Hydrocarbons Flashcards
(30 cards)
How is crude oil made?
Finite resource found in rocks, made by plankton that was buried in mud
What is the formula for alkanes?
Cn H2n+2
What are the first four alkanes?
Methane, ethane, propane, butane
Monkeys eat peanut butter
What is fractional distillation of crude oil?
- Crude oil is heated so most of it turns into gas, the gas enters a fractionating column
- The column is hot at the bottom cold at the top
- The longer hydrocarbons have higher melting points so they are collected at the bottom of the column
- The short hydrocarbons have lower melting points so they are collected at the top of the column
What does each fraction contain?
similar number of carbon atoms so they have similar boiling points
Properties of short chain hydrocarbons?
Short: Less viscous More flammable Lower boiling point Lighter colour
What is the word equation for complete combustion of a hydrocarbon?
Hydrocarbon + oxygen —> carbon dioxide + water
What is cracking?
Breaking down hydrocarbons to produce smaller and more useful molecules, alkane into an alkene
What is catalytic cracking?
Mineral wool is soaked in liquid paraffin in a test tube with porcelain chips and is heated. A smaller molecule is produced (alkene)
Conditions
High temperature
Slight pressure
Presence of a catalyst (obviously)
What is the formula for alkenes?
CnH2n
Properties of alkenes?
Double bond between the carbons, unsaturated
What are the conditions for steam cracking?
High temperatures
High pressure
What are the first four alkenes?
Ethene, propene, butene, pentene
What happens when alkenes are burnt in air, why?
Produce a yellow and smokier flame because of incomplete combustion and release less energy compared to alkanes
What is the functional group of alcohols?
-OH
What are the first four alcohols?
Methanol, ethanol, propanol, butanol
What happens when an alcohol reacts with a metal (e.g. sodium)?
Alcohol + metal —> salt + Hydrogen
What happens when an alkene reacts with hydrogen, halogens and steam?
Hydrogen - nickel catalyst at 60 degrees, an alkane is formed
Halogen, halogen is add
Water - Higher temperature, pressure, concentrated phosphoric acid and a catalyst. An alcohol is made (reversible reaction)
How do alcohols react when burnt, with sodium and an oxidising agent?
Combustion - react with oxygen to give carbon dioxide and water
Sodium - Salt + Hydrogen gas
Oxidising agent (chemical or microbes in the air) forms ethanoic acid
What is the functional group for carboxylic acids?
-COOH
What are the first four carboxylic acids?
Methanoic acid, ethanoic acid, propanoic acid, butanoic acid
What happens when carboxylic acids react with carbonates?
Carbon dioxide produced
What happens when carboxylic acids react with alcohols?
ester + water
What is addition polymerisation?
Alkenes are used to make polymers.
When the polymer is made there is no C=C double bond because each monomer needs to bond to the two other monomers on either side to make the polymer.
