Hydrocarbons + Carboxylic Acids Flashcards
What are most hydrocarbons?
Alkanes
What is the structure of alkanes?
Carbon atoms bond to four atoms (hydrogen or carbon)
Saturated
What does saturated mean?
All bonds with other atoms are single bonds
What are alkane uses and why?
Fuels (low reactivity but combust well)
What is the general formula of alkanes?
CnH(2n+2)
What is a homologous series?
A series of compounds with the same general formula
What is the general formula of alkenes?
CnH2n
What makes alkenes more reactive than alkanes?
Their C=C functional group
Why are alkenes unsaturated?
They contain a double bond between two of their carbon atoms (C=C)
How many more hydrogen atoms does an alkane with the same number of carbon atoms have compared to an alkene?
2
What is the formula of pentene?
C5H10
What is produced from an alkene and hydrogen?
An alkane
nickel catalyst present
What is adding hydrogen to an alkene called?
Hydrogenation
What is produced from an alkene and oxygen?
Carbon monoxide + carbon (soot) + water
or
Carbon dioxide + water
Is the combustion of alkenes and oxygen complete or incomplete?
Incomplete so they burn with smoky flames
What is produced from an alkene and a halogen?
A colourless solution
shaken with bromine water
How can alkenes and alkanes be distinguished?
Shaken with bromine water, alkenes turn colourless from orange-brown
What is produced from an alkene and water (steam)?
Alcohols
phosphoric acid catalyst
What are properties of carbon monoxide?
Colourless
Toxic
Odourless
What is created when alkanes are burned with a lack of oxygen?
Carbon monoxide
What does the combustion of hydrocarbons when there is good air supply involve?
Energy release
Oxidation of carbon and hydrogen creates carbon dioxide and water
What is the functional group of alcohols?
Hydroxyl (-OH)
What can alcohols be dehydrated to form?
Alkenes
What is the general formula of alcohols?
CnH2n+1OH
What is the formula for butanol?
C4H9OH
What are the alkanes in order?
Methane Ethane Propane Butane Pentane Hexane
What do alcohols release when combusting?
Energy
How do we measure the temperature change of combusting alcohols?
1) Measure mass of alcohol and burner before and after combustion of fuel
2) Measure temperature of water before and after to find temperature change
3) Divide temperature change by mass of fuel used to find mass needed to heat water up by 1 degree
What must be considered when measuring the temperature change of combusting alcohols? (3)
Heat energy is lost to surroundings so draft insulators minimise heat loss
Heat energy is used to heat the glass instead of the water
Some water can evaporate
What do alcohols and air (and heat) produce?
Carbon dioxide and water
What do alcohols and sodium produce?
Hydrogen
What do alcohols and water produce?
They dissolve to give neutral solutions
What do alcohols and oxidising agents produce?
Carboxylic acids
What happens to carboxylic acids in water?
They partially ionise (weak acids)
What is the functional group of carboxylic acids?
Carboxyl (-COOH)
What is the general formula of carboxylic acids?
CnH2n+1COOH
What is the formula of butanoic acid?
CH3CH2CH2COOH
How do carboxylic acids react with water?
They dissolve to give solutions with an acidic pH
What does the reaction of carboxylic acids and alcohols (and an acid catalyst) produce?
An ester and water
What is produced from the reaction of carbonates and carboxylic acids?
A salt
Carbon dioxide
Water
How can alcohols be oxidised? (2)
Oxygen in air
Oxidising agent
What is the process of fermentation?
1) Add yeast to sugar solution
2) Aqueous ethanol solution and carbon dioxide form
3) Fractionally distill ethanol mixture for higher ethanol concentration
What are the ideal conditions for fermentation?
37 degrees C
Slightly acidic solution
Absence of oxygen (anaerobic)
What are polymers?
Large, chain-like molecules made from monomers
What are polymers held together by?
Strong covalent bonds between atoms in molecules
Weak intermolecular forces between molecules
What are properties of polymers?
Usually solid at room temperature
Melt easily due to weaker intermolecular forces than chemical bonds
What are the monomers of addition polymerisation?
Alkenes due to their C=C bond opening
What are the products of addition polymerisation?
Only the polymer
What is the naming process of polymers?
‘poly’ (monomer)
Why are intermolecular forces stronger in polymers than small molecules?
Polymers are bigger
What is condensation polymerisation?
The joining of monomers with 2 functional groups to producer larger polymers and small by-products
What is the simplest type of condensation polymerisation?
2 monomers with identical functional groups
diol + dicarboxylic acid –> polyester + water
Why do polymers cause many wastage problems?
They do not biodegrade (break up easily)
Why are plastics difficult to recycle?
Many different types of plastic need to be sorted
What happens when plastic is combusted?
Toxic acidic gases are released
What are problems with polymers? (4)
Landfill sites
Difficulty recycling
Combustion releases harmful chemicals
Expensive
What are advantages of synthetic polymers?
Recycling reduces crude oil usage
Combustion releases energy
Non-biodegradable so do not rot
What are disadvantages of synthetic polymers?
Burning releases toxic gases
Sorting and recycling is expensive
What are the naturally occurring polymers? (4)
Starch
Cellulose
DNA
Proteins
What are the monomers of starch and cellulose?
Sugars
What are the monomers of proteins?
Amino acids
What are the monomers of DNA?
4 different nucleotides