Calculate the mass fraction of NH4Cl in a 12.5 g sample if this sample is diluted with water in a 100 ml volumetric flask. Titration of an aliquot portion of a solution of this substance with a volume of 5.0 ml consumed 7.34 ml of NaOH titrant (c1/zT) = 0.05 mol/l. Write: a) reaction scheme; b) factors of equivalence of participants of reaction; c) the expression of the law of equivalents for this reaction; d) type of chemical reaction (titration method); e) indicator for determination of equivalence point (choice to explac)