can be synthesised by subjecting pure carbon to very high pressure and temperature. These synthetic diamonds are small in size but are indistinguishable from natural diamonds.
4. Fullerenes form another class of allotropes of carbon. The first one to be identified was C-60 which has carbon atoms arranged in the shape of a football.
What is saturated hydrocarbon? Give the specific name for this series and write the structure of first six members of it.
Saturated hydrocarbon – Carbon compounds formed by carbon and hydrogen which have single bond between carbon atoms are called saturated hydrocarbons.
Saturated hydrocarbons are known as Aikanes. The general formula of Aikanes is CnH2n+2 where n = 1, 2, 3, 4 …. The first six members of Alkane series are methane, ethane, propane, butane, pentane and hexane. ihe structure of these is as follows :
What is isomerism? Explain with example.
Isomerism – Compounds with same molecular formula but different properties are called isomers of each other and this property is called isomerism.
Compounds with same molecular formula but different structures are called structural isomers. For example – if we make the carbon skeleton with four carbon atoms, then two different skeletons are possible.
Filling the remaining valencies with hydrogen the structures obtained are as follows –
Both these structures have the same molecular formula C4H10 which is butane. So this is the example of structural isomerism.
Explain the method of nomen-clature of carbon compounds in detail.
The names of compounds in a homologous series are based on the name of the basic carbon chain modified by a ‘prefix’, ‘phrase before’ or ‘suffix’ ‘phrase after’ indicating the nature of the functional group.
Following names are given on the basis of number of carbon atoms
1C = Meth
2C = Eth
3C = Prop
4C = But
5C = Pet
6C = Hex etc.
Naming a carbon compound can be done by the following Rules –
(1) Identify the number of carbon atoms in the compound. A compound having three carbon atoms would have the name propane and when four carbon atoms are present then have the name butane.
(2) In case a functional group is present, it is indicated in the name of the compound with either a prefix or a suffix (as given in Table).
(3) If the name of the functional group is to be given as a suffix, and the suffix of the functional group begins with a vowel a, e, i, o, u then the name of the carbon chain is modified by deleting the final ‘e’ and adding the appropriate suffix. For example, a three-carbon chain with a ketone group would be named in the following manner—
Propane – ‘e’ = propan + ‘one’ = propanone.
(4) If the carbon chain is unsaturated, then the final ‘ane’ in the name of the carbon chain is substituted by ‘ene’ or ‘yne’. For example, a three-carbon chain with a double bond is called propene and if it has a triple bond then it is called propyne.
Give the property of Ethanoic add and explain the following reactions of it
(b) Reaction with Base
(c) Reaction with sodium carbonate and sodium bicarbonate.
Properties of Ethanoic acid
Ethanoic acid is commonly called acetic acid and belongs to a group of acids called carboxylic acids.
5-8% solution of acetic acid in water is called vinegar is used as a preservative in pickles.
The melting point of pure ethanoic acid is 290 K and hence it often freezes during winter in cold climates. So this is known as glacial acetic acid.
Ethanoic acid is acidic in nature but unlike inorganic mineral acids like HCl, this is very weak acid.
Reactions of Ethanoic acid –
(a) Esterification reaction -Esters are mainly formed by reaction of an acid and an alcohol. Ethanoic acid reacts with, alcohol in presence of an acid catalyst to give an ester and this reaction is called esterification.
(b) Reaction with a base—Ethanoic acid reacts with a base such as sodium hydroxide to give a salt (sodium ethanoate or sodium acetate) and water.
CH3COOH + NaOH >CH3COONa + H2O
(c) Reaction with Sodium carbonate and Sodium hydrogen carbonate – Ethanoic acid reacts with Sodium carbonate and Sodium hydrogen carbonate to give rise a salt, carbondioxide and water. The salt produced in this reaction is called sodium acetate (sodium ethanoate).
Write the chemical properties of carbon compounds.
The main chemical properties of carbon compounds are as follows –
1. Combustion: Carbon, in all its allotropic forms, burns in oxygen to give carbon dioxide along with the release of heat and light. For example –
Saturated hydrocarbons bums with a clean flame while unsaturated carbon compounds bums with yellow flame with black smoke.
2. Oxidation—Carbon compounds can
be easily oxidised on combustion. In addition to complete oxidation there are some reactions in which alcohols are converted to carboxylic acids.
3. Addition Reaction: In this reaction unsaturated hydrocarbons add hydrogen in presence of catalysts such as palladium or nickel to give saturated hydrocarbons. This reaction is commonly used in the hydrogenation of vegetable oils using a nickel catalyst.
