Fossil Fuels, Hydrocarbons, and Polymers

Comprehensive practice flashcards covering fossil fuels, alkane and alkene structures, naming conventions, combustion reactions, fractional distillation, cracking, and addition polymerisation.

What are fossil fuels, and how were they formed?

Fossil fuels are a source of energy formed from ancient organic matter over millions of years through heat and pressure.

What are the three primary fossil fuels?

Coal, petroleum (crude oil), and natural gas.

What gas predominantly composes natural gas?

Natural gas is predominantly composed of methane ($CH_4$).

What is the definition of a hydrocarbon?

A compound that contains only hydrogen and carbon atoms.

What are alkanes, and what is their general formula?

Alkanes are saturated hydrocarbons containing only single carbon-carbon bonds, with the general formula $C_nH_{2n+2}$, where $n$ is the number of carbon atoms.

What are alkenes, and what is the general formula for open-chain alkenes with one double bond?

Alkenes are unsaturated hydrocarbons characterized by the presence of at least one carbon-carbon double bond, with the general formula $C_nH_{2n}$.

What prefixes indicate 1 to 4 carbon atoms when naming hydrocarbons?

1 carbon is Meth-, 2 carbons is Eth-, 3 carbons is Prop-, and 4 carbons is But-.

What prefixes indicate 5 to 10 carbon atoms when naming hydrocarbons?

5 carbons: Pent-, 6 carbons: Hex-, 7 carbons: Hept-, 8 carbons: Oct-, 9 carbons: Non-, and 10 carbons: Dec-.

What suffixes are used to denote alkanes and alkenes?

For alkanes, the suffix is -ane; for alkenes, the suffix is -ene.

What are the chemical formula and structure of ethane and ethene?

Ethane (alkane, 2 carbons) is $C_2H_6$ with the structure $CH_3 - CH_3$. Ethene (alkene, 2 carbons) is $C_2H_4$ with the structure $CH_2 = CH_2$.

What are the chemical formula and structure of propane and propene?

Propane (alkane, 3 carbons) is $C_3H_8$ with the structure $CH_3 - CH_2 - CH_3$. Propene (alkene, 3 carbons) is $C_3H_6$ with the structure $CH_2 = CH - CH_3$.

How is the chemical process of combustion defined?

Combustion is a chemical process that involves the rapid reaction between a substance with an oxidant, usually oxygen, to produce heat and light.

What conditions lead to complete combustion, and what are its products?

Complete combustion occurs when there is a plentiful supply of oxygen, producing carbon dioxide ($CO_2$) and water ($H_2O$).

What is the balanced equation for the complete combustion of methane?

$$CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O$$

What causes incomplete combustion, and what substances can be produced?

Incomplete combustion occurs when the oxygen supply is limited. Products can include carbon monoxide ($CO$), carbon (soot, $C$), and water ($H_2O$), in addition to carbon dioxide.

What are the balanced equations for the incomplete combustion of methane producing carbon monoxide and carbon (soot)?

Carbon monoxide production: $2CH_4 + 3O_2 \rightarrow 2CO + 4H_2O$. Carbon (soot) production: $CH_4 + O_2 \rightarrow C + 2H_2O$.

How does fractional distillation separate petroleum into fractions?

Petroleum is separated based on boiling points, with each fraction containing hydrocarbons with a similar range of boiling points and molecular sizes.

What are the main uses of refinery gas, gasoline (petrol), and naphtha?

Refinery gas is used as bottled gas for heating and cooking; gasoline (petrol) is fuel for cars; naphtha is a feedstock for the petrochemical industry used in making chemicals.

What are the main uses of diesel/gas oil and bitumen?

Diesel/gas oil is used as fuel for diesel engines, and bitumen is used for road surfaces.

What is cracking, and what substances does it produce?

Cracking breaks down long-chain, less useful hydrocarbons into shorter, more valuable molecules, often producing smaller alkanes, alkenes, and sometimes hydrogen.

What conditions are required for catalytic cracking versus thermal cracking?

Catalytic cracking requires high temperature and a catalyst, whereas thermal cracking requires very high temperature without a catalyst.

What are the two primary purposes of cracking?

To produce more useful short-chain fuels and to generate alkenes, which are important for the production of polymers.

What is the difference between a monomer and a polymer?

A monomer is a small molecule that can be joined with other monomers to form a polymer, while a polymer is a large molecule (macromolecule) composed of many repeating monomer units.

What chemical change occurs during addition polymerisation?

Many alkene monomers join together as the carbon-carbon double bond in each monomer breaks, allowing the monomers to link together to form a long chain.

What is the balanced equation and repeating unit for the polymerisation of ethene to poly(ethene)?

The reaction is $n(CH_2 = CH_2) \rightarrow [-CH_2 - CH_2-]_n$, where the repeating unit is $-CH_2 - CH_2-$.