Alkanes Flashcards
1
Q
General formula
A
CnH2n+2
2
Q
Outline fractional distillation
A
- Crude oil is vaporised
- Travel up fractionating column
- Larger hydrocarbons don’t vaporise, stay at bottom + form residue
- Temperature gradient - cooler at top
- Due to diff. carbon chain lengths, diff BP so condense at diff. temp
- Fractions drawn off at diff. levels
3
Q
Define cracking
A
Breaking long chain alkanes to smaller hydrocarbons by breaking C-C bonds
4
Q
Thermal cracking
A
- High temp, high pressure
- Products: alkenes
- Alkenes used to make polymers
5
Q
Catalytic cracking
A
- Zeolite catalyst, slight pressure, high temp
- Products: aromatic hydrocarbon + motor fuels
6
Q
Why is CO bad?
How do you remove it from the exhaust gas?
A
- Poisonous
- Binds to same site on haemoglobin in RBC as oxygen so oxygen can’t be carried around
- Removed by catalytic converters
7
Q
Why is soot bad?
A
- Causes breathing problems
- Builds up in engines so don’t work properly
8
Q
What is the cause of global warming?
A
Greenhouse gases absorb infrared energy + emit it towards the earth
9
Q
Oxides of nitrogen
- Formation
- Consequence
- Solution
A
- High pressure + temp cause N + O<strong>2</strong> in air to react
- Forms ground level ozone, major component in smog - irrates eyes + causes lung problems
- Catalytic converters
10
Q
Acid rain
- Formation
- Consequence
- Solution
A
- Sulfur impurities in fossil fuel react w/ oxygen to form sulfur dioxide gas, dissolves in water + produces sulfuric acid
- Destroys trees, vegitation, kills fish + corrodes buildings
- Powdered calcium carbonate + oxide mixed w/ water to form alkaline slurry → calcium sulfate
11
Q
Free radical
A
Partical w/ unpaired e-
Forms when covelant bond split equally
12
Q
What are the conditions for free radical substitution?
A
UV light
13
Q
Define chlorofluorocarbons
A
Halogenoalkanes where H replaced w/ Cl + F
14
Q
What is the ozone important?
A
- Absorbs UV radiation from sun
- UV causes sunburn + skin cancer
15
Q
What are the properties of CFCs?
What are the alt?
A
- Unreactive, non-flammable + non-toxic
- HFC (hydrofluorocarbons) + hydrocarbons