4. Substitution Reaction: Saturated hydrocarbons are fairly unreactive and inert in the presence of most reagents. However, in the presence of sunlight, chlorine reacts with hydrocarbons and the reaction is very fast. Chlorine replaces the hydrogen atoms one by one. It is called a substitution reaction because one type of atom or a group of atoms takes the place of another. A number of products are usually formed with the higher homologues of alkanes.
Write the properties of Ethanol. Explain the reactions of ethanol with –
(ii) Concentrated Sulphuric acid
(iii) Potassium permaganate
Physical Properties of Ethanol –
The physical properties of ethanol are as under –
Ethanol is a liquid at room temperature. The melting point and boiling point of it are 156K and 35IK successively.
Ethanol is commonly called alochol and it is active ingredient of all alcoholic drinks.
It is a good solvent so it is used in medicines such as tincture iodine, cough syrups and tonics.
Ethanol is also soluble in water in all proportions.
Consumption of small quantities of dilute ethanol causes drunkenness.
Chemical properties of Ethanol –
(1) Reaction with Sodium: Ethanol reacts with sodium and forms sodium ethoxide with the evolution of hydrogen gas.
(2) Reaction with concentrated sulphuric acid – Heating ethanol at 443 K with excess concentrated sulphuric acid results in the dehydration of ethanol to give ethene –
In this reaction concentrated sulphuric acid act as a dehydrating agent which removes water from ethanol.
(3) Reaction with Potassium Permangnate – Potassium permangnate oxidise the ethanol into Ethanoic acid
(a) Write the dehydration reaction of ethanol and write the name of dehydrating agent.
(b) Choose correct series for the following –
|(i) Ethane||(a) Unsaturated|
|(ii) Benzene||(b) Long chain saturated Hydrocarbon|
|(iii) Hexane||(c) Hydrocarbon|
|(iv) Methyl Alcohol||(d) Saturated Hydrocarbon carbon|
Ans. (a) Equation of dehydration of ethanol –
Here sulphuric acid (H2SO4) act as dehydrating agent.
(b) (i) Ethane (d)
(ii) Benzene (a)
(iii) Hexane (b)
(iv) Methyl Alcohol (c)
(a) Write die formula of Benzene.
(b) Draw the structure of benzene and write the number of triple bonds present in it.
(c) Among the following, which is ethane? Write the number of bonds present in it.
(a) Formula of benzene – C6H6
(b) Structure of benzene –
The number of triple bonds present in Benzene is zero.
The number of bonds present in ethane is 7.
(a) Write the formula of cyclohexane.
(b) Draw the structure of cyclohexane and write the number of bonds present in it.
(c) Which of the following in ethene ? Write the number of double bonds present in it.
(a) Cyclohexane – C6H12
(b) Structure of Cyclohexane –
There are 18 single bonds present in cyclohexane.
(c) Ethene – C2H4
The number of double bonds present in ethene is one.
(a) Define alkanes, alkenes and alkynes.
(b) Write the general formula for each category.
(c) Write names of four members from each category and give their formula.
(a) The compounds of hydrocarbon that are attached with only one bond between carbon atoms are called ‘alkanes’. Hydrocarbons that have one or more double bonds between carbon and carbon are called alkenes. Whereas hydrocarbons with one or more triple bonds between carbon- carbon are called alkynes.
(b) General formula –
Alkane = CnH2n+2
Alkyne =CnH2n-2 (n = 2, 3, 4)
(c) Members of alkane—
1. Ethane = C2H6
2. Propane = C3H8
3. Butane = C4H10
4. Pentane = C5H12
Members of alkene
1. Ethane = C2H4
2. Propene = C3H6
3. Butane = C4H8
4. Pentene = C5H10
Members of alkyne—
1. Ethyne = C2H2
2. Propyne = C3H4
3.Butyne = C4H6
4.Pentyne = C5H8
Give structural formula for the following carbon compounds and draw their electron dot structure.
(a) Methane and ethane
(b) Ethene and propene
(c) Ethyne and Propyne
(a) Methane = CH4
Structural formula –
Electron dot structure –
Ethane = C2H6
Structural formula –
Electron dot structure –
Ethene = C3H4
Structural formula –
Electron dot structure –
Propene = C3H6
Structural formula –
Electron dot structure –
(c) Ethyne = C2H2
Structural formula –
H – C ≡C – H
Electron dot structure –
Propyne = C3H4
Structural formula –
Electron dot structure –
Count the number of single, double and triple bonds in the following –
(b) Propanoic acid
Single bonds = 9
Double bonds = 3
Triple bonds =0
(b) Propanoic acid—CH3CH2COOH
Single bonds = 9
Double bonds = 1
Triple bonds = 0
Single bonds = 5
Double bonds = 0
Triple bonds = 1
Single bonds = 8
Double bonds = 0
Triple bonds = 0