[perpetualconfusion]

Hi,

I am having trouble with these quals from hell (you have to figure everything based on your unknowns)

So I cannot find these answers anywhere on the internet:

(All cations)
What gives a white flame color?
What gives a thick yellow precipitate?
What give a bright yellow (not sodium, that's more orange) as in these smiley face yellow flame color?
If your is dark blue, what are the possible cations?
Is the solution of cobalt pink?
And what are distinctive features that you can tell apart from Mg, Al, and Zn?

Thanks

[tennis freak]

Hi,

I am having trouble with these quals from hell (you have to figure everything based on your unknowns)

So I cannot find these answers anywhere on the internet:

(All cations)
What gives a white flame color?
What gives a thick yellow precipitate?
What give a bright yellow (not sodium, that's more orange) as in these smiley face yellow flame color?
If your is dark blue, what are the possible cations?
Is the solution of cobalt pink?
And what are distinctive features that you can tell apart from Mg, Al, and Zn?

Thanks

Well for the third one, it might be potassium, the fourth may be copper, and the fifth i think is purple not pink.

[wereworm73]

Which cations are possible in your unknown? I'm assuming Na⁺, Mg²⁺, Al³⁺, Zn₂₊ and maybe Co²⁺ are some of them.  These sort of experiments usually discuss the reactions of certain cations so you'll know what to look for when you do tests on the unknown.

 

[wereworm73]

Potassium salts color the flame violet, though it isn't very intense and sodium impurities can easily mask it.

[Will]

What gives a white flame color?

Magnesium and Aluminium (I think)

What gives a thick yellow precipitate?

Cu₂O.nH₂O is a yellow precipitate and I think AgI is as well.

What give a bright yellow (not sodium, that's more orange) as in these smiley face yellow flame color?

I think sodium is the yellowest you can get! Try burning a bit of sodium carbonate in a flame.

If your is dark blue, what are the possible cations?

Many cations! See http://woelen.scheikunde.net/science/chem/solutions/index.html

Is the solution of cobalt pink?

[Co(H₂O)₆]²⁺ is pink.

And what are distinctive features that you can tell apart from Mg, Al, and Zn?

Do you mean chemical tests or features that you can tell apart by looking at it, or testing its physical properties?

Thanks

You're welcome!

[wereworm73]

Wow.  Here you go, will.  Let me know what cations are in this scooby snack.

[Will]

Wow.  Here you go, will.  Let me know what cations are in this scooby snack.

Thank you . I also found a couple of good links which might help with the colour of flames, based on the composition and properties of some fireworks:
http://www.unitednuclear.com/formulas.htm and http://dwb.unl.edu/Teacher/NSF/C07/C07Links/hmchemdemo.clt.binghamton.edu/zumdahl/docs/chemistry/07atomstructure/library/07fireworks.htm

[perpetualconfusion]

Wow. You guys are clearly amazing.

 

[AWK]

Hi,

I am having trouble with these quals from hell (you have to figure everything based on your unknowns)

So I cannot find these answers anywhere on the internet:

(All cations)
What gives a white flame color?
What gives a thick yellow precipitate?
What give a bright yellow (not sodium, that's more orange) as in these smiley face yellow flame color?
If your is dark blue, what are the possible cations?
Is the solution of cobalt pink?
And what are distinctive features that you can tell apart from Mg, Al, and Zn?

Thanks

most of  cations do not dye a flame (except: Cu, Ca, Sr, Ba, K, Na, Rb, Cs, B)
Yellow precipitate - AIr, AgBr, Ag3PO4, As2S3, As2S5, BaCrO4, CdS, PbI2 (in increased intensity of yellow)
Calcium resemble sodium, though is more orange
Dark blue - Cr or Cu cations
Yes
Al cation precipitate as Al(OH)3 in the presence of NH4Cl in in close to neutral pH, then after addition of (NH4)2S you can precipitate ZnS, finally addition NaOH will precipitate Mg(OH)2