Question

Based on the mass of barium sulfate (0.46g), calculate the mass of sulfate in a 0.7g sample of alum.

I think I did this right but i'm not sure.
0.46g BaSO4/233.37g BaSO4=0.002mol BaSO4
0.002mol BaSO4 x 1mol SO4/1molBaSO4=0.002molSO4

Answer 1

I don't understand the question. You calculated mols only, not grams.
I can calculate g sulfate or I can calculate grams sulfate in a 0.7 g sample of alum but I don't understand what the two have to do with each other.

Answer 2

In the second half of the experiment 3mL of hydrochloric acid and 30mL of barium chloride were reacted with a 0.7g sample of alum to get barium sulfate.
The question says based on the mass of barium sulfate (0.46g), calculate the mass of sulfate in your sample of alum.

Answer 3

Then you have done it right for mols but you didn't calculate sulfate. And the 0.7 g alum doesn't have anything to do with the problem (unless you wanted to calculate percent sulfate in the sample).
I obtained 0.00197 mols BaSO4 which is 0.00197 mols SO4 and that x 96.064 = g sulfate. That gives me 0.189 g which if tghe 0.46 is all of your number, then I would round the 0.189 to 0.19g.