Comments on: O Level Chemistry – Qualitative Analysis Cont’d

By: sean

sean — Sat, 31 Oct 2009 15:38:51 +0000

Hi Simon,

Please check my earlier comments to other students.

I will suggest that you draw out a flow chart to see how the information given and linked from one to another.

You would need to have good knowledge of Tests for Cations and Anions though, in order to be able to comprehend that.

Cheers!

By: simon

simon — Mon, 26 Oct 2009 09:00:03 +0000

i am very very very tensed for mu o levels chemistry examination!i hardly know what to do,they are in 2011
gas p will be cabon dioxide
the solution Q will me carbonic acid
and i can’t do that further(look i just lost it in between)
that’s what happends with me!

By: sean

sean — Mon, 15 Dec 2008 04:03:20 +0000

Hi Raymond,

Well done. I live the way you present your workings towards getting the answers also.

Keep it up.

Cheers
Sean
Master Trainer
Author

By: Raymond

Raymond — Mon, 10 Nov 2008 08:38:47 +0000

P is carbon dioxide as it forms a white precipitate with limewater, which is calcium hydroxide.

Q is carbonic acid as that is the product formed when carbon dioxide is mixed with water.

R has to be Barium Nitrate as it is the only soluble barium out there in the syllabus. It could potentially be Barium Hydroxide, but the presence of T takes that possibility away.

S is barium carbonate, as that is the salt formed when carbonic acid reacts with barium nitrate, or any barium solution for that matter.

T is Nitric Acid, as well, I did not even bother thinking about this as the question stated that they had used Devarda’s alloy to test this and the result was ammonia was produced, so nitrate ions HAVE to be present, and therefore, it has to be nitric acid.

By: sean

sean — Mon, 15 Sep 2008 13:36:22 +0000

Well Done Gary.

You are spot on for this question.

For other readers that need more explanations on how gary came out with the answers, do drop us a comment so that we can revert back.

PS: Gary-Do share with us your working/thought process if there is someone that asks about it.

Cheers
Sean