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captainhyderabad

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Q.7 what deductions can be made from the following observations on a crystalline compund K? explain your answers
A) when heated gently it gave off a colourless vapour that condensed on the side of the test tube. the liquid turned blue cobalt chloride paper pink
B)K was dissolved in water the solution formed was divided into three parts
i) part 1 sodium hyrdoxide solution was addded and the mixture heated. A gas was given off that turned moist red litmus paper blue .
ii)part 2 aqueous ammonia was added and a blue precipitate was formed the precipitate was soluble in excess aqueous ammonia
iii)the solution was acidified with HCL and then (barium chloride)BCL was added A white precipitate was formed.
 
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examman

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Examman to the rescue!

Q.7 what deductions can be made from the following observations on a crystalline compund K? explain your answers
A) when heated gently it gave off a colourless vapour that condensed on the side of the test tube. the liquid turned blue cobalt chloride paper pink

Answer : It's water. Because water turns Blue Cobalt Chloride paper pink. :)

B)K was dissolved in water the solution formed was divided into three parts
i) part 1 sodium hyrdoxide solution was addded and the mixture heated. A gas was given off that turned moist red litmus paper blue .

Answer: It is ammonia gas. Because, When ammonia gas touches moist (containing water) red litmus paper it'll turn it blue as it'll form Ammonium hydroxide (an alkali)

ii)part 2 aqueous ammonia was added and a blue precipitate was formed the precipitate was soluble in excess aqueous ammonia


Answer: Its contains copper. Because copper(II) ions will give blue precipitate. Once aq.Ammonia is added in excess it'll dissolve giving light blue solution. :)

iii)the solution was acidified with HCL and then (barium chloride)BCL was added A white precipitate was formed.

I think part of the question is missing??

NOTE: ANSWERS ARE NOT GURANTEED TO BE 100% ACCURATE. I TAKE NO RESPONSIBILITY FOR A WRONG ANSWER. IT MAY BE CORRECT (MOST PROBABLY IT IS) JUST HEAR OTHERS OPINIONS AS WELL. :D
 
abcde

abcde

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^That's correct! :good:
Yeah,part (iii) seems incomplete. It may have something to do with the identification of sulphate ions, though. (white ppt.of BaSO4)
 
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examman

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In that case I am sorry to inform you that I don't know the answer!
But I strongly sense that some part is missing from the question..

GOOD LUCK in finding the answer :good:
 
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