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last SG · 2015-08-19T22:54:00+00:00

Topic : atomic radius Hi! This is from singapore cambridge nov a level exam year 2010,Paper 1 qn 1Qn: which element has the largest atomic radius?BrKKrScSo...

Flying grenade SG

propadiene

https://en.m.wikipedia.org/wiki/Propadiene

https://www.dropbox.com/s/rr1pgyyed7lt9k2/Screenshot_2016-10-02-16-23-31-1.png?dl=0

chankimseng understanding org chem page 25

he writes : explain why CH2=C=CH2 is not a flat molecule(does he mean that propadiene is not planar??) ,

and the molecule on page26 is not planar

how to explain?

sp2 C, sp C , sp2 C are planar ain't it?

UltimaOnline SG

propadiene

https://en.m.wikipedia.org/wiki/Propadiene

https://www.dropbox.com/s/rr1pgyyed7lt9k2/Screenshot_2016-10-02-16-23-31-1.png?dl=0

chankimseng understanding org chem page 25

he writes : explain why CH2=C=CH2 is not a flat molecule(does he mean that propadiene is not planar??) ,

and the molecule on page26 is not planar

how to explain?

sp2 C, sp C , sp2 C are planar ain't it?

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Flying grenade SG

thanks god

Flying grenade SG

chan kim seng book

https://www.dropbox.com/s/wozo7xi9hlqcz6l/20161003_103104-1.jpg?dl=0

whats the diff between break and overcome

Why cannot use break?

is it cannot use 'break' becos IMF will always be present?

what are we doing when we are melting or boiling a substance? overcoming IMF of attractions/interactions?

UltimaOnline SG

chan kim seng book

https://www.dropbox.com/s/wozo7xi9hlqcz6l/20161003_103104-1.jpg?dl=0

whats the diff between break and overcome

Why cannot use break?

is it cannot use 'break' becos IMF will always be present?

what are we doing when we are melting or boiling a substance? overcoming IMF of attractions/interactions?

Stop reading notes / books and spamming your own conceptual qns, and starting practicing 2016 Prelim papers and asking questions from there.

Yes, yes.

Flying grenade SG

NH3 condenses at -33°c (it's boiling point)

boiling point H2 = -253°c

boiling point N2 = -196°c

Flying grenade SG

why NH3 forms liquid from the gaseous state most easily?

Hbonding allows molecules to come together , so less energy needed to condense it?

Flying grenade SG

Mr of H2 = 2 gmol-1

Flying grenade SG

i thought stronger IMF yields higher BP, not lower BP?

update : yes statement is correct

Flying grenade SG

update :

stronger IMF higher BP, weaker IMF lower BP

for stronger IMF, less energy required to condense the gaseous molecules to its liquid

weaker IMF requires more energy to condense it's gaseous molecules to it's liquid

Flying grenade SG

cool the environmental temperature such that the KE of molecules is reduced and hence do not have sufficient KE to overcome the intermolecular forces of attractions and hence IMF becomes significant and hence the liquid is formed

UltimaOnline SG

Be careful. You keep indulgently OCD thinking about conceptual ideas over and over again, it may give you the self-consolation that you understand your Chemistry better than your peers, but in the end you'll still lose out to your peers (in terms of A level grade) who spend the time practicing lots of Prelim papers instead of self-indulgently fantasizing and nitpicking about concepts.

I don't blame you for having the obsessive-compulsion to want to fully sort out your conceptual ideas, but this is physical incarnation and you gotta strike a balance with practicality. It's no use understanding your concepts better than your peers, yet still score a worse final grade than them due to lack of practice of exam papers under exam conditions.

Flying grenade SG

ooh H2SO3 is a weak acid ?

H2SO4 is a strong acid right

Flying grenade SG

conjugate base of H2SO3 isn't stable?

Flying grenade SG

so2(g) forms an equilibrium in water with so2(aq)

UltimaOnline SG

ooh H2SO3 is a weak acid ?

H2SO4 is a strong acid right

Eh you jialat lah, your overly simplistic statement shows a lack of BedokFunland JC depth of understanding of acid-base equilibria.

H2SO4 is a diprotic acid. The 1st proton dissociation is complete hence is technically strong (ie. stronger than hydroxonium ion). the 2nd proton dissociation occurs incompletely in aqueous solution, yet to a significant extent, hence HSO4- is technically weak (ie. weaker than hydroxonium ion) but is still considerably acidic (HSO4- is actually even more acidic than Al3+).

H2SO3 is a diprotic acid. The 1st proton dissociation occurs incompletely in aqueous solution, yet to a significant extent, hence H2SO3 is technically weak (ie. weaker than hydroxonium ion) but is still considerably acidic (H2SO3 is actually even more acidic than Al3+). The 2nd proton dissociation is rather weak (ie. significantly weaker than hydroxonium ion), and simultaneously considering both the acidic and basic hydrolysis of the amphiprotic HSO3- ion, the pH of a solution containing only the HSO3- ion would be only approximately 4.5 (ie. HSO3- is actually even weaker an acid compared to Al3+).

Flying grenade SG

https://www.dropbox.com/s/obib20r7ffbrr8n/20161003_225535-1.jpg?dl=0

i can only think if low temp due to cold water may not provide the necessary energy needed to overcome Ea barrier

how does the hydrolysis of SiCl4 being exothermic affects the extent of rxn? what's the link?

UltimaOnline SG

https://www.dropbox.com/s/obib20r7ffbrr8n/20161003_225535-1.jpg?dl=0

i can only think if low temp due to cold water may not provide the necessary energy needed to overcome Ea battier

how does the hydrolysis of SiCl4 being exothermic affects the rxn? what's the link?

Barrier, not battier. That's it liao. Move on.

Flying grenade SG

http://sgforums.com/forums/2297/topics/441379?page=2

Temperature is actually more important than limited/excess water. (Just as temperature is the more important factor when determining oxidation of alkenes to diols versus oxidative cleavage, over other factors such as pH and concentration).

Flying grenade SG

dk the link between exo and temp . no equilibria involved also

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