Organic Chemistry Flashcards
Homologous series
Same general formula
Similar chemical properties
Gradation in their physical properties
Differ by a CH2 unit
What is a hydrocarbon
A compound/molecule consisting of hydrogen and carbon only
Alkanes
General formula: CnH2n+2, at room temperature and pressure; all colourless gasses (meth/eth/propl/but - ane)
Functional group
Reactive group in a molecule
Complete Combustion (Alkanes)
Products: Carbon dioxide + Water + Heat. Test: For CO2, bubble combustion products through colourless lime water- becomes milky white -CO2 present, for H2O condense the vapour by cooling- add white anhydrous copper(II) sulfate - becomes blue (H2O present)
Incomplete Combustion for alkanes
(Limited oxygen)Products: Carbon Monoxide + water
Problems Carbon dioxide, carbon monoxide, soot, sulfur dioxide (leading to acid rain)
Carbon dioxide: Greenhouse gas- absorbs IR given off by the earth - causes earths surface to warm- sea level rises, flooding, climate change
Carbon monoxide: Toxic gas (as combines with haemoglobin in the blood- reducing capacity to carry oxygen)
Soot: Carbon particles pollute the air- causes lung damage and respiratory problems
Sulfur dioxide: Acid rain- damages buildings ( especially limestone ones), damages vegetation, kills fish in lakes and rivers
Alkenes
General formula: CnH2n
Functional group: Carbon- Carbon double bond (C=C)
At room temp and pressure all colourless gases (eth/prop/but-1/but-2 ene)
Complete combustion of Alkenes
Products- Carbon dioxide + Water ( burns with an orange flame)
Incomplete combustion of Alkenes
(Limited oxygen) Products- carbon monoxide + water (sometimes soot, but don’t put in equation)
Unsaturated
The molecule contains one or more carbon-carbon double bonds
Addition reaction
Two molecules react to form one product
Addition reaction of Alkenes with bromine
Bromine adds across the double bond
Condition: room temp
This reaction is to test for the presence of a C=C bond- If organic substance is a liquid- shake with bromine water. If a gas- bubble the gas into bromine water
Orange bromine water changes to colourless in presence of a C=C bond
Addition reaction with Alkenes and hydrogen
Hydrogen adds across the C=C double bond
Conditions: Temperature 150 degrees Celsius, catalyst of nickel
Reaction called hydrogenation
Addition reactions of Alkenes with steam
Called hydration as water is being added across the C=C double bond
Conditions: Catalyst and high temperatures
What is a Polymer
Is a long chain molecule made from joining small molecules together