Cracking Flashcards

All 6 cards in this deck

What is cracking?

Breaking down larger, saturated hydrocarbon molecules (alkanes) into smaller, more useful ones, some of which are unsaturated (alkenes).

Why is cracking necessary?

The supply of the long-chain fractions (e.g. fuel oil) is greater than the demand, while demand for short-chain fractions such as petrol is greater than the supply.

What conditions are used for cracking alkanes?

A high temperature (heat) and a catalyst.

How do you find the missing molecule in a cracking equation?

e.g. $\mathrm{C_{10}H_{22} \rightarrow \text{?} + C_2H_4}$

1. Carbons must balance: $10 - 2 = 8$
2. Hydrogens must balance: $22 - 4 = 18$
3. Missing molecule is $\mathrm{C_8H_{18}}$.

True or false? All the products of cracking an alkane are alkanes.

False. Cracking produces smaller alkanes and at least one unsaturated alkene.

In cracking, what is meant by a saturated and an unsaturated hydrocarbon?

Saturated = only single carbon–carbon bonds (alkanes); unsaturated = contains at least one carbon–carbon double bond (alkenes).