Chemistry CCEA AS Level 2.5 (Halogenoalkanes)

What is a saturated compound?

A compound in which all of the bonds between carbon atoms are single bonds

What molecules do halogenoalkanes contain?

Carbon, Hydrogen and one or more halogen atoms

Why are the molecules in a halogenoalkane polarised?

There is a large electronegativity difference between halogens and carbon

What influences the strength of intermolecular forces of attraction in a halogenoalkane?

Molar mass and polarity

What intermolecular forces of attraction are found in a halogenoalkane?

Permanent dipole-permanent dipole attraction and van der Waals

Why do intermolecular forces become stronger down the homologous series?

Increase in molecular mass and size

Why does the boiling point of halogenoalkanes increase down the homologous series?

Increase in van der Waals forces with increase of molar mass

Why does boiling point decrease with branching?

The molecule becomes more spherical and there are less van der Waals forces between the separate molecules

What is organic synthesis?

The process of making pure organic compounds from the starting materials

What is reflux?

The repeated boiling and condensing of a reaction mixture

What is a nucleophile?

An ion or molecule (with a lone pair of electrons) that attacks regions of low electron density

What is a hydrolysis reaction?

The breaking up of molecules by reaction with water

How is hydrolysis carried out?

Heating under reflux

What do halogenoalkanes form with an aqueous alkali?

The corresponding alcohol

What do halogenoalkanes form with ammonia?

The corresponding amine

What do halogenoalkanes form with potassium cyanide?

The corresponding nitrile

What is the significance of the hydrolysis reaction?

It extends the carbon chain by one carbon

What is the reaction of primary halogenoalkanes known as?

An SN2 reaction

What is the reaction of a tertiary halogenoalkane known as?

An SN1 reaction

How does bond enthalpy affect rate of hydrolysis?

The weaker the bond (the lower the bond enthalpy) the faster the hydrolysis reaction will occur

What is an elimination reaction?

Removal of a small molecule from a larger one

Why were CFCs originally used in aerosols?

They have a low reactivity, they're volatile and they're non-toxic

Why are CFCs nonreactive and volatile?

They have strong covalent C-H bonds and no double/triple bonds as well as only weak intermolecular forces of attraction which are easily broken

Why were CFCs banned?

They cause damage to the ozone layer

How do CFC's damage the ozone layer?

Their lack of reactivity allows them to reach the stratosphere without being broken down. They are then broken down by UV radiation, causing them to form chlorine free radicles which attack the O3 molecules, converting them to O2, reducing the ozone layer