levo

Halogenoalkanes, Alcohols and Organic Analysis

Effect of Bond Enthalpy on Reaction Rate

  • 3 things to know
  • Papers 2 and 3

Overview

Why iodoalkanes hydrolyse fastest, and why bond enthalpy matters more than polarity here.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Evaluation

Why does the carbon-halogen bond enthalpy set the rate of substitution?

Key term

Why do halogenoalkanes with different halogens react at different rates with nucleophiles?

Key term

What is the trend in carbon-halogen bond enthalpies from C-F to C-I?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Why do halogenoalkanes with different halogens react at different rates with nucleophiles?

    Model answer

    The carbon-halogen bond must be broken during the reaction, and different carbon-halogen bonds have different bond enthalpies.

  2. 2

    What is the trend in carbon-halogen bond enthalpies from C-F to C-I?

    Model answer

    Bond enthalpy decreases from C-F to C-I (C-F is strongest, C-I is weakest).

  3. 3

    Which carbon-halogen bond is the strongest?

    Model answer

    The C-F bond.

  4. 4

    Which carbon-halogen bond is the weakest?

    Model answer

    The C-I bond.

  5. 5

    How does bond enthalpy relate to the ease of breaking a carbon-halogen bond?

    Model answer

    Weaker bonds (lower bond enthalpy) are easier to break, requiring less energy.

  6. 6

    Which halogenoalkane reacts fastest with aqueous hydroxide ions: fluoroalkane, chloroalkane, bromoalkane, or iodoalkane?

    Model answer

    Iodoalkane.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book
2Open book
3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Atomic Structure
Amount of Substance
Bonding
Energetics and Thermodynamics

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

A atom.
nitrogencarbonsulfur

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AOxidation is the loss of electrons.
BReduction is the gain of electrons.
CAn oxidising agent is an electron acceptor.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

The sum of all mole fractions equals 1.
TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Halogenoalkanes, Alcohols and Organic Analysis, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Or £46 a year, about £3.83 a month. Cancel anytime.