Ch - 19 (Reactions to organic compound) Flashcards
Define fossil fuels.
A substance which when burned, releases heat energy
What are the most common fossil fuels?
coal, natural gas, petroleum
What is methane?
the main constituent of natural gas and is a hydrocarbon.
What are hydrocarbons made up of?
Hydrogen and carbon atoms
How are fractions in petroleum separated?
fractional distillation
Define petroleum.
- a mixture of hydrocarbons which also contains natural gas
- Crude oil
- thick, sticky, Black liquid that is found under porous rocks
what does molecule in each fraction have?
- similar properties
- similar boiling points (depends on number of carbon atoms)
- contain alkanes
what is the size of each molecule in a fraction related to?
How many carbon and hydrogen atoms the molecules contains
What is fractional distillation carried out in?
-Fractionating column which ahs temp gradient
- hot at bottom n cool at top
What happens during the process of fractional distillation?
- crude oil heats up and vaporizes
- vapor of hydrocarbons enters the column which has a temp gradient
- vapor with high b.p. condense at bottom of the column.
- vapor of hydrocarbons with lower b.p. rise up the column and Condense at the top.
What are the main properties of fractions?
- Viscosity
- M.p. / B.p.
- Volatility
Describe detailS about viscosity.
- ease of flow of liquid
- High viscosity are thick & flow less easily
- no. of carbon atom increases, attraction between hydrocarbon molecules increases
- liquid becomes more viscous, increasing length of hydrocarbon chain
- going down column, viscosity of fraction increases
Describe details about M.p. / B.p.
- molecules get larger, intermolecular attraction becomes greater
- more heat is needed to sperate molecules
- going down the column, b.p. of fractions increases
Describe details about volatility.
- tenancy of a substance to vaporize
- size of hydrocarbon increases, attraction between molecules increases
- going down column, volatility of fractions decreases
What are the uses of fractions?
- Refinery gas: Heating and cooking
- Gasoline: Fuel for cars
- Naphtha: Raw product for forming chemicals
- Kerosene: For making jet fuel
- Diesel: Fuel for diesel engines
- Fuel oil: Fuel for ships and home heating
- Lubricating oil: Lubricants, polishes, waxing
- Bitumen: Surfacing roads
What are alkanes?
Group of saturated hydrocarbons
What does the term saturated mean?
- Have single carbon - carbon bonds
- covalent bonds (only non metals)
what is the general formula of alkane?
CnH2n+2
What is a physical description of alkanes?
- colorless compounds
- hugs change of colorless compounds
What are the properties of alkanes?
- unreactive compounds
- undergo combustion reactions
- cracked in small molecules
- React with halogen in presence of light
What is chemical equation of methane undergo complete combustion?
CH4 (g) + 2O2 (g) –> CO2 (g) + 2H2O (l)
What are the names of alkanes?
- Methane
- Ethane
- Propane
- Butane
- Pentane
What is molecular formula of:
- Methane
- Ethane
- Propane
- Butane
- Pentane
- Methane = CH4
- Ethane = C2H6
- Propane = C3H8
- Butane = C4H10
- Pentane = C5H12
What happens in substitution reaction of alkanes with halogens?
- one atom (or group of atoms) is wrapped with another atom (or group of atoms)
- undergoes substitution in presence of UV radiation
- called photochemical reaction
- UV light provides activation energy for reaction
- hydrogen atoms is replaced by halogen atom
What are alkenes?
- unsaturated hydrocarbons
- double bonds (C = C)
- covalent bonds
What is general formula for alkene?
CnH2n
What does double bonds in alkenes mean?
- make more bonds of other atoms by opening up the bond
- carbon atom forms 4 single bonds
- more reactive than alkanes
What are the names of alkenes?
- Ethene
- Propene
- But - 1 - ene
- Pent - 1 - ene
What is the molecular formula of alkenes?
