Organic Chemistry: Alkanes and Fossil Fuels
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Questions and Answers

What is the specific heat capacity of the solution used in the heat of neutralization experiment?

  • 100 J Kg-1 K-1
  • 1000 J Kg-1 K-1
  • 2000 J Kg-1 K-1
  • 4080 J Kg-1 K-1 (correct)

    • The reaction between nitric acid and sodium hydroxide is endothermic.

    False

    What is the initial temperature of the solutions before mixing?

    15.6°C

    The equation used to calculate heat liberated is ____ = m c ∆T.

    <p>heat liberated</p> Signup and view all the answers

    Match the following components of the experiment with their descriptions:

    <p>HCl = Acid used in the reaction NaOH = Base used in the reaction m = Mass in kg of the solution ∆T = Temperature rise</p> Signup and view all the answers

    What is a characteristic of a homologous series?

    <p>Members differ from each other by a (CH2) unit.</p> Signup and view all the answers

    Structural isomers have different molecular formulas.

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

    What is the systematic name of the compound with the structural formula 2,3-dimethylpentane?

    <p>2,3-dimethylpentane</p> Signup and view all the answers

    The general formula for alkenes is CnH _____ .

    <p>2n</p> Signup and view all the answers

    Match the following alkenes to their formulas:

    <p>Ethene = C2H4 Propene = C3H6 Butene = C4H8</p> Signup and view all the answers

    Which of the following compounds is unsaturated?

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

    In alkanes, if two identical groups are present, the prefix ‘di-‘ is used.

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

    What is the main reason why structural isomers differ from each other?

    <p>Different structural arrangements</p> Signup and view all the answers

    What is the main color change observed when bromine water is added to certain substances?

    <p>Red to colourless</p> Signup and view all the answers

    Benzene is a reactive compound despite being unsaturated.

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

    What structure is characteristic of aromatic compounds?

    <p>Benzene ring</p> Signup and view all the answers

    Benzene is highly toxic and __________.

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

    Match the following fractions from crude oil with their corresponding uses:

    <p>Methane = Fuel for heating Ethane = Feedstock for ethylene production Propane = Fuel for cooking Butane = Lighter fuel</p> Signup and view all the answers

    During fractional distillation, where are larger molecules typically collected in the column?

    <p>Near the bottom</p> Signup and view all the answers

    Crude oil is already a useful material when extracted from the ground.

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

    What process involves converting straight-chain alkanes into their isomers using heat and a catalyst?

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

    Catalytic cracking always produces long-chain hydrocarbons.

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

    In fractional distillation, substances are separated into groups called __________.

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

    What is the octane number of 2-methylbutane?

    <p>93</p> Signup and view all the answers

    Hydrogen gas is produced through the steam reforming of natural gas by reacting methane with ______ in the presence of a catalyst.

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

    Which of the following gases are commonly referred to as LPG?

    <p>Propane and Butane</p> Signup and view all the answers

    Match the following reactions with their definitions:

    <p>Exothermic Reaction = Produces heat Endothermic Reaction = Takes in heat Heat of Reaction = Heat change during a reaction Thermochemistry = Study of heat changes in reactions</p> Signup and view all the answers

    Which of the following is NOT an oxygenate added to fuels to increase octane number?

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

    Octane number measures the tendency of a fuel to promote knocking in an engine.

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

    What is the main use of kerosene?

    <p>Domestic heating fuel and fuel for aircraft</p> Signup and view all the answers

    Electrolysis of water is a cost-effective way to produce hydrogen.

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

    What is the primary product of hydrogenation of vegetable oils?

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

    Mercaptans are added to gas to give it an __________ smell.

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

    Match the following petroleum products with their primary usage:

    <p>Petrol = Motor fuel Naphtha = Source for medicine and plastics Diesel oil = Fuel in trucks and buses Bitumen = Road surfacing and roofing</p> Signup and view all the answers

    Which factor increases the octane number of a fuel?

    <p>Branched alkane chains</p> Signup and view all the answers

    Adding lead to petrol helped to reduce engine knocking.

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

    What are the two reference hydrocarbons for measuring octane number?

    <p>2,2,4-trimethylpentane and Heptane</p> Signup and view all the answers

    What is the heat of neutralization for 1 mole of HNO3 neutralized?

    <p>55.488 kJ</p> Signup and view all the answers

    The heat of formation of water is +285.8 kJ mol-1.

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

    State Hess's Law in your own words.

    <p>Hess's Law states that the total heat change of a reaction is the same regardless of the number of stages taken to complete the reaction.</p> Signup and view all the answers

    The heat of formation represents the heat change when one mole of a compound is formed from its elements in their ________ states.

