• Best of luck to the class of 2024 for their HSC exams. You got this!
    Let us know your thoughts on the HSC exams here
  • YOU can help the next generation of students in the community!
    Share your trial papers and notes on our Notes & Resources page
MedVision ad

Mod 8 - memorising cation/anion elimination flowchart + solubility rules (1 Viewer)

SadCeliac

done hsc yay
Joined
Sep 23, 2021
Messages
2,516
Location
Sydney <3
Gender
Male
HSC
2023
Does anyone have any patterns or tips on memorising cation/anion elimination charts?

the chart I am memorising is attached...

Also anyone have tips for memorising solubility rules??? NAGSAG // PMS CaStroBear doesn't seem to work properly :/ and our school hasn't given us another one
 

Attachments

Last edited:

carrotsss

New Member
Joined
May 7, 2022
Messages
4,453
Gender
Male
HSC
2023
You don’t need to memorise it, just remember that everything on the solubility constants list in insoluble and that’s pretty much all of them
 

SadCeliac

done hsc yay
Joined
Sep 23, 2021
Messages
2,516
Location
Sydney <3
Gender
Male
HSC
2023
You don’t need to memorise it, just remember that everything on the solubility constants list in insoluble and that’s pretty much all of them
But aren't there exceptions to the solubility list on the formula sheet?
 

carrotsss

New Member
Joined
May 7, 2022
Messages
4,453
Gender
Male
HSC
2023
But aren't there exceptions to the solubility list on the formula sheet?
I don’t think there’s many (I’ve never run into one), having a solubility below 0.01M makes something insoluble and pretty much everything on there has a solubility well below 0.01M except for a couple of ones, and it’d be easier to remember the few exceptions rather than all that confusing castrobear nagsag nagsag stuff
 

SadCeliac

done hsc yay
Joined
Sep 23, 2021
Messages
2,516
Location
Sydney <3
Gender
Male
HSC
2023
I don’t think there’s many (I’ve never run into one), having a solubility below 0.01M makes something insoluble and pretty much everything on there has a solubility well below 0.01M except for a couple of ones, and it’d be easier to remember the few exceptions rather than all that confusing castrobear nagsag nagsag stuff
hmm i guess i never thought of that
 

SadCeliac

done hsc yay
Joined
Sep 23, 2021
Messages
2,516
Location
Sydney <3
Gender
Male
HSC
2023
Does anyone have any patterns or tips on memorising cation/anion elimination charts?

the chart I am memorising is attached...

Also anyone have tips for memorising solubility rules??? NAGSAG // PMS CaStroBear doesn't seem to work properly :/ and our school hasn't given us another one
to be more specific, are there tricks to memorise for when they ask for a flowchart (that's why im asking about the cation/anion elimination)? because we need to memorise specific tests and colours of precipitates... that's the stuff that i find hard to memorise
 

carrotsss

New Member
Joined
May 7, 2022
Messages
4,453
Gender
Male
HSC
2023
to be more specific, are there tricks to memorise for when they ask for a flowchart (that's why im asking about the cation/anion elimination)? because we need to memorise specific tests and colours of precipitates... that's the stuff that i find hard to memorise
for flowcharts just use the data sheet, usually there will only be one precipitate at each stage so it’ll be kinda obvious. there’s only a couple of things that make weird coloured precipitate and ik this is weird but I feel like they’re the ones you’d expect ig. flame tests are a thing ig, most colours are what you’d expect as well (like copper being being blue-green is just intuitive), the only major exception is barium and calcium which are like opposites of what you’d expect.

sorry ik this is probably not very helpful it’s just the way my really weird brain works 😭😭
 

SadCeliac

done hsc yay
Joined
Sep 23, 2021
Messages
2,516
Location
Sydney <3
Gender
Male
HSC
2023
for flowcharts just use the data sheet, usually there will only be one precipitate at each stage so it’ll be kinda obvious. there’s only a couple of things that make weird coloured precipitate and ik this is weird but I feel like they’re the ones you’d expect ig. flame tests are a thing ig, most colours are what you’d expect as well (like copper being being blue-green is just intuitive), the only major exception is barium and calcium which are like opposites of what you’d expect.

sorry ik this is probably not very helpful it’s just the way my really weird brain works 😭😭
I'm gonna be real - I reread that and it makes no sense to me 😭 sorry please try again?
 

carrotsss

New Member
Joined
May 7, 2022
Messages
4,453
Gender
Male
HSC
2023
I'm gonna be real - I reread that and it makes no sense to me 😭 sorry please try again?
honestly I don’t think I’m the right person to explain this my brain memorises things super weird lmao
 

SadCeliac

done hsc yay
Joined
Sep 23, 2021
Messages
2,516
Location
Sydney <3
Gender
Male
HSC
2023
formula sheet solubility table?
no but like flowchart and colours and the method questions



like when they go 'write a method to distinguish between three unknown samples, one of which is X Y Z where theyre all anions/cations' idrk
 

carrotsss

New Member
Joined
May 7, 2022
Messages
4,453
Gender
Male
HSC
2023
no but like flowchart and colours and the method questions



like when they go 'write a method to distinguish between three unknown samples, one of which is X Y Z where theyre all anions/cations' idrk
for those ones just see what’s insoluble on the formula sheet and then make a test so one is eliminated each time. for the colours I usually just guess lol, most of the colours are pretty predictable and only a couple are colourful
 

TankKuno

Well-Known Member
Joined
Nov 5, 2022
Messages
296
Gender
Male
HSC
2023
for those ones just see what’s insoluble on the formula sheet and then make a test so one is eliminated each time. for the colours I usually just guess lol, most of the colours are pretty predictable and only a couple are colourful
:0
 

user18181818

Active Member
Joined
Sep 12, 2023
Messages
231
Gender
Female
HSC
2023
flame tests colours u should memorise tbh i don't memorise ppt colours they're usually white except for copper
to distinguish between the anions/cations here is the general gist
ANIONS
- red litmus (separate acids from bases) --> cl-, i-, so42-, and br- will stay red as they are acidic whilst oh-, ch3coo-, co32-, po43- will become blue as they are basic
ACIDS
-add agno3 which will form a ppt with cl-, i- and br- whilst so42- will be in a solution
- then add dil nh3, cl- will dissolve, then add conc nh3, br- will dissolve
BASES
- add hno3, co32- will produce bubbles (carbon dioxide)
- add fe(no3)2-, oh- and po43- will ppt (oh- is a brown ppt whilst po43- is yellow) whilst ch3coo- will remain in solution

CATIONS
- add hcl, ag+ and pb2+ will ppt whilst others won't
- add nh3, the ag+ ppt will dissolve whilst pb2+ won't
- with the rest, add h2so4, ba2+ and ca2+ will ppt whilst the others won't
- do a flame test from there to differentiate all of them

basically the only ppt colours i memorise is iron hydroxide (brown) and iron phosphate (yellow)
hope that helps
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top