- Ethene (C2H4)
- Propene (C3H6)
- But - 1 - ene (C4H8)
- Pent - 1 - ene (C5H10)
How are products made from by manufacturing of alkenes?
long chains of hydrocarbons molecules are further processed
What process is used to convert longer chain molecules into short chain and more self hydrocarbons?
Catalytic cracking
What are the products in catalytic cracking?
- Shorter chain alkenens
- alkene
- hydrogen
What is cracked to produce petrol, other alkenes and hydrogen?
Kerosene and diesel oil
Describe the process of catalytic cracking.
- cracking involves heating the hydrocarbon molecules to 600 - 700 °C to vaporize them
- vapour passes to hot powdered catalyst of alumina or silica
- breaks covalent bonds in molecules, come in contact with surface of catalyst causing thermal decomposition
- molecules broken randomly forming a mixture of alkanes and alkenes
- hydrogen and more alkene is produced at higher temp.
What is an experiment to distinguish alkenes from alkanes?
- bromine water is an orange colored solution
- when bromine is shaken with an alkane, solution remains orange
- when bromine is shaken with alkene, solution goes colourless
What are addition reactions?
- Alkene undergo addition reactions in which atoms of a simple molecule add across the C = C bond
- only one product is formed
What are the different addition reactions alkene goes through?
- Alkene and bromine
- Alkenes and hydrogen
- Alkenes and steam
What is an example of an addition reaction?
- Reaction between bromine and ethene
- 2 bromine add across the carbon - carbon double bond to form a saturated compound
- bromine water is orange but becomes colourless
What happens when alkene undergo addition reaction with hydrogen?
- Alkane is formed
- nickel catalyst
- Ethen and hydrogen produces ethane, propene and hydrogen will form propane and so on
What happens when alkene undergoes an addition reaction with steam?
- alcohol is formed
- since water is added, it is called a hydration process
- requires acid catalyst
- ethene reacts with steam to produce ethanol, propene will react with steam to produce propanol
What are alcohols?
homologous series of compound
What do all alcohols contains?
Hydroxyl (OH) which is responsible for the characteristic reactions
What are the names of all alcohols
- Methanol
- Ethanol
- Propanol
what is the molecular formula of alcohols?
- Methanol (CH3OH)
- Ethanol (C2H5OH)
- Propanol (C3H7OH)
What is one of the most important alcohols?
- Ethanol
- Structural formula: CH3CH2OH
Describe w few properties of ethanol.
- found in alcoholic drinks
- fuel in cars as solvent
- undergo complete combustion and burn in excess oxygen to produce carbon dioxide and water
What is the symbol equation of ethanol in complete combustion?
C2H5OH (l) + 3O2 (g) –> 2CO2 (g) + 3H2O (l)
What are the 2 methods of manufacturing ethanol?
- hydration of ethene with steam
- fermentation of glucose
Describe the process of hydration of ethene in production of ethanol.
- a mixture of ethene and steam is passed over a hot catalyst of phosphoric acid at a temp of 300 °C
- Pressure : 60 atmospheres (6000kPa)
- gaseous ethanol is condensed into liquid for use.
Describe the process of fermentation of glucose in production of ethanol.
- sugar or starch is dissolved in water and yeast is added
- fermented between 25°C to 35°C with absence of oxygen for a few days
- Yeast contains enzymes that catalyse the breakdown of starch or sugar to glucose
- If temperature is too low the reaction rate will be slow and if it is too high enzymes will become denatured
- yeast respire anaerobically using glucose
- yeast is killed off once the concentration of alcohol reaches 15 % so reaction vessel is emptied
- batch process
What is the symbol equation of yeast respiring anaerobically using glucose?
