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apchemstudent
Nov27-04, 08:25 PM
Problem solved... nm thanks for your help though...

so-crates
Nov27-04, 10:05 PM
0.035 L * 3 M of H2SO4 = 0.105 mols of H2SO4
H2SO4 -> 2 H+ + SO42-


Theres your first problem. Polyprotic acids don't disassociate all at once. The correct reaction would be
H_2SO_4 \longrightarrow H^+ + HSO_4^-\ \ \ K_a = high
HSO_4^- \longrightarrow H^+ + SO_4^{2-}\ \ \ K_a = a\ lot\ less

apchemstudent
Nov27-04, 11:01 PM
Theres your first problem. Polyprotic acids don't disassociate all at once. The correct reaction would be
H_2SO_4 \longrightarrow H^+ + HSO_4^-\ \ \ K_a = high
HSO_4^- \longrightarrow H^+ + SO_4^{2-}\ \ \ K_a = a\ lot\ less

Ya, i think my teacher wants to pretend it dissociates completely. However though, that still won't solve my problem. If we pretend only 1 H+ dissociates we have 0.105 moles of H+

(.105 - .075)/3 does not equal .105/4

so-crates
Nov28-04, 12:37 AM
Could you state the exact wording of the problem? What you wrote is rather confusing.

chem_tr
Nov28-04, 01:19 AM
Yes, apchemstudent, please write the exact wording and we will discuss it. It is good that you've made much effort to solve it, and maybe we'll see a little point you may have forgotten.

apchemstudent
Nov28-04, 10:21 AM
figured out the mistake....