Alkanes Flashcards
1
Q
What is an alkane?
A
- a saturated hydrocarbon containing C-H bonds only
2
Q
Are their bonds polar? Why/why not?
A
- non polar
- carbon and hydrogen have similar electronegativities
3
Q
Which intermolecular forces do they have?
A
- only van de waals forces as bonds are non polar
4
Q
Are they soluble in water? why?
A
- insoluble because they have no polar bonds
5
Q
How reactive are alkanes?
A
- very unreactive
6
Q
Which reactions will alkanes undergo?
A
- combustion and reaction with halogen
7
Q
What is crude oil? How is it formed?
A
- mixture of hydrocarbons with similar boiling points
- formed at high temperatures and pressures deep below earth surface over millions of years (non renewable)
8
Q
What is fractional distillation and how does it work?
A
- crude oil is heated until mostly vaporised
- passed into a fractionating tower that is cooler at the top than the bottom
- vapours rise up the column and condense at the fraction that is at the temperature of their boiling points
- shortest chain hydrocarbons condense at the top as they have the lowest boiling points
9
Q
What is cracking and why is it done?
A
- process of turning a long chain alkane into a shorter chain alkane
- shorter chain alkanes are more economically valuable
10
Q
What are the conditions for thermal cracking?
A
- 700 - 1200K
- up to 7000kPa
11
Q
What are the conditions for catalytic cracking?
A
- lower temp
- lower pressure
- zeolite catalyst
12
Q
What are the main products of catalytic cracking?
A
- cycloalkanes, aromatic hydrocarbons, branched alkanes
13
Q
What is incomplete combustion and what products are formed in the case of alkanes?
A
- combustion a limited supply of oxygen
- CO - carbon monoxide - poisonous
- C - carbon - particulates - soot - global dimming
14
Q
Which type of hydrocarbons are most likely to undergo incomplete combustion?
A
- longer chains
15
Q
What is the environmental impact of carbon monoxide?
A
- it is toxic/poisonous
