the student then emptied the flask and dried it once again. to the empty flask she added pieces of a metal until the flask was about three-fourths full. she weighed the stoppered flask and its metal contents and found that the mass was 144.076 g. she then filled the flask with water, stoppered it, and obtained a total mass of 162.292 g for the flask, stopper, metal, and water. find the density of the metal. a. to find the density of the metal we need to know its mass and volume. we can easily obtain its mass by the method of differences: mass of metal = g − g =