7. Organic Chemistry
No description yet. This curated deck is ready for daily study.
Card preview (24)
What is a hydrocarbon?
A fuel; a molecule that consists of hydrogen and carbon
What is crude oil?
A fuel made from remains of marine plants and animals to form sedimentary rock. When pressure and heat was added the rock was broken down to form crude oil and natural gas
What are many of the compounds in crude oil?
Hydrocarbons - mostly alkanes
What is an alkane?
Contains a single chains of carbon atoms with hydrogen atoms bonded along the side
What is the formula for alkanes?
CnH2n+2
What is the simplest alkane?
Methane
What are the four simplest alkanes?
Methane, ethane, propane and butane
What is a molecular formula?
Gives number of atoms of each element in a molecule
What is a structural formula?
Shows the atoms molecule by molecule
What is the displayed formula?
Shows how atoms are arranged and the bonds between them
What happens as the number of carbons in a molecule increases?
Boiling point increases because more energy is needed to break the intermolecular forces
Gases in fractional distillation which have the lowest boiling point also are…
The most volatile and flammable
What is viscosity?
The resistance of flow that a liquid has
What happens in fractional distillation as molecule size decreases in terms of colour?
Becomes lighter: black, yellow, transparent
Why are hydrocarbons cracked?
Long chains are not useful
What types of cracking are there?
Thermal and catalytic cracking
Why are fractions with large hydrocarbon molecules more viscous?
Longer chains are easily entangled. The amount of intermolecular force also affects viscosity
How is thermal cracking carried out?
Long hydrocarbon chains are vaporised, and placed under high pressure and temperatures (~750c) and thermal decomposition takes place - chains are split apart
How is catalytic cracking carried out?
Long hydrocarbon chains are vaporised and passed over a hot catalyst - heat to a high temperature (~500c). Chains cracked as thermal decomposition takes place
What is a disadvantage of thermal cracking?
There is not a lot of control over what products are formed
What is an advantage of catalytic cracking?
Longer chains are split to smaller chains - about 8-10 carbons in length
What does cracking hydrocarbons produce?
A mixture of alkanes and alkenes
Why are porcelain chips used in catalytic cracking in the lab?
As a catalyst - where thermal decomposition takes place
What are alkenes used to produce?
Polymers (plastics)