Alcohols and Haloalkanes Overview
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Questions and Answers

What product is formed when CH​3​CH​2​OH reacts with HBr?

  • CH​3​CH​2​Br (correct)
  • CH​3​CH​2​I
  • P​I​3
  • H​2​O (correct)

    • What occurs during the dehydration of alcohols?

  • Removal of a water molecule (correct)
  • Production of ketones
  • Release of carbon dioxide
  • Formation of halides

    • What is the product when primary alcohols are oxidized using acidified potassium dichromate(VI)?

  • Aldehyde (correct)
  • Ketone
  • Alcohol
  • Carboxylic acid

    • What happens to potassium dichromate(VI) when it is used in the oxidation of alcohols?

    <p>It gets reduced</p> Signup and view all the answers

    Which of the following describes the bonds present in haloalkanes?

    <p>Polar bonds</p> Signup and view all the answers

    What compound is produced when an aldehyde is oxidized under reflux conditions?

    <p>Carboxylic acid</p> Signup and view all the answers

    During the oxidation of propan-2-ol with acidified potassium dichromate(VI), what is formed?

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

    What is the visible change observed when alcohols are oxidized with potassium dichromate(VI)?

    <p>Change from orange to green</p> Signup and view all the answers

    What is the range of the fingerprint region in an IR spectrum?

    <p>500-1500 cm⁻¹</p> Signup and view all the answers

    Which of the following gases contributes to global warming through infrared radiation absorption?

    <p>CO₂</p> Signup and view all the answers

    What does mass spectrometry primarily identify?

    <p>Different molecules and their relative molecular mass</p> Signup and view all the answers

    What happens during the ionisation step of TOF mass spectrometry?

    <p>Sample is vaporised and ionised</p> Signup and view all the answers

    In TOF mass spectrometry, what determines the radius of the path that ions take?

    <p>The charge and mass of the ion</p> Signup and view all the answers

    How is the relative abundance of each isotope determined in mass spectrometry?

    <p>By analyzing the current produced when ions hit the detector</p> Signup and view all the answers

    What is displayed in the spectra print-out produced by mass spectrometry?

    <p>The relative abundance of each isotope</p> Signup and view all the answers

    Which bond types are relevant for the absorption of IR radiation by atmospheric gases?

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

    What is a nucleophile defined as?

    <p>An electron pair donor</p> Signup and view all the answers

    Which of the following is a common nucleophile?

    <p>:OH</p> Signup and view all the answers

    What is the effect of increasing the Mr of the halogen in a haloalkane on the reaction rate?

    <p>It decreases bond enthalpy, making the bond easier to break.</p> Signup and view all the answers

    For which types of haloalkanes can nucleophilic substitution reactions occur?

    <p>Primary and secondary</p> Signup and view all the answers

    What environmental issue is associated with CFCs?

    <p>They catalyze the breakdown of the ozone layer.</p> Signup and view all the answers

    What is the first step in the radical mechanism for the breakdown of ozone?

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

    In the radical mechanism for ozone breakdown, what happens in Propagation 1?

    <p>Cl + O3 → ClO + O2</p> Signup and view all the answers

    What is the overall equation for the breakdown of ozone?

    <p>2O3 → 3O2</p> Signup and view all the answers

    What is the general formula for alcohols?

    <p>C_nH_{2n+1}OH</p> Signup and view all the answers

    Which type of alcohol has the hydroxyl group attached to a carbon bonded to two other carbons?

    <p>Secondary alcohol</p> Signup and view all the answers

    What happens when alcohols combust with oxygen?

    <p>They release energy and form carbon dioxide and water.</p> Signup and view all the answers

    What type of bond allows alcohols to be soluble in water?

    <p>Hydrogen bonds</p> Signup and view all the answers

    What is replaced by a halogen when alcohols react with halogenating agents?

    <p>Hydroxyl group (-OH)</p> Signup and view all the answers

    What indicates the presence of alcohol when reacting with PCl5?

    <p>Release of white steamy fumes</p> Signup and view all the answers

    Which of the following is true regarding the volatility of alcohols compared to alkanes?

    <p>Alcohols are less volatile than alkanes.</p> Signup and view all the answers

    In the context of alcohols, what does nucleophilic substitution involve?

    <p>Replacement of -OH with a halogen</p> Signup and view all the answers

    What is the primary purpose of using reflux apparatus in organic synthesis?

    <p>To continually heat the contents to drive reactions to completion</p> Signup and view all the answers

    How does distillation separate liquids?

    <p>According to their different boiling points</p> Signup and view all the answers

    What does the separating funnel primarily achieve?

    <p>Separating two liquids with different densities</p> Signup and view all the answers

    What occurs during the redistillation process?

    <p>Subsequent distillations are performed for improved purity</p> Signup and view all the answers

    What method is used to experimentally determine the boiling point of a compound?

    <p>Heating substance in a Thiele tube and observing condensation</p> Signup and view all the answers

    What indicates the purity of a substance when comparing boiling points?

    <p>Closeness to a known databook boiling point value</p> Signup and view all the answers

    What happens to vapors in a reflux apparatus?

    <p>They condense and return to the flask</p> Signup and view all the answers

    In boiling point determination, what is measured during the condensation process?

    <p>The temperature at which the liquid condenses</p> Signup and view all the answers

    What type of haloalkane has a halogen attached to a carbon that is at the end of the carbon chain?

