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Name the compound

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blueyedevil | 10:08 Thu 16th Nov 2006 | Science
7 Answers
Its a powder.
When you add aqueous sodium hydroxide and gently warm it, ammonia gas can be smelt and it turns red litmus paper blue.
once dissoved in distilled water;
when aqueous barium chloride and dilute hydochloric acid are added it goes cloudy white with a white powder precipitate at the bottom of the test tube.
when dilute aqueous ammonia is added it turns a deep powdery blue/green then separates with paler powdery colour at the bottom.
when aqueous potassium iodide and aqueous starch are added it turns a pale yellow colour then if left it tuns a pale orangey/brown colour.

Can you name the anions and cations in this compound?
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Do you want me to do your homework for you or were you doing a practical this morning?
Been pondering this one all day, Gef, I nearly replied earlier today (at work) -but cancelled at the last minute because I wasn't entirely sure. (Who needs Google when you have books....)

Tests 1 & 2 say ammonium sulphate.

The latter tests seem to contradict this - or at least make it ambiguous. blueyedevil, are you sure you have copied out your homework correctly?

And please be precise.

"it turns a pale yellow colour"

"it turns..blue/green"


are these the colours of the solutions, precipitates, suspensions or what?

Are we looking for a single anion and cation? (your question asks "name the anions and cations - so are we looking for more than one of each?)

Are they complex compounds?

Science is all about being precise. If you are asking about the tests for several different compounds, then say so.
If, experimentally, you have found the results you state, then you should ask;

Name the compound
It is (not 'its a') <state colour here> (eg white / purple / colourless etc.)
<state appearance and 'state' here> (eg. amorphous / crystalline solid, or 'colourless solution' etc.)

It reacted with <state reagent here> causing <state effect> (eg effervescence / colour change / precipitate / explosion / visible (coloured) gas / gas that can be smelt / gas that turns litmus paper red or blue etc etc.)

That way, your question is unambiguous and we can have a go at answering it, rather than thinking you have combined the results of three experiments into one question!
Hmm, ammonium sulphate did you say brachiopod?

How about an alum? Now, which one could it be?
Ignore my drunken ramblings......

: #(
LFAO! Oh dear Brachi....
Ok, no response from bluey so either the homework has been done or he (she) has lost interest.

I agree with brachi. The sodium hydroxide test shows the presence of the ammonium ion and the barium chloride/hydrochloric acid test the presence of the sulphate (rather than sulphite ion).

The deep blue/green bit suggests the presence of copper(II) ions but bluey's description is very vague. If copper(II) ios were present then there would be an initial pale blue precipitate of copper(II) hydroxide but the addition of excess ammonia solution would produce a deep blue colour.

Also, if copper(II) ions were present the addition of potassium iodide would produce a pale yellow colour (iodine) but then the addition of starch would produce a blue black colour with the iodine.

It's over to you now bluey.
I think bluey has precipitated off, Gef.

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