[GoldShadow]

One of my lab partners was talking about this... can 500M sulfuric acid exist? Is it the same as 98% sulfuric acid?

[Borek]

How could you check it? Do you know how to convert concentrations?

[GoldShadow]

Well... if 98% sulfuric acid means 98% by mass, then that's 98g of H₂SO₄ per 100g H₂O.  98g of H₂SO₄ is about 1 mol, and 100g H₂O is about 0.1 L, which means that it's about 10M.

And for 500M you'd need 500 mols H₂SO₄ per liter of water, right?  Which translates to about 49.045 kg of solid H₂SO₄!  Seems unrealistic to me, but at the same time I can't find the solubility of solid/anhydrous H₂SO₄ anywhere.

[Borek]

You are on the right track, even if wrong in terms of numbers.

Well... if 98% sulfuric acid means 98% by mass, then that's 98g of H₂SO₄ per 100g H₂O.

No, per 100g of solution. Which means 98g of H₂SO₄ per 2 g of H₂O.

Pure H₂SO₄ is liquid miscible with water.

Check out these two pages:

http://www.chembuddy.com/?left=concentration&right=percentage-to-molarity
http://www.chembuddy.com/?left=CASC&right=density_tables

[GoldShadow]

Ah, I see what I did wrong.  So 98g, or 1 mol of H₂SO₄ divided by 2g, or 0.002L of H₂O, gives 500M after all.

Thanks for your help, I appreciate it!

[AWK]

Ah, I see what I did wrong.  So 98g, or 1 mol of H₂SO₄ divided by 2g, or 0.002L of H₂O, gives 500M after all.

Thanks for your help, I appreciate it!

You misunderstood two different concentations - molar (moles/dm³) and molal (moles/kg_of solvent).
In fact, 98 % H2SO4 is approximately 500 molal (m) not molar (M)

Edut: typo that made answer ambiguous corrected.