Hydrocarbon Basics
What are alkanes made of?
Carbon and hydrogen atoms joined only by single bonds.
Are alkanes polar or nonpolar?
They are nonpolar.
What are the products of complete combustion of methane?
Carbon dioxide and water.
What kind of bonds do alkanes have?
Single covalent bonds.
What happens when bromine water is added to an alkene?
The orange-brown colour disappears.
Why are alkanes called saturated hydrocarbons?
Because every carbon atom holds as many hydrogen atoms as possible.
Why don’t alkanes dissolve in water?
Because they are nonpolar, and water is polar.
What happens when there isn’t enough oxygen for combustion?
Incomplete combustion occurs, producing carbon monoxide or soot.
How many hydrogen atoms are bonded to carbon in methane (CH₄)?
Four
What happens when bromine water is added to an alkane?
The orange-brown colour stays the same.
What is the general formula for alkanes?
CₙH₂ₙ₊₂
What makes alkanes less reactive than alkenes?
Their strong, nonpolar C–C and C–H bonds make them hard to break.
Write the balanced equation for complete combustion of methane.
CH₄ + 2O₂ → CO₂ + 2H₂O.
What type of bond do alkenes have that alkanes do not?
A carbon–carbon double bond (C=C).
What type of reaction links many ethene molecules together?
Addition polymerisation.
How are alkenes different from alkanes?
Alkenes have at least one carbon–carbon double bond, while alkanes have only single bonds.
How does the boiling point of alkanes change with size?
It increases as the molecules get larger.
What is cracking used for?
Breaking long-chain hydrocarbons into shorter, more useful ones.
In ethene (C₂H₄), how many hydrogen atoms are attached to each carbon?
2
Write the simplified equation for forming poly(ethene).
nCH₂=CH₂ → (–CH₂–CH₂–)ₙ.
What does the general formula CₙH₂ₙ tell you about alkenes?
It shows that alkenes have fewer hydrogen atoms than alkanes because of the double bond.
Why do alkenes take part in addition reactions but alkanes do not?
The double bond in alkenes can open up and form new bonds, while alkanes have only single bonds.
What are the products of cracking?
Both alkanes and alkenes.
Why is the double bond in alkenes important?
It makes them more reactive and allows them to form new compounds through addition reactions.
Why is poly(ethene) used to make bottles and bags?
Because it is strong, flexible, and resistant to chemicals.