Question

Calculate the molecular mass of\[C{{H}_{3}}OH\] .
(A) 29
(B) 30
(C) 32
(D) 28

Answer 1

Hint: For calculating the molecular mass we have to add the atomic mass of each atom in the molecule. We should know about the atomic mass of each atom.

Step by step solution:
The sum of the atomic masses of all atoms in a molecule, based on a scale in which the atomic masses of hydrogen, carbon, nitrogen, and oxygen are 1, 12, 14, and 16, respectively. To calculate the molar mass of a molecule, we first obtain the atomic weights from the individual elements in a periodic table. We then count the number of atoms and multiply it by the individual atomic masses.
Atomic masses are the sum of neutrons and protons and multiply them by 1 amu.
For calculation the molecular mass of \[C{{H}_{3}}OH\]:
Atomic mass of carbon(C): 12
Atomic mass of hydrogen (H): 1 (hydrogen has only electrons)
Atomic mass of oxygen (O): 16
So, the molecular mass of \[C{{H}_{3}}OH\]is = 1 x atomic mass of carbon + 4 x (atomic mass of hydrogen) + 1 x (atomic mass of oxygen)
Molecular mass of \[C{{H}_{3}}OH\]is = 1 x (12) + 4 x (1) + 1 x (16)
Molecular mass of \[C{{H}_{3}}OH\]is = 32
So, the correct answer is option “C”.

Note: Unit of molecular mass is kg / mol or g/mol. The amu is the unit of atomic mass which is 1/12 of the mass of an unbound neutral atom. One AMU is the average of the proton rest mass and the neutron rest mass.