Question

Problems: 1. A student adds 25 drops of cetyl alcohol in hexane, (solution concentration 1.08 x I0 g/mL) to form a monolayer of the alcohol on the surface of water in a Petri dish with an 4 area of 241 cm2 The cetyl alcohol molecules are cylindrical with the diameter of the cylinder equal to one fifth of the length. Assume the long axis of the cylinder is perpendicular to the water surface. The medicine dropper used in this experiment was calibrated at 81 drops per milliliter. Using the above data and model, calculate Avogadro's number. (Hint: the volume of a cylinder is v-arh, r radius, h height and r- /I0.) 2. Prior to 1961, the molar atomic mass of the oxygen-16 isotope was taken as exactly 16 g/mol by physicists. Chemists actually used a different value. In 1961 the molar atomic mass of carbon 12 was defined to be exactly 12 g/mol (a value agreed upon by chemists and physicists) and the molar atomic masses of all the elements were re-evaluated according to this new standard. This made the re-evaluated molar mass of oxygen-16 become 15.994915 g/mol. Avogadro's number is defined as the number of atoms in the molar atomic mass of an element. The present accepted value for Avogadro's number is 6.0221367 x 10 /mol. What was the value of Avogadro's number used by physicists before 1961? 72
plz both with explanation

Answer 1