Alkanes: Properties and Intermolecular Forces

This video tutorial covers the structure and properties of alkanes, focusing on their saturated hydrocarbon nature and the formation of sigma bonds. It explains why alkanes are non-polar and insoluble in water, and discusses their general unreactivity. The video also explores the relationship between the carbon chain length and boiling points, highlighting how longer chains and greater surface areas increase London dispersion forces, leading to higher boiling points. Additionally, it examines how branching in alkanes affects boiling points by reducing the strength of London forces.

What is the general formula for alkanes?

• CnH2n-2

• CnH2n+1

• CnH2n+2

• CnH2n

What type of bond is primarily found in alkanes?

• Sigma bond

• Hydrogen bond

• Pi bond

• Ionic bond

Why are alkanes insoluble in water?

• They are polar molecules.

• They can form hydrogen bonds.

• They are ionic compounds.

• They have no permanent dipoles.

What is a key reason for the unreactive nature of alkanes?

• Presence of pi bonds

• Weak intermolecular forces

• Strong covalent bonds

• High electronegativity

How does the boiling point of alkanes change with increasing chain length?

• It remains constant.

• It fluctuates randomly.

• It decreases.

• It increases.

What type of intermolecular forces are present in alkanes?

• Hydrogen bonds

• Ionic bonds

• London dispersion forces

• Dipole-dipole interactions

Why do longer chain alkanes have higher boiling points?

• They are more polar.

• They have stronger London forces.

• They have a smaller surface area.

• They have fewer electrons.

What effect do branches have on the boiling point of alkanes?

• Increase the boiling point

• Decrease the boiling point

• No effect on boiling point

• Make them more reactive

Why do branched alkanes have lower boiling points than straight chain alkanes?

• They prevent molecules from getting close.

• They are more polar.

• They have a larger surface area.

• They have stronger London forces.

Which of the following alkanes would likely have the lowest boiling point?

• Decane

• Octane

• Hexane

• 2,3-dimethylbutane