Need quick re-cap on basics. (1 Viewer)

[Forbidden.]

1)

There's bond a and bond b

Which one is the covalent double bond and which one is the coordinate
covalent bond ?

2)

The qualitative test for water hardness is the lather of soap, but what's
the quantitative test for water hardness ?

 

[wrxsti]

1) "b" is the co-ordinate covalent bond, as both electrons are provided by the 1 atom for sharing

2) Quantative test : (what ive got for this) precipitation with a known volume of Na2CO3 then drying and weighing precipitate......
You could write AAS i guess?

 

[sh1n1gam1]

1) bond B is the coordinate covalent bond.

2) You can use titration with EDTA or measure it gravimetrically by precipitating the ions in the water with a carbonate.

 

[Forbidden.]

thnx guys

 

[xiao1985]

one thing to add: titration of EDTA using enriochrome black-T as an indicator. turning point is when purple turns blue (IIRC)

now something which you don't know for the HSC: ozone infact exist in a resonance structure. so whilst the picture depicts ozone having 1 double bond and 1 single bond. in reality, what observed is that ozone has 2 1.5 bonds (again, no need to know this for hsc)

what you DO need to know, is that coordinate covalent bond, once formed, has exact same property as normal covalent bond.

 

[Chinmoku03]

Actually, yeah, my friend had a uni friend who was talking to us about ozone today.

http://img108.imageshack.us/my.php?image=ozonepq0.jpg

He said that the pink bonds alternate in linking the green dotted oxygen and the red dotted oxygen and there's no actual coordinate covalent bond forming :S It's nice to know this, but I guess I shouldn't go against BOS in the HSC, right?

 

[xiao1985]

coordinate covalent bond is a very obscure idea...

and your friend is absolutely right, the other bond alternates between the two oxygen atoms.