[GloveK8]

Hi everyone.. I'm new here and i need help seriously on this problem..

I did an experiment in sch on gravimetric analysis... using barium chloride to form barium sulfate..
But there is a few steps tat dont understand about it..
the lab manual list these few steps..

Add 5 drops of concentrated HCL and 50 ml of water to the sulphate solution..
and after that add barium chloride solution...
test for complete precipitation by adding a few drops of barium chloride solution to the supernatant liquid..


I was wondering why HCl is added, is it about the common ion effect, if it was, but HCl is a strong acid and barium chloride is strong electrolyte, how to determine which is stronger?

And why does adding barium chloride solution can test for complete precipitation..

I'm new to the course, that's why i dont't know alot of the things, sorry if they are very simple...
and thanx if anyone can help out with my problems..

[Borek]

I was wondering why HCl is added, is it about the common ion effect, if it was, but HCl is a strong acid and barium chloride is strong electrolyte, how to determine which is stronger?

To lower pH. Many metal hydroxides are weakly soluble and they could copreciptate. You don't want that.

And why does adding barium chloride solution can test for complete precipitation.

Do you know what a limiting reagent is?

[GloveK8]

Icic... Thanx thanx.... haha... i forget all about limiting reagent.. my classmates and i did ask the lecturer about the questions and he cannot answer any one of it, and to think that he has a master degree... thanx xD

[GloveK8]

but is barium chloride metal hydroxide?

[Alberto_Kravina]

but is barium chloride metal hydroxide?

huh?

Do you mean: Is barium chloride a metal hydroxide? If yes, how did you come to this?

[GloveK8]

Ya I am asking if barium chloride is a metal hydroxide... but I thought that barium chloride is a metal salt???

[Alberto_Kravina]

Ya I am asking if barium chloride is a metal hydroxide... but I thought that barium chloride is a metal salt???

It IS a metal salt - a metal chloride. I don't know how you came to the conclusion that it is a metal hydroxide, or has Barium chloride an OH^- group?

[punkdevil]

how do u increase the yield of Barium Sulphate..thanx for helping out..need it ASAP...