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

    Match the following equations to their corresponding heat changes:

    <p>C(s) + O2(g) → CO2(g) = -393 kJ mol-1 H2(g) + ½ O2(g) → H2O = -286 kJ mol-1 CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) = -879 kJ mol-1</p> Signup and view all the answers

    How much heat is liberated when 0.2 kg of a solution is heated, resulting in a temperature rise of 6.8°C, given a specific heat capacity of 4080 J kg-1 K-1?

    <p>5548.8 joules</p> Signup and view all the answers

    According to Hess's Law, the heat changes in separate stages can be ignored when determining the total heat change of a reaction.

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

    Calculate the number of moles of HNO3 neutralized if the volume is 100 mL.

    <p>0.1 moles</p> Signup and view all the answers

    Study Notes

    Organic Chemistry

    • Organic chemistry is the study of carbon compounds.
    • Carbon forms stable rings and chains of its atoms, and almost all organic compounds are covalent.
    • Hydrocarbons are compounds that contain only carbon and hydrogen.
    • Common sources of hydrocarbons are coal, natural gas, and petroleum.

    Fossil Fuels

    • Fossil fuels are fuels that were formed from the remains of plants and animals millions of years ago.

    Alkanes

    • Alkanes are a family of saturated hydrocarbons where all atoms are linked by single bonds.
    • Saturated compounds have only single bonds between atoms in the molecule.
    • All alkanes end in 'ane'.
    • The general formula for alkanes is CnH2n+2.
      • The first four members are gases.
      • The next 12 members are liquids.
      • Higher members are waxy solids.
    • Almost all alkanes are insoluble in water due to non-polar properties.
    • Alkanes are soluble in non-polar solvents.

    Homologous Series

    • A homologous series is a series of compounds with similar chemical properties and physical properties, with a gradation.
    • Each member differs from the previous one by a (CH2) unit.

    Isomers

    • Structural isomers are compounds with the same molecular formula but different structural formulas.

    Naming of Alkanes

    • Organic compounds are named according to the International Union of Pure and Applied Chemistry (IUPAC) rules.
    • Side chains are called alkyl groups (methyl - CH3, ethyl - C2H5).
    • Prefixes like "di-" indicate two identical groups.

    Alkenes

    • Alkenes are a homologous series of hydrocarbons containing one or more carbon-carbon double bonds.
    • Alkenes are unsaturated compounds.
    • The general formula for alkenes is CnH2n.

    Properties of Alkanes and Alkenes

    • Alkanes and alkenes have different solubilities in water and different boiling points based on the molecular size and shape.

    Aromatic Hydrocarbons

    • Aromatic compounds contain a benzene ring structure.
    • Benzene is a highly toxic and carcinogenic compound.

    Crude Oil and Fractional Distillation

    • Crude oil is a thick black liquid with an unpleasant smell, containing various fractions.
    • Fractional distillation is a process used to separate crude oil into its fractions based on boiling points.
    • Different fractions of crude oil have various uses.

    Octane Number

    • The octane number of a fuel is a measure of its resistance to knocking.
    • Knock is premature ignition of the fuel-air mixture.
    • Higher octane numbers mean better fuel.
    • Several factors influence an octane number: the length of carbons, the branching of carbons, and the presence of cyclic compounds.

    Making Petrol

    • Methods like isomerization and catalytic cracking. are applied to enhance the octane number of various fuels.
    • Octane numbers are related to these different types of hydrocarbon compounds.

    Hydrogen

    • Hydrogen is produced by steam reforming and electrolysis of water.
    • Hydrogen has a variety of industrial uses.
    • Hydrogen is a problematic fuel due to storage and transport concerns.

    Thermochemistry

    • Exothermic reactions release heat.
    • Endothermic reactions absorb heat.
    • Heat of reaction is the heat change when specific amounts of reactants react.
    • Heat of combustion is the heat change when one mole of a substance is completely burned in excess oxygen.

    Bond Energy

    • Bond energy is the average energy required to break one mole of a particular covalent bond.
    • Bond breaking requires energy, while bond forming releases energy.

    Mandatory Experiments

    • Experiments are described about preparing and examining the properties of ethene, and determining the heat of neutralisation of hydrochloric acid.

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    Description

    Explore the fascinating world of organic chemistry, focusing on carbon compounds, hydrocarbons, and alkanes. This quiz covers the properties of saturated hydrocarbons and their significance in fossil fuels. Test your knowledge on the structure and behavior of these essential organic molecules.

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