C6H12O6 —> 2CO2 + 2C2H5OH
What is the equipment required for:
- Hydration of ethene
- Fermentation
- Hydration of ethene - complex setup
- Fermentation - simple equipment
What is the raw materials required for:
- Hydration of ethene
- Fermentation
- Hydration of ethene - non renewable resources (crude oil)
- Fermentation - renewable sources (sugar cane)
What is the type of process for:
- Hydration of ethene
- Fermentation
- Hydration of ethene - continuous process (a steam of reactants is constantly passed over to a catalyst)
- Fermentation - batch process (mixed together in a reaction vessel and left for several days and process is repeated again)
What is the rate of reaction for:
- Hydration of ethene
- Fermentation
- Hydration of ethene - fast
- Fermentation - very slow
What is the quality of product for:
- Hydration of ethene
- Fermentation
- Hydration of ethene - produces pure ethanol
- Fermentation - produces a dilute solution requiring further processing
What is the atmospheric effects for:
- Hydration of ethene
- Fermentation
- Hydration of ethene
- no greenhouse gases
- pollutant produced from burning fossil fuels
- Fermentation
- CO2 (greenhouse gases)
What are the reaction conditions for:
- Hydration of ethene
- Fermentation
- Hydration of ethene
- High temp and pressure required increasing energy input and cost
- Fermentation - low temp required
What do carboxylic acids react with?
- metals to form a salt and hydrogen
- carbonates to form a salt, water and carbon dioxide gas
- bases to form a salt and water
What is the ending of all salt formed my carboxylic acids?
Anoate
What are the products formed in a reaction when:
- Carboxylic acid reacts with a metal
- Carboxylic acids react with carbonates
- Carboxylic acid reacts with hydroxides
- Metals - salt and hydrogen gas
- Carbonates - metal salt, water, andCO2 gas
- Hydroxides - salt and water
What are the 2 methods used to make carboxylic acids?
- Oxidation by fermentation
- using oxidizing agents
What happens in the process of making carboxylic acid by oxidation (fermentation)?
- Microbial oxidation (fermentation) of ethanol will produce a weak solution of vinegar (ethanoic acid)
- when bottle of wine is opened up
- bacteria in air (acetobacter) will use atmospheric oxygen from air to oxidise ethanol in wine
what is the symbol equation when microbial oxidation happens in ethanol to produce carboxylic acid?
C2H5OH (aq) + O2 (g) –> CH3COOH (aq) + H2O (l)
What happens in the process of making carboxylic acid by using oxidising agents?
- vinegar taste of wine when it has been left over for days is because of ethanoic acid
- potassium manganate (VII) is used as oxidizing agent
- ethanol is heated with acidified potassium manganate (VII) in the presence of an acid
- heating is performed under reflux, with a mixture in vessel and condenser attached to the top
- Condenser prevents volatile alcohol from escaping the reaction vessel because alcohols have less boiling points
what is the symbol equation for the process of maxing carboxylic acid using oxidizing agents?
CH3CH2OH (aq) + + 2[O] –> CH3COOH (aq) + 2H2O (l)
what is observed in the process of maxing carboxylic acid using oxidizing agents?
- solution changes from purple to colorless
- oxidizing agent is represented by
What makes esters?
- Alcohol and carboxylic acids
- by esterification reaction
What are esters?
Compounds with the functional group R - COO - R
Describe esters property.
- sweet smelling oily liquids used in food flavorings and perfumes
What is required for esterification process?
Acid catalyst
How is ethyl ethanoate formed?
Ethanoic acid will react with ethanol in the presence of concentrated sulfuric acid (catalyst) to form ethyl ethanoate
What is the symbol equation of the formation of ethyl ethanoate?
CH3COOH (aq) + C2H5OH (aq) —> <— CH3COOC2H5 (aq) + H2O (l)
How do we names esters?
First part: Length of carbon chain in alcohol and ends with ‘yl’
Second part: Length of carbon chain in carboxylic acid and ends with ‘oate’
What is the name of ester when:
Alcohol: Propanol
Carboxylic acid: Methanoic acid
Propyl methanoate
What is the name of ester when:
Alcohol: Methanol
Carboxylic acid: Buatnoic acid
Methyl buatanoate
What is the name of ester when:
Alcohol: Ethanol
Carboxylic acid: Popanoic acid
ethyl propanoate
