Edmund's 1st Year Chem Qns.

[Edmund]

Ok, I'll have lots of questions, so I've created a thread for them.

Which of the following atoms or ions have the smallest radius, and why?







Thanks.

EDIT: Whoops, overlooked something

[chem-nerd]

Na would have the largest radius due to having three occupied shells.

For all of the other options, they all have the same electron configuration of 1s²2s²2p⁶. The only difference then is the core charge experienced by the outer shell electrons.

core charge = no. of protons - no. of inner shell electrons

thus, Na⁺ would have the highest core charge and hence the smallest radius due to the electrons being pulled more strongly towards the nucleus

[Edmund]

From 2005 paper,

A small bubble (2.0mL) rises from the bottom of a lake where the temperature and pressure are 8 deg Celcius and 6.4 atm, to the water surface, where the temperature is 25 deg Celcius and the pressure is 1.0 atm. What is the final volume of the bubble at the water surface?

I tried:

[chem-nerd]

did you get 13.5mL?

[Edmund]

nope, i think thats the answer.

What units did you work with?

[chem-nerd]

P in kPa
V in L
T in K

if you didn't, you probably got 40mL?

[Edmund]

Yep, too lazy to convert =/

Thanks.

[Edmund]

I havent got the answers to these, could anyone check my answers? This one seems tricky:

A1: C
A2: D
A3: C  B

[Ken]

I can agree with u for A1 and A3 but I can't seem to find the 7th one for A2

[mark_alec]

but I can't seem to find the 7th one for A2

benzene ring = 6
amides = 2
carboxylic acid = 1
total:9

[Edmund]

Back again for more questions 

I have to draw all possible stereoisomers for



Are these possible? The answers seem to have other possibilities... There are 3 in total.


Finding oxidation numbers seems easy, but this one's tricky:



Any ideas? Ans: +2 for Manganese

[Toothpaste]

yay coordination complexes

Finding oxidation numbers seems easy, but this one's tricky:



Any ideas? Ans: +2 for Manganese

Na is +1 so everything in that bracket should be -1 all up.

Uhh is that water.. well I'll assume so, therefore counts as 0.

two Cl gives -2
NO2 is -1

therefore Mn has to be +2 to make the bracket -1

[Edmund]

lol thanks, I put 0 as oxidation number for chlorine

[Collin Li]

Good luck with that subject Edmund, I hated it last year (although I still managed to get 92 for it?)

I forgot how to do stereoisomers with those kind of things

[Edmund]

Yeh exam's on Tuesday

Here's an electrochemistry question:

I've calculated in both cells from the pH, subbed into to find . The direction of electrons was therefore determined to be RIGHT to LEFT. Is this correct? Now looking at the next question, how would I find ? I'm not getting the answer...