Chemistry Forum

If sulfat anions discharge on anode in sulfuric acid
producing persulfuric anions (S₂O₈)₂-. But if this happens in melted sulfate producing SO₃ and O or SO₂ and O₂. Why? What conditions effect on this processes? 100% sulfuric acid is not conducting current but if in 100% acid soluble the sulfate (example Al₂(SO₄)₃) then this liquid will conduct current. And what we get in anode space in this liquid? (S₂O₈)₂- or SO₃ + O?

Af anybody know books about this thematic please give a links.

No

In diluted sulfuric acid or solution of sulfate salts, SO₄ 2- will be not discharged, instead of Oxygen will be developed.
2 H₂O + 2 SO₄ 2- => 2 H₂SO₄ + O₂ + 4e-

In molten alkalisulfates peroxodisulfate will be created. Technical method to produce persulfates

2 SO₄ 2- => S₂O₈ + 2 e-

https://en.m.wikipedia.org/wiki/Sodium_persulfate

If heavy metal sulfates are used they get decomposed to sulfuroxide, oxygen and remaning oxides.

Heavy metal like a iron?

Correct.

100% H₂S04 have no water and electrolytic creating the oxygen by discharge OH- anions is impossible this liquid have no OH- anions and have no H₂O. It's a pure sulfuric acid.

Sulfate of Sulfuric acid will convert to peroxodisulfate, further to disulfate and sulfurtrioxide.

2 SO₄ 2-=> S₂O₈ 2- + 2 e-

2 S₂O₈ 2- => 2 S₂O₇ 2- + O₂

S₂O₇ 2- => SO₄ 2- + SO₃

If i make electrolysis melted NaHSO₄ what i get Na₂S₂O₈ or SO₃ + O?

ChenBeier wrote: ↑Sun Mar 17, 2024 12:25 pm Sulfate of Sulfuric acid will convert to peroxodisulfate.

2 SO₄ 2-=> S₂O₈ 2- + 2 e-

But where this happened? In liqud sulfuric acid or in melted sulfate? Why peroxidsulfate not created in melted sulfates because high temperature? Peroxidsulfat anions will destroing by temperature or what?

Water free sulfuric acid is like a melted sulfate. Alkalisulfates will stop at Peroxodisulfate, iron, chromium and others decompose to sulfuroxides.

But water free sulfuric acid not conducting current (because H₂SO₄ molecule is associated). But if i soluble sulfate in water free sulfuric acid i get current conducting liquid. The question what i get on anode when will do electrolisis in this liquid?

Conc. sulfuric acid has an conductivity of 1,044 · 10−2 S/cm.

It has an autoprotolysis like water

2 H₂SO₄ => H₃SO₄+ + HSO₄-

A sulfate salt enhance because more HSO₄- is produced

H₂SO₄ + Na₂SO₄ => 2 NaHSO₄

Ok! But how about anode processes in this liquid ( H₂SO₄ + Na₂SO₄ without water)?

That I wrote above already

Ok. If we will do electrolisis of melted NH₄HSO₄ (easy melting just 150°C) what we will get SO₃ + O or (NH₄)₂S₂O₈?