Ch - 19 (Reactions to organic compound)
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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