What are the products of the complete combustion of alkanes?
Carbon dioxide (CO₂) and water (H₂O).
What are the possible products of the incomplete combustion of alkanes?
Carbon monoxide (CO), carbon (C/soot), and water (H₂O).
What is the condition required for the substitution reaction of alkanes with halogens?
Ultraviolet (UV) light or sunlight.
What is the functional group present in alkenes?
A carbon-carbon double bond (C=C).
Why do alkenes burn with a more smoky flame compared to alkanes?
Alkenes have a higher carbon-to-hydrogen ratio, leading to incomplete combustion and more soot production.
What type of reaction is characteristic of alkenes?
Addition reactions.
What catalyst is required for the hydrogenation of alkenes?
A nickel catalyst at 180°C.
What happens when ethene reacts with bromine water?
Ethene reacts with bromine water to form 1,2-dibromoethane, decolorizing the bromine water from brown to colorless.
What are the conditions needed for the hydration of ethene?
Steam, phosphoric acid catalyst, 300°C, and 60 atm pressure.
What is polymerization?
A reaction where small alkene molecules (monomers) join together to form long-chain molecules (polymers).
What is the general formula for alcohols?
CₙH₂ₙ₊₁OH
What are the products of the complete combustion of ethanol?
Carbon dioxide (CO₂) and water (H₂O).
What happens when ethanol is oxidized using acidified potassium dichromate(VI)?
Ethanol is oxidized to ethanoic acid (CH₃COOH), turning the dichromate solution from orange to green.
What is esterification?
The reaction between an alcohol and a carboxylic acid to form an ester and water in the presence of a concentrated acid catalyst.
What process converts alkanes to alkenes?
Cracking.
What type of reaction converts alcohols into alkenes?
Dehydration.
What type of reaction converts alcohols to carboxylic acids?
Oxidation.
What is the functional group in carboxylic acids?
Carboxyl (-COOH).
What is the reaction between carboxylic acids and alcohols called?
Esterification.
Explanation Questions
Why are alkanes considered saturated hydrocarbons?
Alkanes are considered saturated hydrocarbons because they contain only single covalent bonds between carbon atoms, meaning they cannot accommodate additional atoms without breaking a bond.
Why are alkenes more reactive than alkanes?
Alkenes are more reactive because they contain a carbon-carbon double bond, which has a high electron density and can easily participate in addition reactions.
Why does bromine water decolorize in the presence of alkenes but not alkanes?
Alkenes undergo an addition reaction with bromine, breaking the double bond and forming a colorless dibromo compound, whereas alkanes do not react.
Why is carbon monoxide considered a toxic gas?
Carbon monoxide binds to hemoglobin in the blood more strongly than oxygen, reducing oxygen transport and leading to suffocation.
What is the role of a catalyst in the hydrogenation of alkenes?
A nickel catalyst provides an active surface for the reaction, lowering the activation energy and allowing hydrogen to add across the double bond.
Why do alcohols burn with a blue flame in complete combustion?
Alcohols contain oxygen within their molecular structure, which helps them burn completely, producing only carbon dioxide (CO₂) and water (H₂O).
Why is polymerization of alkenes useful in industry?
Polymerization of alkenes produces useful materials like polyethylene and polypropylene, which are used in plastics, packaging, and textiles.
Why do alcohols undergo dehydration in the presence of sulfuric acid?
Sulfuric acid acts as a dehydrating agent, removing a water molecule from alcohols to form alkenes.
Why do carboxylic acids react with alcohols to form esters?
Carboxylic acids react with alcohols in the presence of an acid catalyst to form esters, which are used in fragrances and food flavorings.
Why do carboxylic acids react with metal carbonates to produce carbon dioxide gas?
Carboxylic acids react with metal carbonates because they are weak acids. When they react, they produce a salt, water, and carbon dioxide gas, which causes effervescence (bubbling). This reaction is a common test for acids.