# Environmental Chemistry Chapter 4 Lesson 2 Energy from Coal

those together we get a grand total of 19 0 6 grams in every mole so the sum all of the atoms added together gives me 1906 now remember the carbon contributed 1620 of that total contribution see what we’ve done this little part here is what we called a conversion factor its percent by mass of carbon that’s a topic we covered together last chapter just part over whole to express a person so that’s the mass percent of carbon part over whole notice what’s happened we can calculate by cancelling our coal variable and end with the carbon so let’s hit that on our calculator you would hit one point I’ve use your scientific notation key for the x 10 value we want that to be 1.5 million so we need six zeros after that and then we want to multiply that by the ratio of 16 20 / 1906 that’s your key sequence on your calculator our original sample of coal times the percent by mass of carbon and we’ve converted into the grams or tonnes because we use tons here as our initial thing so that would be fine we end up with a ratio here of 1.3 and that’s a million so times 10 to the 6th tons of carbon 1.3 million or 1.3 times 10 to the 6th tons of carbon process with me what we just did we had sitting at the coal the power plant one and a half million tons of coal in that one and a half million the vast majority 1.3 million are coming just from the elemental form of carbon it gives us insight into saying coal by the vast majority of its composition is indeed carbon with these few other trace elements depending upon the purity of carbon so petroleum and natural gas started to overtake coal around the 1950 and we saw that in that previous graph we know that petroleum is a mixture of several thousand different compounds in the great majority of these compounds are hydrocarbons so as we begin to explore petroleum and this is now what we consider section 4.4 we start to consider the elements or the other molecules found in petroleum specifically also met natural gas let’s take a quick peek at a very important diagram this is found on page 167 we’re going to be asked to look at the names the formulas the structural formulas and the condensed structural formulas for the first ten hydrocarbons so the first hydrocarbon is the simplest of all it has just one carbon surrounded by four hydrogen’s it’s Lewis dot structure would have a tetrahedral shape if we remember from our molecular geometry where we’d have one central carbon and four hydrogen’s surrounding it we would have a non-polar molecule with polar bonds so when we begin to consider ch4 its structural formula we need to associate that with the word methane the easiest hydrocarbon of all we often hear that called natural gas we burn that in our homes most often as our source of heat in our kitchen as well as in our furnace now notice this that the boiling point and we’ll just kind of keep tab as we start looking at this the lightest of all this is definitely a gas at room temperature negative 164 degrees Celsius is its boiling point so it’s very low boiling point very easy to convince to turn

example if one carbon here at the upper position is attached to a carbon it has positions for three single bonds this carbon here is attached to three other carbons leaving one space open for the hydrogen this looks like it has three spaces open the interior carbons would have two spaces and at the terminal end we need three spaces and then I must also go back and actually add the hydrogen one at a time you’re going to click that H onto your sapling just to show how many hydrogen’s it took to actually satisfy all four bonds for the carbons this is probably faster in your sapling because you just click the element on there where I have to write it on but I want to give you that visual so you can see when you’re done drawing yours in sapling it needs to match mine here we had a straight chain adding hydrogen’s to all the carbons to make sure they have four bonds and even in a branch chain it’s the same game every carbon has to have four bonds anything missing must be the hydrogen well let’s look at an oil refinery how gasoline and other hydrocarbons are produced from petroleum and I know that I’ve given you not only a supplemental video lesson in the early start to kind of talk about this we’ll talk about it in this lesson as well this looks like a good old oil refinery the backbone of the oil industry so how are gasoline and other hydrocarbons produced from petroleum remember this petroleum as thousands of ingredient molecules in there and this process takes place at this oil refinery we know this by looking at I mean this is a very iconic look at the oil industry we take something called crude oil and separated into fractions including the gasoline fraction so if I look at these long skinny towers here in the petroleum oil refinery industry they’re known as the distillation tower and what they do is is kind of talk through what we looked at based on boiling points we can separate out the different fractions in petroleum based on the number of carbons and their boiling points and they kind of separate them out from there so we have this initial step where crude oil is delivered into a boiler as the temperature of the boiler increases notice this flame down here so the crude oil is separated into fractions but it all arrives into this boiler as the boiler increases in temperature compounds with the lowest boiling points to vaporize remember the lowest boiling points are the lightest molecule so the lightest fraction has the lowest boiling point they’re going to come out as vapors which is gases aren’t they things like our methane ch4 things like our ethane c2h6 and things like our propane oops ssbc so c3h8 these are the lightest gases and they come off first up there don’t they at the lightest gases with the lower boiling points they begin to vaporize as the temperature increases even more the boiling points begin to reach those of the heavier molecules and as the heavier molecules begin to rise you start to get things like gasoline coming out down here gasoline remember the major component is octane c 8 h 16 plus 2 is 18 even heavier in this range c 12 to 16 this is where jet fuels is distilled into 14 to 16 and the in the length of the carbon chain is our fuel called diesel down here the reformer is actually connected to our cracker and will actually talk a little bit about what a cracker does what it does is crack the molecule into smaller pieces so for instance if we have these larger molecules coming out let’s say C 15 to 18 let’s say you get a c 16 h 32 and 2 is 34 let’s say you get something coming out here what the cracker will do is actually separate it so if i crack that molecule I could get c 8 and i would get hydrogen’s you know two molecules of c