Explain why fluoroalkanes are more difficult to react with OH−ions than are bromoalkanes.

Fluoroalkanes are more difficult to react with OH- ions than bromoalkanes due to several reasons:

1. Bond Strength: Fluorine atoms form stronger bonds with carbon atoms than bromine atoms do. This is because fluorine is more electronegative than bromine, which means it attracts electrons more strongly. This results in a stronger bond that is harder to break, making fluoroalkanes less reactive.

2. Bond Length: The bond length between carbon and fluorine atoms is shorter than that between carbon and bromine atoms. Shorter bonds are generally stronger and more difficult to break, which makes fluoroalkanes less reactive.

3. Polarizability: Bromine atoms are larger and more polarizable than fluorine atoms. This means that they can distort their electron cloud more easily to initiate a reaction with the OH- ion. Fluorine's smaller size and lower polarizability make it less able to do this, which makes fluoroalkanes less reactive.

4. Steric Hindrance: Fluorine atoms are smaller than bromine atoms, which means they cause less steric hindrance. Steric hindrance is the effect of a molecule being physically blocked from reacting because of the size of the atoms or groups of atoms involved in the reaction. In the case of fluoroalkanes, the smaller fluorine atoms allow for less space for the OH- ions to approach and react, making the reaction more difficult.

In conclusion, the stronger bond strength, shorter bond length, lower polarizability, and less steric hindrance of fluoroalkanes compared to bromoalkanes make them more difficult to react with OH- ions.