Carbon/Organic Chemistry

Alkane general formula

CnH2n+2

What is an Alkane?

A saturated hydrocarbon (Single bonds only. All C atoms are bonded to 4 other atoms )

Alkene general formula

CnH2n

What is an Alkene?

An unsaturated hydrocarbons (not every C atom is bonded to 4 other atoms. They contain a double bond)

What is the type of bonding called?

Covalent bonding

How do atoms achieve a full valance shell?

the atoms share pairs of electrons to achieve a full valence shell

What is a melting point?

the temp at which substances change from a solid to a liquid

What is a boiling point?

the temp at which substances change from a liquid to a gas

What must happen for a substance to melt/boil?

The particles must vibrate or move fast enough to become free of a solid or a liquid

At room temp what state are Alkanes C1-4?

Gases

At room temp what state are Alkanes C5-8?

Liquids

At room temp what state are Alkenes C2 and C3?

Gases

At room temp what state are Alcohols C1 and C2?

Liquids

What is the melting and boiling point trend?

As the number of C atoms increases, the mass of the molecules increases and melting and boiling points increase. More energy is needed to seperate particles (melting) and/or for particles to escape the liquid state (boiling).

Extra on melting and boiling points trends.

As the size of the molecule increase so does the strength of the attractive forces between the molecules. More energy is required to overcome these weak attractive forces between molecules to allow a change in state.

What is an Alcohol?

NOT hydrocarbons as they contain oxygen.

Have an alcohol group O-H, sometimes simply written as OH.

Are Alkanes or Alkenes soluble in water?

Alkanes and Alkenes are all insoluble in water; Immiscible liquids do not mix, but seperate into two distinct layers when placed in the same container.

What two substances are soluble in water?

Methanol and ethanol are completely soluble in water.

What is crude oil?

A mixture of hydrocarbon molecules of different sizes.

How are the hydrocarbons separated?

Hydrocarbons of different molecular masses have different boiling points and are separated by fractional distillation; The molecular mass determines where on the tower the particular fraction is collected.

Where do larger hydrocarbons end up?

Larger, heavier hydrocarbons - more C atoms (with high boiling points) condense into liquids lower down the tower.

Where do smaller hydrocarbons end up?

Smaller, lighter hydrocarbons - less C atoms (with lower boiling points) rise up the tower and condense into a liquid at the lower temperatures near the top of the tower.

Where do smallest hydrocarbons end up?

The smallest hydrocarbons (C1-C4) remain as gases and leave the tower at the very top.

What are two examples of fractions and their uses.

Light distillates - fuel and kerosene

Residues - bitumen for roads or asphalt

What is a polymer made of?

A polymer is made from alkenes, ethene and propene

What is poly(ethene)?

Poly(ethene) is many small ethene molecules that are joined together to form long-chain molecules.

How is poly(ethene) formed?

The (covalent) double bond between each carbon atom in ethene is broken and single bonds formed between the carbon atoms, forming long carbon chains.

Is poly(ethene) strong?

Poly(ethene) is tough as it consists of many strong, long chain, molecules which overlap each other, to form sheets.

Poly(ethene) uses

Plastic bags, cling wrap and squeeze bottles

Why is poly(ethene) good for plastics?

Poly(ethene) is suitable for food containers as it has low chemical reactivity and can be heated and moulded into shapes.

What is combustion?

burning; an oxidation reaction

What is complete combustion?

Complete combustion in plentiful O2 supply, producing CO2 and H2O products; clean almost invisible flame. Sufficient oxygen present for all the carbon atoms to react with O2 to form CO2

What is incomplete combustion?

Incomplete combustion in limited O2, not enough oxygen present in the air for all of the carbon atoms to turn into carbon dioxide. Shown by a yellow flame, producing C (soot), CO and H2O as products.

Does complete or incomplete combustion produce more energy?

Complete combustion is a more efficient producer of energy than incomplete combustion.

Define Hydrocarbon

A compound of hydrogen and carbon