A procedure15 for determining halogens in organic compounds uses an argentometric titration. To 50 mL of anhydrous ether is added a carefully weighed sample (10 - 100 mg) of unknown, plus 2 mL of sodium dispersion and 1 mL of methanol. (Sodium dispersion is finely divided solid sodium suspended in oil. With methanol, it makes sodium methoxide, CH3O- Na-, which attacks the organic compound, liberating halides.) Excess sodium is destroyed by slow addition of 2-propanol, after which 100 mL of water are added. (Sodium should not be treated directly with water because the H2 produced can explode in the presence of O2: 2Na + 2H2O → 2NaOH + H2.) This procedure gives a twophase mixture, with an ether layer floating on top of the aqueous layer that contains halide salts. The aqueous layer is adjusted to pH 4 and titrated with Ag, using the electrodes in Figure 26 11. How much 0.025 70 M AgNO3 solution will be required to reach each equivalence point when 82.67 mg of 1-bromo-4-chlorobutane (BrCH2CH2CH2CH2Cl; FM 171.46) are analyzed?