Hydrocarbons Flashcards
What is a hydrocarbon?
A compound made up of hydrogen and carbon only.
What is the formula for alkane hydrocarbons?
C(n)H(2n+2)
What is the formula for alkenes?
C(n)H(2n)
What are the first ten hydrocarbons?
Methane Ethane Propane Butane Pentane Hexane Heptane Octane Nonane Decane
Why are alkenes unsaturated?
Because they have a double bond
Why are alkanes saturated?
Because they have a single bond
How many bonds can carbon atoms have?
4 bonds
What are covalent bonds?
A bond between non metal atoms
What are intermolecular forces?
The attraction (force) between molecules that holds them together.
How are hydrocarbons separated? How are they broken?
1) Fractional distillation
2) Cracking
What temperature is crude oil heated to, in order for it to evaporate? What is this known as?
1) 350 degrees
2) Vaporisation
Are short or long chained hydrocarbons more useful?
Short chained hydrocarbons
What state are the shorter chain hydrocarbons in after fractional distillation?
Gases
What state are the longest chain hydrocarbons in after fractional distillation?
Residues
What is a fraction?
A group of hydrocarbons with similar properties and chain lengths, obtained from distilling crude oil
In a fractional column, where will longer chained hydrocarbons settle? Why?
They will settle towards the bottom of the fractional column because they have longer chains, meaning a larger surface area, and therefore more heat is needed to break their intermolecular forces
In a fractional column, where will shorter chained hydrocarbons settle? Why?
They will settle towards the top of the fractional column because they have shorter chains, meaning a smaller surface area, and therefore less heat is needed to break their intermolecular forces
What is cracking and how does it work?
A process which involves breaking the covalent bonds in longer chained hydrocarbons to form, more useful, shorter chain hydrocarbons
In terms of hydrocarbons, what is formed after cracking has taken place?
A shorter chain alkane and an alkene
