Sorry, I have been stuck on this question. I would appreciate if someone could help me out.

Approx how many mL of 0.25M BaCl2 solution would be required to precipitate all the sulfate if we assume the sample is pure sodium sulfate? Assume that the density of the barium chloride solution is 1.00g/mL. Thank you!

4 answers

Na2SO4 + BaCl2 ==> BaSO4 + 2NaCl

So how much Na2SO4 do you have?
It is not stated. The above question is all the information given.
That's why you've been stuck on this question for hours. There isn't enough information. You MUST know how much Na2SO4 there is.

This is just like asking "You're driving your car to the supermarket that's down the road 5 miles. How long will it take you to get there? Without know the speed of the car you can't calculate the time.
Well at least I don't feel so bad for not being able to figure out the problem. Thanks for your help!