Chemical Forums

Please login or register.

Login with username, password and session length

Sponsored links

Pages: [1]   Go Down

Author Topic: Base strength of hydrogen peroxide?  (Read 1442 times)

0 Members and 1 Guest are viewing this topic.

snorkack

  • Regular Member
  • ***
  • Mole Snacks: +5/-1
  • Offline Offline
  • Posts: 48
Base strength of hydrogen peroxide?
« on: April 10, 2018, 09:12:10 AM »

Where could the base strength of hydrogen peroxide be found?
H2O22 is quoted to be weakly acidic: for the reaction
H2O22 ::equil:: HOO-+H+
the pKa is about 10-12, with comparison to the reaction
H2O ::equil:: HO-+H+
whose pKw is 10-14
But what is the equilibrium constant for the reaction
H2O2+H3O+ ::equil:: H3O2++H2O?
I see that 100 % H2O2 is a solvent whose dielectric constant is close to that of water. Many polar salts possess similar solubility in hydrogen peroxide as in water, only slightly different - in either direction.
How do strong acids behave?
H2SO4 tends to incorporate peroxide as ligand to S.
But HCl has no such option.
So how soluble is HCl in concentrated H2O2?
Also how stable is H3O2+ cation towards loss of oxygen? H2O2 is liable to decay, but it is sluggish. Does strongly acidic reaction catalyze the decay, or not?
Note that HCl can itself stabilize hydrogen peroxide as a diluent. Hydrogen peroxide in high concentrations is liable to thermal runaway - less so at lower concentrations. Since concentrated HCl in water is under 60 % water, concentrated HCl in hydrogen peroxide might also be stabilized by the limited amount of hydrogen peroxide present...
Logged

Enthalpy

  • Chemist
  • Sr. Member
  • *
  • Mole Snacks: +219/-51
  • Offline Offline
  • Posts: 2628
Re: Base strength of hydrogen peroxide?
« Reply #1 on: April 13, 2018, 01:53:37 AM »

[...] H2O2 is liable to decay, but it is sluggish [...] Hydrogen peroxide in high concentrations is liable to thermal runaway [...]

In high concentration, it can and does detonate brutally. Many impurities catalyse the decomposition of H2O2, and in high peroxide concentration the detonation is probable.

Piranha solution suggests that acidity alone doesn't decompose reasonably concentrated H2O2. Some H2O2 remains free in the mix, and it doesn't decompose immediately.
Logged

snorkack

  • Regular Member
  • ***
  • Mole Snacks: +5/-1
  • Offline Offline
  • Posts: 48
Re: Base strength of hydrogen peroxide?
« Reply #2 on: April 13, 2018, 09:36:14 PM »

[...] H2O2 is liable to decay, but it is sluggish [...] Hydrogen peroxide in high concentrations is liable to thermal runaway [...]

In high concentration, it can and does detonate brutally. Many impurities catalyse the decomposition of H2O2, and in high peroxide concentration the detonation is probable.
Does H2O2 ever explode by deflagration rather than detonation?
Piranha solution suggests that acidity alone doesn't decompose reasonably concentrated H2O2. Some H2O2 remains free in the mix, and it doesn't decompose immediately.
That´s H2O2/H2SO4. What is the prevalent form of peroxide in piranha solution? H3O2+, or H2SO5/HSO5-?
Logged

Enthalpy

  • Chemist
  • Sr. Member
  • *
  • Mole Snacks: +219/-51
  • Offline Offline
  • Posts: 2628
Re: Base strength of hydrogen peroxide?
« Reply #3 on: April 16, 2018, 05:29:09 AM »

H2O2 can decompose slowly, or run away thermally, or make boom. I didn't check whether it deflagrates or detonates. Anyway, it's wise to avoid concentrations above 70% as far as possible.

I don't feel the prevalent form determines the stability. Even if the minor form decomposes, all will disappear.
Logged

snorkack

  • Regular Member
  • ***
  • Mole Snacks: +5/-1
  • Offline Offline
  • Posts: 48
Re: Base strength of hydrogen peroxide?
« Reply #4 on: April 18, 2018, 01:50:45 AM »

H2O2 can decompose slowly, or run away thermally, or make boom. I didn't check whether it deflagrates or detonates. Anyway, it's wise to avoid concentrations above 70% as far as possible.

I don't feel the prevalent form determines the stability. Even if the minor form decomposes, all will disappear.
But at a considerably slower rate. And if the equilibrium between forms is also slow, this further prevents runaway decomposition.
Logged

Enthalpy

  • Chemist
  • Sr. Member
  • *
  • Mole Snacks: +219/-51
  • Offline Offline
  • Posts: 2628
Re: Base strength of hydrogen peroxide?
« Reply #5 on: April 19, 2018, 12:27:05 AM »

No. About every reaction, even the fastest combustions and deflagrations, happens through minority species.
Logged
Pages: [1]   Go Up
 

Mitch Andre Garcia's Chemical Forums 2003-Present.

Page created in 0.075 seconds with 24 queries.