    <p>Primary haloalkane</p> Signup and view all the answers

    Which halogen bond is considered the strongest in haloalkanes?

    <p>C-F bond</p> Signup and view all the answers

    In a nucleophilic substitution reaction of haloalkanes, what does the hydroxide ion act as?

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

    What is the order of reactivity for haloalkanes from least to most reactive based on bond strength?

    <p>Chloroalkanes &lt; Bromoalkanes &lt; Iodoalkanes</p> Signup and view all the answers

    What color precipitate is formed when silver nitrate reacts with chloride ions?

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

    When hydrolysis occurs with aqueous silver nitrate and ethanol, which product is formed along with halide ions?

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

    What happens to the bond enthalpy of haloalkanes as the molecular weight (Mr) of the halogen increases?

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

    Which reaction produces alkenes from haloalkanes?

    <p>Elimination with ethanolic potassium hydroxide</p> Signup and view all the answers

    Study Notes

    Alcohols, Haloalkanes, and Analysis

    • Alcohols:

      • Contain an -OH group.
      • General formula: CnH2n+1OH.
      • Can be primary (1°), secondary (2°), or tertiary (3°).
      • Are polar molecules due to electronegativity difference between carbon and oxygen.
      • Can hydrogen bond to water molecules, making them water-soluble.
      • Less volatile than alkanes due to stronger intermolecular forces (hydrogen bonds).
      • Can be produced via fermentation or hydration.
      • Named according to IUPAC rules, adding the suffix -ol.

    • Reactions of Alcohols:

      • Combustion: React with oxygen to produce carbon dioxide and water, releasing energy. Example: 2CH3OH + 3O2 → 2CO2 + 4H2O

    • Reactions with Halogenating Agents:

      • Alcohols react with halogenating agents (e.g., PCl3, concentrated H2SO4 + KBr) to form haloalkanes.
      • The -OH group is replaced by a halogen atom.
      • Can be used as a test via reaction with PCl3 that produces white fumes.
      • Reactions produce other products depending on which halogen-based compound is used.

    • Elimination Reactions:

      • Alkenes are produced by dehydration of alcohols (removal of water).
      • Heated with concentrated phosphoric acid.

    • Oxidation of Alcohols:

      • Primary alcohols can be oxidised to aldehydes, then to carboxylic acids.
      • Secondary alcohols can be oxidised to ketones.
      • Tertiary alcohols are not easily oxidised.
      • Oxidising agent: Acidified potassium dichromate(VI), visible colour change from orange to green occurs during the reaction.

    Haloalkanes

    • Structure and Properties:

      • Contain a halogen atom (F, Cl, Br, or I) bonded to a carbon atom.
      • Polar molecules due to the electronegativity difference between carbon and the halogen.
      • Reactivity varies based on the halogen (fluorine is most reactive, iodine is least).
      • Reactivity decreases going down the halogen group, as bond strength decreases.

    • Substitution Reactions:

      • React with aqueous alkali (e.g., NaOH) to form alcohols in a nucleophilic substitution reaction.
      • Hydroxide ion acts as the nucleophile.
      • React with ethanolic potassium hydroxide (KOH) to form alkenes via an elimination reaction.
      • Hydrolysed with silver nitrate in ethanol to produce silver halide precipitates.

    • Nucleophilic Substitution Mechanism:

      • Nucleophile attacks the carbon with a partial positive charge (δ+), and electrons are transferred to the halogen leaving group.
      • Mechanism varies based on whether the haloalkane is primary (1°), secondary (2°), or tertiary (3°).

    • Relative Reactivity of haloalkanes: Reactivity increases with larger molar mass of halogen (I>Br>Cl>F)

    Organic Synthesis

    • Synthetic Routes:

      • Steps to produce a specific organic compound from a starting material.
      • Consider reagents, reaction types, by-products, and safety.
      • Efficient choice leads to lower costs and better sustainability.

    • Multi-Stage Synthesis:

      • Involved multiple steps to produce a target molecule.
      • Reactant→Intermediate→Product.
      • Used for complex molecule synthesis.

    • Drying Agents:

      • Used to remove water from organic compounds during purificiation.
      • Example chemicals: magnesium sulfate, calcium chloride.

    Analytical Techniques

    • Infrared Spectroscopy (IR):

      • Used to identify functional groups by analysing infrared radiation absorbance.
      • Different functional groups absorb IR radiation at characteristic frequencies and produce unique spectral curves (fingerprints).
      • Indicates presence of specific bonds.

    • Mass Spectrometry:

      • Identifies compounds based on their mass-to-charge ratio (m/z).
      • Shows relative abundance of each isotope within the molecule.
      • Can determine the overall molecular mass of the molecule, and identify fragmentation patterns for determining structure.
      • Time of Flight (TOF) method: records the time ions take to reach a detector for generating a spectrum.

    • Combined Analytical Techniques: Used to help determine the structure of unknown organic compounds, e.g. Infrared spectroscopy & mass spectrometry.

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    OCR A Chemistry A-level Alcohols, Haloalkanes & Analysis Detailed Notes PDF

    Description

    This quiz covers the fundamental concepts of alcohols and haloalkanes, including their structures, properties, and reactions. Learn about the classification of alcohols as primary, secondary, or tertiary, and explore their reactions with halogenating agents. Test your understanding of these important organic compounds and their significance in chemistry.

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