Calculate a) the molecular weight of the substance HNO3 b) the mass fraction of oxygen (w) in this substance

a) molecular weight of HNO3:
H = 1 g / mol;
N = 14 g / mol;
O = 16 g / mol, and since we have 3 oxygen atoms, we should 16 * 3 = 48 g / mol
Now add 1 + 14 + 48 = 63 g / mol.
Answer: 63 g / mol
b) mass fraction of oxygen in nitric acid:
The mass fraction can be calculated using the formula: A * n * 100 / M = w, where A is the atomic mass of the element, n is the number of atoms, M is the molecular weight of the substance. Now we substitute 16 * 3 * 100/63 = 76% into the formula
Answer: 76%