To determine the number of neutrons in a substance, we need to know the atomic composition of the substance.
SO3 refers to the compound sulfur trioxide, which consists of one sulfur atom (S) and three oxygen atoms (O). The atomic mass of sulfur (S) is approximately 32.06 atomic mass units (amu), and the atomic mass of oxygen (O) is approximately 16.00 amu.
To calculate the number of moles of SO3 in 20 grams, we divide the given mass by the molar mass of SO3, which is the sum of the atomic masses of sulfur and oxygen multiplied by the number of atoms:
Molar mass of SO3 = (1 × atomic mass of S) + (3 × atomic mass of O) = (1 × 32.06 amu) + (3 × 16.00 amu) = 32.06 amu + 48.00 amu = 80.06 amu
Number of moles of SO3 = Mass of SO3 / Molar mass of SO3 = 20 g / 80.06 g/mol ≈ 0.2497 mol
Since one mole of a substance contains Avogadro's number (approximately 6.022 × 10^23) of particles, we can calculate the number of molecules (or atoms) in 0.2497 mol of SO3:
Number of molecules (or atoms) = Number of moles × Avogadro's number ≈ 0.2497 mol × 6.022 × 10^23/mol ≈ 1.503 × 10^23 molecules (or atoms)
However, the question asks for the number of neutrons in the given mass of SO3, not the total number of particles. To determine the number of neutrons, we need to know the isotopic composition of sulfur and oxygen in the sample, as isotopes have different numbers of neutrons. Without that information, it is not possible to provide an exact answer.