To my surprise, last night I learned from a chemist friend that mixing hydrogen peroxide with (sodium hypochlorite) bleach liberates oxygen, presumably from the decomposition of both substances, leaving water and sodium chloride as well as the oxygen gas. How much oxygen should it liberate?
In addition to weight percentages (3% being the usual article of commerce in pharmacies) H₂O₂ is commonly sold by "volumes": "20 volumes" yields 20 mℓ of O₂ gas from the decomposition of the H₂O₂ in 1 mℓ of the solution. O₂'s molecules weigh 32 daltons, so a mole of it weighs 32 g; two moles of H₂O₂ are needed to produce one mole of O₂, and they will weigh 34 g each, 68 g in total. The combined gas law is that PV = nRT, where [R ≈ 8.3144598 kPa ℓ / mol / K] is the universal gas constant, so at 20° = 293.15 K a mole of an ideal gas at 101.325 kPa would occupy 8.3144598 × 293.15 / 101.325 ≈ 24.055 ℓ. The density of pure H₂O₂ is 1.450 g/cc, thus 21.32 mmol of O₂ per cc, which gives 512.85 cc of O₂ gas per cc of H₂O₂, so pure hydrogen peroxide would be "512.85 volumes". So "20 volumes" H₂O₂ is only about 3.900% by weight. (But Dr. Google says it's actually 6%, so my calculations must be off.)
The common bleaches sold here are 57 g Cl/ℓ and 25 g Cl/ℓ. Sodium hypochlorite is NaClO, with one atom of oxygen per atom of chlorine. ...