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Organic Chemistry
Quick questions on Fuels and alkanes explained: O-Level Chemistry
8short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is the alkanes as a homologous series?Show answer
The alkanes are a homologous series: a family of compounds with the same general formula and similar chemical properties, where each member differs from the next by . The alkane general formula is:
What are saturated hydrocarbons?Show answer
The alkanes are saturated: they contain only single carbon-to-carbon bonds, so each carbon is bonded to as many hydrogen atoms as possible. Because the single bonds are strong and the molecules are otherwise unreactive, alkanes are fairly unreactive apart from burning. (This contrasts with the alkenes, which are unsaturated.)
What is complete combustion?Show answer
When an alkane burns in a plentiful supply of oxygen, it undergoes complete combustion to carbon dioxide and water, releasing a lot of heat (an exothermic reaction). For methane:
What is incomplete combustion?Show answer
When there is a limited supply of oxygen, combustion is incomplete, producing carbon monoxide () and (or) carbon (soot), along with water. Incomplete combustion is dangerous and undesirable because:
What are unbalanced combustion equations?Show answer
Balance carbon, then hydrogen, then oxygen last.
What is q1?Show answer
State the general formula of the alkanes. [1 mark]
What is q2?Show answer
Write the balanced equation for the complete combustion of ethane, . [2 marks]
What is q3?Show answer
Explain why incomplete combustion of a fuel is dangerous. [2 marks]