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$\text{CH}_3-\text{CH}_2-\text{CH}_2-\text{CH}_2-\text{CH}_2-\text{CH}_3\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{Hexane}$
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$\ \ \ \ \ \ \ \ \ \ \ \ \text{CH}_3\\\ \ \ \ \ \ \ \ \ \ \ \ \ |\\\text{CH}_3-\text{CH}-\text{CH}_2-\text{CH}_2-\text{CH}_3\\\ \ \ \ \ \ \ \ 2-\text{Methylpentane}$
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$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{CH}_3\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |\\\text{CH}_3-\text{CH}_2-\text{CH}-\text{CH}_2-\text{CH}_3\\\ \ \ \ \ \ \ \ \ \ \ 3-\text{Methylpentane}$
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$\ \ \ \ \ \ \ \ \ \ \ \ \text{CH}_3\ \ \ \ \text{CH}_3\\\ \ \ \ \ \ \ \ \ \ \ \ \ |\ \ \ \ \ \ \ \ \ \ |\\\text{CH}_3-\text{CH}-\text{CH}-\text{CH}_3\\\ \ \ \ \ \ 2,3\text{ dimethylbutane}$
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$\ \ \ \ \ \ \ \ \ \ \ \ \text{CH}_3\\\ \ \ \ \ \ \ \ \ \ \ \ \ |\\\text{CH}_3-\text{C}-\text{CH}_2-\text{CH}_3\\\ \ \ \ \ \ \ \ \ \ \ \ \ |\\\ \ \ \ \ \ \ \ \ \ \ \ \text{CH}_3\\2,2\text{ dimethylbutane}$
Questions
Answer the questions.[Che-3M]
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Test yourself on this topic
6 questions · timed · auto-graded
Question 13 Marks
Write the structural formulae of all the isomers of hexane.
Answer
View full question & answer→Question 23 Marks
Unsaturated hydrocarbons contain multiple bonds between the two C-atoms and show addition reactions. Give the test to distinguish ethane from ethene.
Answer
View full question & answer→Distinction between ethane and ethene can be done with the help of bromine water test. Whereas ethene dicolourises the yellow colour of bromine water, ethane does not.
Question 33 Marks
Intake of small quantity of methanol can be lethal. Comment.
Answer
View full question & answer→When methanol is entered in our body, it is metabolized in the liver and form formaldehyde which further converted to formate. Formate is essential for survival because it acts as building block for many biomolecules but high levels of it can cause toxicity.
Formaldehyde also reacts with living cells and can cause coagulation of protoplasm. Excess of methanol in our body also affects the optic nerve and can cause blindness.
Formaldehyde also reacts with living cells and can cause coagulation of protoplasm. Excess of methanol in our body also affects the optic nerve and can cause blindness.
Question 43 Marks
How is ethene prepared from ethanol? Give the reaction involved in it.
Answer
View full question & answer→From ethanol: This method involves the slow oxidation of a dilute solution of ethanol (10-15 per cent) by oxygen present in air in the presence of an enzyme acetobactor.
$\text{CH}_3\text{CH}_2\text{OH}+\text{O}_2\xrightarrow{\ \ \text{Acetobactor}\ \ }\text{CH}_3\text{COOH}+\text{H}_2\text{O}\\\ \ \ \ \ \text{Ethanol}\ \ \ \ \ (\text{Air})\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{Ethanoic acid}\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (\text{as vinegar})$
The acid obtained is in the form of dilute solution called vinegar.
We have also studied under ethanol that it gets oxidized to ethanoic acid in the presence of dilute solution of alkaline KMnO4 or acidified K2Cr2O7.
Question 53 Marks
Ethene is formed when ethanol at 443K is heated with excess of concentrated sulphuric acid. What is the role of sulphuric acid in this reaction? Write the balanced chemical equation of this reaction.
Answer
View full question & answer→Conversion of ethanol to ethene is a dehydration reaction which occurs in the presence of excess of concentrated sulphuric acid. Here concentrated sulphuric acid acts as dehydrating agent and remove water molecule from ethanol to form ethene.
$\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{OH} \xrightarrow{\text { Hot Conc. } \mathrm{H}_2 \mathrm{SO}_4} \mathrm{CH}_2=\mathrm{CH}_2+\mathrm{H}_2 \mathrm{O}$
Hence concentrated sulphuric acid acts as a dehydrating agent as it removes water molecule.
$\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{OH} \xrightarrow{\text { Hot Conc. } \mathrm{H}_2 \mathrm{SO}_4} \mathrm{CH}_2=\mathrm{CH}_2+\mathrm{H}_2 \mathrm{O}$
Hence concentrated sulphuric acid acts as a dehydrating agent as it removes water molecule.
Question 63 Marks
Draw the electron dot structure of ethyne and also draw its structural formula.
Answer
View full question & answer→Ethyne is a hydrocarbon with molecular formula C2H2. Here two carbon atoms are bonded together by a triple covalent bond and one hydrogen atom is bonded with each carbon atom through a single covalent bond. Hence the electron dot structure of ethyne molecule can be representes as:
