Fuels and Fire Explained - GCSE Chemistry: Alkanes

[00:00:00]Disclaimer, please do not try this at home.

[00:00:05]Yeah, I know you said you wanted to sort of start >> Small.

[00:00:07]>> Small. Yeah.

[00:00:08]>> Why do you want to start small?

[00:00:10]>> Because I don't want to start with a massive flame on my hand.

[00:00:13]>> [laughter] >> Do you want me to test it for you?

[00:00:16]>> Do you want me >> want to test it? Yeah.

[00:00:17]>> Let me let me test it for you.

[00:00:18]>> Just for the record, this isn't fair.

[00:00:20]It's just that Andrew really likes fire.

[00:00:22]>> Yeah, scoop a small bit off like that.

[00:00:24]>> Wait wait wait. You've got anything flammable on you at all?

[00:00:26]>> No.

[00:00:27]>> Wow, that is incredible.

[00:00:30]>> Did you Did you feel any heat?

[00:00:31]>> No.

[00:00:32]>> Just for the record, he was terrified and I [music] was calm about this. I was like, "Andrew, don't worry about it."

[00:00:41]>> Um right, should we start?

[00:00:43]>> So, grab grab some from anywhere will do really. This one.

[00:00:53]We'll just test it.

[00:01:04]Was it hot?

[00:01:05]Was it hot?

[00:01:08]>> That was actually I said I wrote it down. That scream was off script.

[00:01:12]Did I get as much as you?

[00:01:13]>> No.

[00:01:14]>> No.

[00:01:17]I'd rather get my wisdom tooth out again to be honest.

[00:01:19]I'm being completely honest with you.

[00:01:20]>> Get a bit more then.

[00:01:23]>> You're bullying me. More.

[00:01:24]>> Yeah.

[00:01:26]>> That's too much though, all right.

[00:01:28]Okay.

[00:01:29]This is GCSE chemistry. Today we're looking at alkanes.

[00:01:45]Andrew, I told you not to worry about it. It's fine. I don't know why you guys are getting so stressed about it. It's fine. Just shoot a fire.

[00:01:52]Today we are learning about four hydrocarbon fuels. By the end of this video, you'll know all the alkanes you need for your exam, and most students get this wrong. Hydrocarbons are molecules made from hydrogen and carbon only. There are four hydrocarbons you need to [music] know.

[00:02:08]Methane, ethane, >> [music] >> propane, and number four, the one most students forget, butane. And if you can't remember that, use this mnemonic.

[00:02:20]Monkeys eat purple bananas, where the first letter of each word >> [music] >> represents the name of the alkane.

[00:02:27]Monkey, methane, eat, ethane, purple, propane, bananas, butane.

[00:02:33][music] All right, names done. Now, I want you to pay attention to something.

[00:02:39]The number of carbons in each alkane.

[00:02:43]Methane has one, ethane has [music] two, propane has three, and butane has four.

[00:02:53]Formulas. I'm going to show you a pattern, and if you spot it, you're ahead of most students.

[00:02:59]For every carbon you have, there are double the number of hydrogens plus two.

[00:03:04]We're going to do some questions on that, but before we do, let's do a summary.

[00:03:09]Methane, ethane, and propane, butane, those are the first [music] four alkanes. Alkanes, these are the things they contain, carbon and hydrogen only.

[00:03:16]Here's how arranged, look at the chains.

[00:03:18]It all starts [music] with methane, burns with this flame, CnH2n+20.

[00:03:24]General formula, clock it, double the number of hydrogens [music] on it, add two extra H, now you've got it. Butane's next for this topic, follow the general formula for it. That's now got one more carbon in this, that means [music] it's now C2H6.

[00:03:36]Now, try these questions. We're going to go through the answers straight after.

[00:03:41]What is the general formula for the homologous series of alkanes?

[00:03:53]>> [music] >> All right, for the first question, which says What is the general formula for the homologous series of alkanes? The answer is, of course, 2. And the reason for that is whatever number of carbons you've got, you need double the number of hydrogens, plus you've got a hydrogen on each end of your alkane, which [music] makes it the plus two. So, you've always got double the number of hydrogens in an alkane plus the two at the ends.

[00:04:23]Which of the following is the correct name for an alkane with four carbon atoms? Butane, pentane, ethane, or propane? [music] >> [music] >> Now, for question two, which is Which of the following is the correct name for an alkane with four carbon atoms? And you just need to remember the scheme [music] there. Methane, ethane, and propane, butane. These are the first four alkanes. Butane is the fourth alkane.

[00:04:52][music] Butane alkane. Butene would be an alkene. Um so, therefore, that's how you remember that one.

[00:04:59]What is the name of the alkane that has three carbon atoms surrounded [music] by eight hydrogen atoms?

[00:05:15]If you're looking for a textbook or a series of textbooks that cover the concepts I cover in GCSE science, I have got my own book series, the Wrapping Up Science Revision Guide series, for biology, physics, and chemistry, which you can purchase yourself using the link under this video on Amazon today. And for the third question, what is the name of the alkane shown in a displayed formula as a chain of three carbon atoms surrounded by three hydrogen atoms?

[00:05:43]Well, of course, if you've got three, remember the rhyme. Methane, ethane, and propane, butane.

[00:05:48]>> [music] >> Propane is the third one. Propane has got three carbons. That's your answer.

[00:05:53]If you've learned at least one thing from this video, please like and subscribe. And remember, if there's something else you want to learn across chemistry, biology, and physics, you can look across all the videos on my channel on Mac the rapping >> [music] >> science teacher.