Cracking Hydrocarbons

What is cracking?

The thermal decomposition of long-chain hydrocarbons into smaller, more useful molecules.

Why is cracking used?

To produce shorter hydrocarbons and alkenes from less useful long-chain fractions.

What type of reaction is cracking?

Thermal decomposition.

What does thermal decomposition mean?

The breakdown of a substance by heating.

Why are long-chain hydrocarbons cracked?

Demand for short-chain fuels and alkenes is greater than their natural supply from crude oil.

What are the main products of cracking?

Shorter alkanes and alkenes.

Why are shorter alkanes useful?

They are more volatile and easier to ignite, making them useful fuels.

Why are alkenes useful?

They are used to manufacture polymers and other chemicals.

What bonds are broken during cracking?

Covalent bonds within long hydrocarbon molecules.

Why is cracking a chemical change?

New substances with different molecular structures are formed.

What is catalytic cracking?

Cracking hydrocarbon vapours using a hot catalyst.

What is steam cracking?

Cracking hydrocarbon vapours by mixing them with steam at a very high temperature.

Why are hydrocarbon vapours used in cracking?

They can be heated and brought into contact with a catalyst or steam.

Why is cracking important to the petrochemical industry?

It provides alkenes for manufacturing plastics and other useful products.

What is an example of a possible cracking equation?

C₁₀H₂₂ → C₈H₁₈ + C₂H₄.

Why must cracking equations be balanced?

The number of atoms of each element must be conserved.

Can cracking produce more than two molecules?

Yes, a long hydrocarbon may form several smaller molecules.

Why does cracking not produce only alkanes?

Breaking a long alkane into smaller hydrocarbons can produce unsaturated molecules containing C