ATAR Notes: Forum

VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: vea on March 29, 2011, 09:15:43 pm

Title: vea's chem question!
Post by: vea on March 29, 2011, 09:15:43 pm

Hi guys, this thread will contain all my nooby questions for chem. :)

To start off:

In a gravimetric analysis of sulfate in fertiliser, we are precipitating sulfate as barium sulfate.

Before we actually precipitate the sulfate, we added 3ml of 2M HCl. Now I know that the H+ ions are used to make the precipitation specific, preventing OH- from precipitating with Ba2+ and also preventing CO3 2- from precipitating, but what is the purpose of the Cl- ions? I have written down that it is to make sure there are a lot of contaminating Cl- ions but I'm not too sure why you would want this?

Thanks in advanced.

Title: Re: vea's chem question!
Post by: wildareal on April 28, 2011, 12:04:00 am

It is just a spectator ion to keep the Barium ion stable so that it can swap and form Barium Sulphate.

Title: Re: vea's chem question!
Post by: vea on April 28, 2011, 12:27:34 am

Haha I had it cleared up but thanks for the reply!