Organic chemistry Flashcards
(51 cards)
What are organic compounds?
Any carbon compound except for the very simplest (carbon dioxide, carbon monoxide, the carbonates and the hydrogencarbonates)
What are hydrocarbons?
Compounds that only contain hydrogen and carbon atoms.
What is an empirical formula?
The simplest whole number ratio of the atoms in a compound.
What is a molecular formula?
It counts the actual number of each type of atom present in a molecule.
What is a homologous series?
- A series of compounds with similar chemical properties because they have the same functional group.
- Each member differs from the next one by one CH₂.
What is the general formula of alkanes?
CₙH₂ₙ₊₂
What is a functional group?
An atom or a group of atoms that determine the chemical properties of a compound.
What is a structural formula?
Shows how the atoms in a molecule are joined together.
What is a displayed formula?
- It shows all the bonds in the compound as individual lines.
- Each line represents a pair of shared electrons in a covalent bond.
What are alkanes?
A homologous series of similar hydrocarbons in which all the carbons are joined to each other with single covalent bonds.
What are alkenes?
A homologous series of hydrocarbons which contain a carbon=carbon double bond.
What are structural isomers?
Compounds with the same molecular formula but different structural formulae.
What are alcohols?
A homologous series of compounds which all contain an OH functional group attached to a hydrocarbon chain.
What happens when hydrocarbons combust in excess oxygen?
It gives rise to carbon dioxide and water, together with the release of a large amount of heat energy.
What is a substitution reaction?
When an atom or group of atoms is replaced by a different atom or group of atoms.
What is an addition reaction?
A chemical reaction in which one molecule adds to another without taking anything away, to form a single product.
What is the origin of crude oil?
- Millions of years ago, plants and animals living in the sea died and fell to the bottom
- Layers of sediment formed on top of them and their shells and skeletons formed limestone.
- The soft tissue was gradually changed by heat and high pressure into crude oil.
- Crude oil is a finite, non-renewable resource.
What is crude oil a mixture of?
Hydrocarbons.
What physical properties change when the number of carbon atoms in hydrocarbon molecules increases?
- Boiling point increases (Large molecules are attracted to each other more strongly than smaller ones. More energy is needed to break these stronger intermolecular forces of attraction).
- The liquids become less volatile (same reason as boiling point).
- The liquids become more viscous.(Because of the stronger forces of attraction between molecules).
- The liquids become darker in colour.
- They do not burn as easily.
What does volatile mean?
A substance that evaporates easily.
What does viscous mean?
A liquid that is resistant to flow.
What do fractions of crude oil contain?
Mixtures which each contain a narrow range of sizes of hydrocarbons with similar boiling points.
What process is used to separate crude oil into fractions?
Fractional distillation.
Describe the process of fractional distillation?
- Crude oil is heated until it boils and the vapours pass into a fractionating column (which is cooler at the top and hotter at the bottom).
- How far up the column a particular hydrocarbon moves depends on its boiling point.
- When the temperature of the column falls to the boiling point of the hydrocarbon, the hydrocarbon condenses and can be removed.
