Re: Why is petroleum a polymer, while gasoline is not?

Janelle

You are quite correct in noting that gasoline is a 'cracked' product of 
petroleum [crude oil] and also are correct in noting that neither of these 
materials are polymers.

One of the simplest monomers [i.e., the block that is used to build polymers] 
is ethylene 2HC=CH2. If you string 3 or 4 or 5 ethylenes together, you'll have 
the basic part of gasoline. But gasoline is not made by polymerizing ethylene --
 it is made by catalytically degrading petroleum from C20 to C8 fractions.

If you string together [polymerize] ethylene you will get the familiar solid 
polyethylene of garbage bags, milk jugs and a huge variety of other products.

In between ethylene monomer [a gas], gasolene [a low viscosity liquid] and 
polyethylene [a solid plastic] there is another class of materials called 
oligomers. These are neither liquids or solids but pastes and gels --  
somewhere in between. Paraffin wax is an example of a high molecular weight 
oligomer and petroleum jelly [petrolatum, Vaseline]] is an example of a lower 
molecular weight oligomer. Both of these can rightfully be called polymers 
[albeit of low molecular weight]

It would not surprise me if your poster maker substituted the word petroleum  
for petrolatum in the presentation.

Ken