Estimation of total iron in oxide ore comprises of three basic steps namely (i) extraction of iron into solution (ii) oxidation for volumetric analysis or precipitation for gravimetric analysis, and (iii) titration in volumetric analysis or ignition and weighting in gravimetric analysis. Which of the following concentrated acid is used for the first step i.e. extraction of iron into solution?
Combined carbon content in iron and steel is determined by treating the sample with dilute HNO3. So that combined carbon forms a soluble brown nitrated compound, the intensity of which is matched with that of a standard sample of similar composition treated under similar condition. The intensity of color produced is proportional to the carbon content of iron of steel sample. This method of combined carbon determination is called the
