[swati]

How can we estimate chloride and sulphate present in the same solution ?

Can we use AgNO₃ first to estimate chloride & then in the remaining solution only sulphate is present which can be estimated using BaCl₂?

Am I correct?

[Borek]

What is Ag₂SO₄ solubility?

[Hispania]

I think Ag₂SO₄ is only partially soluble (k_ps=1,4*10^-5 M³), so it must be difficult to do.

I´d add BaCl₂, calculate SO₄ (BaSO₄ is insoluble), and filter the white solid.
Then (when there´s not SO₄ in solution) I´d add AgNO₃ and calculate Cl^- (knowing the quantity of BaCl₂ we have added to subtract later).

[Borek]

Then (when there´s not SO₄ in solution) I´d add AgNO₃ and calculate Cl^- (knowing the quantity of BaCl₂ we have added to subtract later).

Think about the way to avoid subtraction.

[Hispania]

Then (when there´s not SO₄ in solution) I´d add AgNO₃ and calculate Cl^- (knowing the quantity of BaCl₂ we have added to subtract later).

Think about the way to avoid subtraction.

O.K.. How about using Ba(NO₃)₂ instead of  BaCl₂?

[Borek]

O.K.. How about using Ba(NO₃)₂ instead of  BaCl₂?

Much better.

Note that I was asking about Ag₂SO₄ solubility not to suggest its use, but to signal the fact that OP idea was faulty - using Ag⁺ will precipitate BOTH chlorides and sulfates at the same time, so no separation was possible.

[swati]

 
I thought something but I rejected that case myself & now I am unable to think anything else . I am totally confused what to do . Please help me

[Hispania]

I thought something but I rejected that case myself & now I am unable to think anything else . I am totally confused what to do . Please help me

1-Add Ba(NO₃)₂ to the solution.
2-Calculate SO₄ (I do it with UltraViolet).
3-Filter the white solid.
4-Add AgNO₃ to the solution.
5-Calculate Cl^- (I do it with titration).

[swati]

 I think we can also do it gravimetrically. But I have few doubts :-

1.)  While estimating Cl^- we add dil HNO₃ first & then AgNO₃ in order to prevent the formation of other Ag salts such as phosphates or carbonates. Will dil HNO₃  prevent the formation of  Ag₂SO₄ ?

2.) First we do the gravimetric analysis for Cl^- & then do we have to test for SO4 ^2- in the supernatant solution of chloride estimation or we have to do it separately that is taking new solution

[Dude]

It is nice to think along the lines of wet chemistry, but I would definitely use ion chromatography to quantify the chloride and sulfate content simultaneously.  Even this method will be problematic if the sample is highly complex (ie other anions are present). 

[swati]

No , other anions are not present. Only chloride & sulphate are present. I was just telling the role of adding dil HNO₃

[swati]

I think we can also do it gravimetrically. But I have few doubts :-

1.)  While estimating Cl^- we add dil HNO₃ first & then AgNO₃ in order to prevent the formation of other Ag salts such as phosphates or carbonates. Will dil HNO₃  prevent the formation of  Ag₂SO₄ ?

2.) First we do the gravimetric analysis for Cl^- & then do we have to test for SO4 ^2- in the supernatant solution of chloride estimation or we have to do it separately that is taking new solution

Please someone clear these doubts 

1-Add Ba(NO₃)₂ to the solution.
2-Calculate SO₄ (I do it with UltraViolet).
3-Filter the white solid.
4-Add AgNO₃ to the solution.
5-Calculate Cl^- (I do it with titration).

When we add Ba(NO₃)₂ to the solution containing Cl^- & SO₄ ^2- , I think Ba(NO₃)₂ react with Cl^- to give BaCl₂ .
Am I correct?

[Borek]

When we add Ba(NO₃)₂ to the solution containing Cl^- & SO₄ ^2- , I think Ba(NO₃)₂ react with Cl^- to give BaCl₂ .
Am I correct?

Yes, you are.

Since when BaCl₂ is weakly soluble?

[Albert]

No, you precipitate the SO₄^2- and, then, you can calculate the concentration of Cl-.

[Borek]

While estimating Cl^- we add dil HNO₃ first & then AgNO₃ in order to prevent the formation of other Ag salts such as phosphates or carbonates. Will dil HNO₃  prevent the formation of  Ag₂SO₄ ?

Partially. That's all about equilibrium and protonation of SO₄^2-.

2.) First we do the gravimetric analysis for Cl^- & then do we have to test for SO4 ^2- in the supernatant solution of chloride estimation or we have to do it separately that is taking new solution

It was already said why and how you should start with SO₄^2- determination.