properties of hydrocarbons

What factors affect the properties of hydrocarbons?

The length of the carbon chain and intermolecular forces between molecules.

How does chain length affect the boiling point of hydrocarbons?

Longer chains have higher boiling points because they have stronger intermolecular forces.

How does chain length affect viscosity?

Longer chains are more viscous (thicker) because the molecules stick together more.

How does chain length affect volatility?

Shorter chains are more volatile, meaning they evaporate more easily.

What is the trend in boiling points in the fractions from crude oil?

Boiling points increase as you go down the fractionating column (longer chains condense at higher temperatures).

What is the flammability of longer-chain hydrocarbons?

Longer chains are less flammable and harder to ignite.

What is the viscosity of shorter-chain hydrocarbons?

Shorter chains are less viscous (runny).

Why are shorter hydrocarbons better fuels?

They are more flammable and produce cleaner energy when burned.

What type of flame do short-chain hydrocarbons produce?

: A clean, blue flame during complete combustion.

What type of flame do long-chain hydrocarbons produce during incomplete combustion?

A smoky, yellow flame due to soot and unburnt carbon particles.

What is the relationship between boiling point and intermolecular forces?

Stronger intermolecular forces result in a higher boiling point.

Why do longer hydrocarbons burn less cleanly?

They require more oxygen for complete combustion, and incomplete combustion often occurs.

What happens to hydrocarbons with very short chains at room temperature?

They exist as gases because of their low boiling points.

What state are medium-chain hydrocarbons typically found in?

Liquids, such as petrol and kerosene.

What state are very long-chain hydrocarbons typically found in?

Solids or very thick liquids, like bitumen.

Why are longer hydrocarbons harder to ignite?

They have lower volatility and require more energy to vaporize and combust.

What is the relationship between volatility and chain length?

Volatility decreases as chain length increases.

What property makes short-chain hydrocarbons ideal for camping gas?

Their high volatility and flammability.

Why are long-chain hydrocarbons used in lubricants?

Their high viscosity makes them effective at reducing friction between moving parts.

Which fraction of hydrocarbons is most viscous: petrol, diesel, or bitumen?

Bitumen, because it contains the longest chains.

Which hydrocarbons are most likely to be gases at room temperature?

Short-chain hydrocarbons like methane, ethane, and propane.