National 5 Chemistry 2018/19

Oh I’ll be feeling snazzy after I get them notes

feeling v snazzy atm, got some ace notes and some class notes tee hee

Hey guys, can anyone help me with this question? As usual the understanding of chemistry has no marking scheme (so helpful 🙄). I think it’s asking to do combustion reactions but I have absolutely no clue what the equipment set up would be/how you’d go about it. Is this even in the course anymore?

i’m not 100% sure (open ended questions aren’t my strongest) but you could put each of the substances under a beaker with water in it and light them for a certain length of time and then measure the change in temp n stuff n then use the eqn Eh=cm[delta]T to find which one releases the most energy. i could be completely off but if i was in an exam and that came up then that’s what i would probs do, not sure about the least pollution bit tho soz x

Thanks, that just occurred to me too ahah. Thanks for your help, hopefully something like that doesn’t come up 😊

i’m not 100% sure (open ended questions aren’t my strongest) but you could put each of the substances under a beaker with water in it and light them for a certain length of time and then measure the change in temp n stuff n then use the eqn Eh=cm[delta]T to find which one releases the most energy. i could be completely off but if i was in an exam and that came up then that’s what i would probs do, not sure about the least pollution bit tho soz x

So, what I would do is comment on fuels first of and foremost, make it seem like your marker is a complete idiot and has never took Chemistry for. Everything you mention that you could give a definition on, give it, it also provides for a better understanding to get your point across.

A fuel is a chemical which burns to release energy, and this reaction is known as combustion. Crude oil is extracted from the ground by drilling and sent to a refinery. These fuels are mostly hydrocarbons (perfect example of making the marker out like they had no idea about Chemistry) - which are compounds that contain the elements hydrogen and carbon only, but also some impurities such as sulfur, which can lead to pollution (acid rain) when we burn them. The different hydrocarbons present in the crude oil have different boiling points, and this property is used to separate the different hydrocarbons using a process called fractional distillation. The towards starts with small molecules, and descends to larger molecules in order of increasing boiling points. The higher the boiling point, the more carbon/hydrogen atoms it contains.

A pollutant is a substance which harms the environment. When you burn these fossil fuels, many greenhouse gases are produced, which cause an increase in the planet's temperature - global warming. The more carbon atoms a hydrocarbon contains, the more greenhouse gases it produces

Then you could, like you commented on, could describe the Eh=cmdeltaT for each compound.

There is many other things but I would personally stick to hydrocarbons, and possible even go on to detail different categories, such as alkanes, alkenes, etc.

Fractional Distillation isn’t in the course anymore

Thanks! I guess the question would be worded differently now because Fractional Distillation isn’t in the course anymore

Today I came across this in this year’s specimen paper, and the answer in the marking scheme is listed as C, which has really confused me as I can’t see how that’s right. I put A but can see B as well, just do not get how it is C. I don’t want to make a false accusation of the marking scheme being wrong, so ...is it?

Today I came across this in this year’s specimen paper, and the answer in the marking scheme is listed as C, which has really confused me as I can’t see how that’s right. I put A but can see B as well, just do not get how it is C. I don’t want to make a false accusation of the marking scheme being wrong, so ...is it?

You need to look for the longest carbon chain. Which is 4 carbons.

Oh. But where are there four?

Oh right. Guess that’s bc it’s on the end, but wish they put it in one straight continuous line.

Thanks.

Oh it's not? Oh, well I wasted a bit of time studying that for the examination then lol . Thanks for telling me that, at least I can forget about that when going into the exam hall.

Yeah there’s nothing about it in my 2nd edition of How To Pass Chemistry