IIT JEE , AIEEE Forum - Chemistry , Inorganic Chemistry - Today I had board prac. Plz tell if I did it corretly.....

tarinbansal

Today I had my chemistry board practical.

I am not sure whether I detected my salt correctly or not.

I am telling U the appearance of salt. If U know,then please tell me what cud be the salt.

The salt was powder with crystals mixed with that powder. It was white and odourless.

That's what I can tell U. I detected it to be PbSO4.

Am I right???

Please tell me.

zamuka

was the salt soluble in water????

if yes then it can't b lead sulphate.......and as far as I think only water soluble salts are in our syllabus.......incidentally I in my pre board pracs detected the given salt 2 b lead sulphate and my teacher immediately told that I hadn't detected the anion properly..........I think the same prob is with u.....although I am not sure.............

but no prob as though it wudn't cost too much marks.....

spideyunlimited

y wudnt it cost 2 many marks? :S
mera toh aaj tak poora sahi kabhi nahi hua - salt analysis...
when one anion/cation was correct i got 4/8
none correct - > 2/8
then how r u sayin tht?

tarinbansal

R U sure it wudn't cost too much marks?
I am sure about Pb2+ but not at all sure about anion. I did all the 3 tests 3 times and still I was not getting the correct infernce from any test and finally I wrote SO4.

tarinbansal

It seemed to soluble in water.
When I added water to salt, the whole solution became white and it was not at all visible that the salt was settled down or it was soluble. But I strongly feel that it was soluble.

Spidey,
salt analysis is of 6 marks not 8 marks.

zamuka

arey yaar majority of students get it wrong in salt analysis in the pracs........but marks aren't deducted so strictly.......even in gd skuls....

zamuka

tarin I think u must hav got lead acetate or nitrate......bcause they r quite common......did u test for these 2????

spideyunlimited

ok u sure about board practical marks break up.. mujhe bata do plz..

and hamare me toh bahut strict hoti hai marking :( ...
20.5 se upar nahi gaye (outta 30)

oh n computer board prac mein 30/30 .. teacher told me :D

zamuka

20.5!

yaar probably that will b the lowest limit.....

tarinbansal

zamuka,
in case of nitrate, we get reddish brown vapours with conc H2SO4, I did not any coloured vapour.
On adding conc H2SO4, there was just a little reaction. Most of the salt was collected at the bottom of test tube and very less white smoke was coming out of it. I did chromyl chloride also but it was not chloride.
Me very worried.

Spidey,
its Volumetric analysis-10
salt analysis-6
viva + filee-5
content based experiment-4
investigatory project-5

shevchenko

did u test for chloride???

tarinbansal

Yes.
I did chromyl chloride test. In the test when chloride is present and we add conc H2SO4 to pot. dichromate and salt, a very vigorous reaction takes place and a very volatile solution is formed with orange vapours coming out of test tube.
But when I did the test with this salt, no reaction took place, the test tube was silent, no vapours came out of it.

I doubt if any anion was present in that salt. I think it was only cation. The teachers fooled me. :D

shevchenko

yeah hard luck happens sometimes when salt is contaminated......and did u also test with agno3(coz when u say colourless odourless pbcl2 comes to my mind)

tarinbansal

What is the use of testing with AgNO3.
chromyl chloride is a very effective test. When it did not give positive test, I thought that it cant be chloride and didn't proceed with any other Cl test.

Can't it be PbSO4? Becoz after doing the 3 anion tests 3 times, I got exhausted and wrote SO4.

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