HSC Chemistry Question Thread

[jakesilove]

How does including and outlier affect the validity, reliability and accuracy of results?
(Specifically HSC 2004 q20)

Hey! Including an outlier will effect your reliability, as the average you took will be incorrect (and averages speak to reliability), but it will also effect your validity, as your experimental design didn't include discounting outliers (so I guess it isn't so much the outlier itself that effects validity, but rather your decision not to exclude it, if that makes any sense what-so-ever). It probably doesn't effect the accuracy of your individual measurements, however it will obviously effect how close your solution is to the real value.

[anotherworld2b]

Hi I have some questions
For electrons shells what is the pattern they follow to fill up the shells? I know that the maximum number of electrons is calculated using the 2n^2 but that's not how they fill up each shell?
I also wanted to ask for intermolecular forces how do you know what forces are present in a compound?
I also wanted to ask how do you know the effect of each force on properties like vapour pressure, boiling point and ect?

[jakesilove]

Hi I have some questions
For electrons shells what is the pattern they follow to fill up the shells? I know that the maximum number of electrons is calculated using the 2n^2 but that's not how they fill up each shell?
I also wanted to ask for intermolecular forces how do you know what forces are present in a compound?
I also wanted to ask how do you know the effect of each force on properties like vapour pressure, boiling point and ect?

I can't imagine you need to know how electrons fill shells, but if you do, check out the image here. Just draw consecutive arrows, and the first unit you hit is the next one you fill.

In terms of intermolecular forces; there are always dispersion forces, there are dipole-dipole forces if the molecule is polar, and there are hydrogen bonds if there are Hydrogen groups and F-O-N groups present in the compound.

No idea how to answer that last part, sorry!

THIS IS LARGELY NOT HSC MATERIAL!

[RuiAce]

Hi I have some questions
For electrons shells what is the pattern they follow to fill up the shells? I know that the maximum number of electrons is calculated using the 2n^2 but that's not how they fill up each shell?
I also wanted to ask for intermolecular forces how do you know what forces are present in a compound?
I also wanted to ask how do you know the effect of each force on properties like vapour pressure, boiling point and ect?

Q1 There actually IS no defined pattern in general. Every row of the periodic table follows a different trend.
Q2 Well, you just look at what you have, and see what substances are polar. Feel free to provide three questions though.
Q3 It's... the same for each forces I believe...

THIS IS LARGELY NOT HSC MATERIAL!

Emphasis on this^

[jakesilove]

Q1 There actually IS no defined pattern in general. Every row of the periodic table follows a different trend.
Q2 Well, you just look at what you have, and see what substances are polar. Feel free to provide three questions though.
Q3 It's... the same for each forces I believe...Emphasis on this^

There is actually a defined pattern, which only messes up on elements who half fill their d-shells (I think? Something like that). Anyway, I did chem so long ago that all I remember is that image aha

[g98]

Hi, I have a heap of questions so here I go :
1. what is the difference between nuclear reactors and cyclotrons? And what particles are used in each? And how do you know which one radioisotope is made in?
2. How do you know what type of radiation a radioisotope gives off when decaying?
3. Other than acid rain is there any other impact of SO2 and oxides of nitrogen in the atmosphere?
4. What's an example of a natural buffer? is CO2 + H20 --> H2CO3 (in equilibrium) one?
5. Whenever you use a sintered glass funnel do you use a side arm flask and vacuum and do you have to mention that in experiments?
Thanks!!

[anotherworld2b]

thank you for the help 
I was also wondering if I could get help understanding markonikoff's rule. I am not sure how it works

[RuiAce]

There is actually a defined pattern, which only messes up on elements who half fill their d-shells (I think? Something like that). Anyway, I did chem so long ago that all I remember is that image aha

I wouldn't know of this lol

thank you for the help 
I was also wondering if I could get help understanding markonikoff's rule. I am not sure how it works

This isn't in the HSC course at all (unless Jake can handle it)

[jakesilove]

Hi, I have a heap of questions so here I go :
1. what is the difference between nuclear reactors and cyclotrons? And what particles are used in each? And how do you know which one radioisotope is made in?
2. How do you know what type of radiation a radioisotope gives off when decaying?
3. Other than acid rain is there any other impact of SO2 and oxides of nitrogen in the atmosphere?
4. What's an example of a natural buffer? is CO2 + H20 --> H2CO3 (in equilibrium) one?
5. Whenever you use a sintered glass funnel do you use a side arm flask and vacuum and do you have to mention that in experiments?
Thanks!!

1. Nuclear reactors bombard elements with neutrons. Cyclotrons accelerate charged particles (eg. electrons) and smash those into elements. You don't really need to know which is which in terms of your radioisotope, but if you ever have an equation where neutrons are added, then that's a nuclear reactor!

2. You just have to know. If it emits an electron, beta negative decay. If it emits a positron, beta positive decay. If it emits an alpha particle (He), alpha decay and if it emits a fast gamma ray, it's gamma radiation. Just know what type of emission your radioisotope undergoes, and why that is useful!

3. Nup, we really only care about acid rain. Potentially, it's a pollutant, as it's toxic to breathe in?

4. Yep, you can use that, or the standard HPO3/P2PO3 one

5. I have no idea what any of those words mean. Sorry aha

[jakesilove]

I wouldn't know of this lolThis isn't in the HSC course at all (unless Jake can handle it)

I don't think AnotherWorld is from NSW

[RuiAce]

3. Nup, we really only care about acid rain. Potentially, it's a pollutant, as it's toxic to breathe in?

Yeah respiratory problems with sulfur dioxide matters. But yeah at the same time only just those two

I don't think AnotherWorld is from NSW

I know aha

[jakesilove]

thank you for the help 
I was also wondering if I could get help understanding markonikoff's rule. I am not sure how it works

But no, I have no clue

[RuiAce]

5. Whenever you use a sintered glass funnel do you use a side arm flask and vacuum and do you have to mention that in experiments?

Umm if you used the sintered glass funnel yes I reckon both are necessary.

[g98]

Thanks for your help! I do have a couple more questions though:
1. if the titrate is in the burette, what do you call the solution in the flask...is it always just standard solution?
2. do soaps form miscelles only when they are around particles are are the always in miscelles even when not surrounding grease...if that makes sense?
3. What is chain stiffening and what is it's effect?
4. Do you need to know the name and structure of a fat or oil like glycerol tristreate for saponification?
Thanks!

[Ayyddaan]

Two identical ships are sunk in seawater. One is sunk in shallow water (60 m)
and the other in deep water (4000 m). Explain how the rusting processes differ
in these two ships. Include equations in your answer.  (7m)

Need some help with this, could somebody write a proper response to it?