A 25.00-mL volume of commercial hydrogen peroxide solution was diluted to 250.0 mL in a volumetric flask. Then 25.00 mL of the diluted solution were mixed with 200 mL of water and 20 mL of 3 M H₂SO₄ and titrated with 0.021 23 M KMnO₄. The first pink color was observed with 27.66 mL of titrant. A blank prepared from water in place of H₂O₂ required 0.04 mL to give visible pink color. Using the H₂O₂ reaction in Table 15-3, find the molarity of the commercial H₂O₂.

Table 15-3

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TABLE 15-3 Analytical applications of permanganate titrations Species analyzed Oxidation reaction Notes Fe* = Fe* + e Fe* is reduced to Fe* with Sn2 or a Jones reductor. Titration is carried out in 1 M H,SO, or 1 M HCI containing Mn*, H,PO, and H,SO,. Mn" inhibits oxidation of CI by MnO,. H,PO, complexes Fe to prevent formation of yellow Fe"-chloride complexes. Add 95% of titrant at 25°C, then complete titration at 55°-60°C. Fe H;C-0. H,C0, = 200, + 2H* + 2e Br Br = Br(g) + e Titrate in boiling 2 M H,SO, to remove Br,(g). H,O, = HNO, + H,0 = NO, + 3H* + 2e Titrate in 1 M H,SO, Add excess standard KMNO, and back-titrate after 15 min at 40°C with Fe2*. H,O, 0,(g) + 2H* + 2e HNO, As Sh = HASO, + 2H* + 2e H;SbO, + H,0 = H,SbO, + 2H* + 2e Mo + 2H,0 = MoO; + 4H* + 3e H,AsO, + H;0 Titrate in 1 M HCI with KI or ICl catalyst. Titrate in 2 M HCI. Reduce Mo in a Jones reductor, and run the Mot into excess Fe* in 1 M H,SO,. Titrate the Fe+ formed. Reduce W with Pb(Hg) at 50°C and titrate in I M HCI. Reduce U to U with a Jones reductor. Expose to air to produce U**, which is titrated in 1 M H,So. Reduce Ti to Ti* with a Jones reductor, and run the T*into excess Fe* in 1 M H,SO,. Titrate the Fe* Mo w* + 2H,0 = wo* + 4H + 3e U* + 2H,0 = UO* + 4H* + 2e Ti* + H,0 = Tio* + 2H* +e that is formed. Mg". Ca, Sr Zn La, Th, Ph Ce", Bio", Ag H,C,O, = 2C0, + 2H + 2e Precipitate the metal oxalate. Dissolve in acid and titrate the H;C,0. Ва Peroxydisulfate is added to excess standard Fe* containing H,PO, Unreacted Fe2 is titrated with Mno.. so; + 2Fe* + 2H* = 2Fe* + 2HSO, PO Mo + 2H;O (NH,),PO, - 12M00, is precipitated and dissolved in H,SO. The Mo(VI) is reduced (as above) and titrated. MoO* + 4H* + 3e