Question

Calculate the molecular mass of $C{{H}_{3}}OH$.
A. 29
B. 30
C. 32
D. 28

Answer 1

Hint: As we know that the molecular mass of any compound is basically equal to the sum of the atomic masses of all the elements times their respective number of atoms. To solve this question, we should know the atomic masses of carbon, hydrogen and oxygen.

Complete step by step answer:
- As we know that gram molecular mass is the mass of one mole of a molecular compound. We can say that it is numerically equal to the molecular weight. In order to find the molecular weight, we need to find the individual atomic mass of each of the atoms present.
- We should know the individual atomic masses of each atom present that are carbon, hydrogen and oxygen. We can know from the periodic table that atomic mass of carbon = 12 grams, atomic mass of oxygen = 16 grams, atomic mass of hydrogen = 1 grams.
- Hence, we can calculate the molecular mass of $C{{H}_{3}}OH$ as:
$\begin{align}
 & C{{H}_{3}}OH \\
 & =\left( 1\times 12 \right)+\left( 4\times 1 \right)+\left( 1\times 16 \right) \\
 & =12 + 4 + 16 \\
 & =32 g \\
\end{align}$
- Hence, we can conclude that the correct option is (c), that is the molecular mass of $C{{H}_{3}}OH$ is 32 So the correct answer is “C”:

Note: - We should note that molar mass numerically is the same as gram molecular mass. The main difference in between these is that gram molecular mass specifies the mass unit to be used. Let’s consider an example of molecular mass of nitrogen is 28, so the gram molecular mass of nitrogen is 28 g.