Organic chemistry Flashcards
What are hydrocarbons?
Compounds that consist of carbon and hydrogen only
What is crude oil?
(dark, viscous liquid)
-A complicated mixture of many hydrocarbon molecules of different sizes and shapes
Why/ how is crude oil separated?
- In its raw state, crude oil is virtually useless
- But it can be refined to extract useful components
- Refined using the process fractional distillation
State the principles of fractional distillation and how it works?
- The crude oil is vaporised and passed into the bottom of a long column
- That is hot at the bottom and cool at the top
- The heavier a compound (the more carbons it has), the higher its boiling point
- That means that the heavier compounds leave the column first towards the bottom, where the temperature is the highest
- The really light compounds leave the column towards the top where the temperature is lower
How does the chain length of a hydrocarbon affect it’s boiling point?
- Heavier compounds
- With longer chains
- Make larger molecules
- Have greater intermolecular forces of attraction
- Require more energy to overcome
- Have higher boiling points
How does the chain length of a hydrocarbon affect it’s viscosity?
- Heavier compounds
- With longer chains
- Are more viscous
- As longer/ heavier chains are thicker in their liquid form
What is meant by the term “volatility”? How does the chain length of a hydrocarbon affect it’s volatility?
“The volatility of a compound is its tendency to evaporate at a given temperature”
- Heavier compounds
- With longer chains
- Are less volatile
How does the chain length of a hydrocarbon affect it’s ability to ignite?
Heavier compounds, with longer chains, do not ignite easily
Lighter more shorter chains, ignite more easily
What is catalytic cracking?
A second refinement process, that “cracks”/ passes the longer chain molecules from fractional distillation, over a heated catalyst that breaks them into even smaller chained alkanes/ alkenes
What is the molecular formula of a compound?
The formula that shows the actual no. of atoms in each element in one molecule of that compound
What is a (displayed/full) structural formula?
The formula that specifies/ shows how the atoms are arranged, including all the covalent bonds
What is a (condensed) structural formula?
The formula that specifies/ shows how the atoms are arranged, in a compact way (without showing the covalent bonds)
What is meant by the term “structural isomerism”?
Structural isomerism arises when it is possible to sequence the atoms in a molecular formula in more than 1 way
- have the SAME MOLECULAR formula
- but DIFFERENT STRUCTURAL formula
What is complete combustion?
When you burn a hydrocarbon [reacts with oxygen] “properly”, with enough/ excess oxygen and you form carbon dioxide and water, with a release of energy
How would you balance an equation showing COMPLETE combustion?
- The number of molecules of carbon dioxide formed will be given by the number of carbon atoms in the hydrocarbon
- The number of molecules of water formed will be half of the number of hydrogen atoms in the hydrocarbon
- All that remains is to balance the oxygen atoms
What is incomplete combustion?
When you burn a hydrocarbon [react with oxygen] with an insufficient supply of oxygen, producing carbon monoxide IN ADDITION TO carbon dioxide and water, with a release of energy
What is meant by the term “homologous series”?
a family of hydrocarbons with similar chemical properties who share the same general formula
What is a functional group?
Functional groups refer to specific atoms bonded in a certain arrangement that give a compound certain physical and chemical properties
What are alkanes?
- Simplest homologous series
- General formula CnH2n+2
- Saturated chains of carbon atoms
What is meant by the term saturated?
All the carbon-to-carbon bonds in the molecule are SINGLE bonds
What is the general formula for alkenes?
CnH2n
What is the difference between alkanes and alkenes?
Alkenes are unsaturated hydrocarbons:
-contain carbon and hydrogen atoms only, but there is at least one carbon-to-carbon bond in the molecule that is a double bond (C=C)
What are the rules to naming alkenes?
- The number that indicates the position of the double bond is the lower of the two possible numbers
- The number is inserted in the name after the prefix and before the suffix.
- Numbers are separated by “,” and words and numbers and separated with “-“
- If there is more than one double bond, the suffix -diene, -triene, and so on
- Each double bond must have a number to indicate its position
How do you test for alkenes/ unsaturation?
- Add bromine water/ (if testing a gas, bubble the gas into a solution of bromine water) to the solution you’re testing
- If an alkene is present, the bromine water changes from orange to colourless
