 this video we're going to really just touch on a few key things because I will assume that there will be some more things happening in the classroom that we will do in order to cover some of these in a little bit more depth. This is another one of these areas where you can provide a quite large amount of information about each of these areas. So we're looking at environmental, economic and socio-cultural implications associated with the obtaining and use of hydrocarbons from the earth. So there's a lot of aspects to this and we'll as I say just be touching them a little bit in this video. So I think the first thing that we probably need to do is just to set some of these things into a bit of a context. So hydrocarbons themselves are primarily coming from three main sources, all of which are fossil fuels and they are coal, crude oil and natural gas. One of these that provides the greatest range of hydrocarbons for different applications is crude oil. And crude oil has a number of what we call fractions. Now these fractions are present in crude oil and they basically represent a whole range of carbon compounds. So carbon chains from quite small to quite large. We now know that the length of a carbon chain affects its boiling point. The fact that a mixture of crude oil contains a number of different substances all of which have different chain lengths and all of which therefore have different boiling points means a procedure like fractional distillation is a very good technique for separating the components of this mixture. You can see the column that I have on this slide gives us a range of different lengths of carbon chains and also a range of different temperatures at which each of these fractions will come out of a barrel of crude oil. So you can see not only differences in the length of the chains as we move down this column but also in the temperatures associated with their appearance. This allows us to separate the fractions from crude oil and to use them for a wide variety of uses. But when we're considering not only how we obtain hydrocarbons from the earth but also how we use them we need to understand something about the mining process about the process of extraction and also about the energy requirements associated energy required for the extraction of each of these. There are also environmental costs or at least potential environmental costs that are associated with mining and obtaining hydrocarbons from the earth and then there are also economic factors and socio-cultural factors. So all of these are important when we are looking at the use of different types of hydrocarbons that we obtain from the earth.