Question

The molar mass of $\text{CaC}{{\text{O}}_{\text{3}}}$ is:
a.) $\text{68 g/mol}$
b.) $\text{75 g/mol}$
c.) $\text{82 g/mol}$
d.) $\text{100 g/mol}$
e.) $\text{116 g/mol}$

Answer 1

Hint: To know the molar mass of $\text{CaC}{{\text{O}}_{\text{3}}}$ we need to know the formula, the number of atoms of each element present in the compound. These two values will help us to get the molar mass of $\text{CaC}{{\text{O}}_{\text{3}}}$.

Complete step-by-step answer:
We know that molar mass is also known as molecular weight. By molecular weight we mean the mass of the whole molecule.
First, we know that the chemical formula of Calcium Carbonate is $\text{CaC}{{\text{O}}_{\text{3}}}$.
As we already know,
Mass of Calcium is 40.
Mass of Carbon is 12.
Mass of Oxygen is 16.

Now multiplying the mass of each element by the number of atoms of that element. This will result as:

$40\times 1$, since there is one atom of calcium in the compound.
$12\times 1$, since there is one atom of carbon in the compound.
$16\times 3$, since there are 3 atoms of oxygen in the compound.

Now, adding all the masses obtained after the multiplication. We get that,
$\begin{align}
  & (1\times 40)\text{ }+\text{ (}1\times 12)\text{ }+\text{ (}3\times 16) \\
 & =\text{ 40 + 12 + 48} \\
 & \text{= 100} \\
\end{align}$
So we can say that the molar mass of $\text{CaC}{{\text{O}}_{\text{3}}}$ is $\text{100 g/mol}$. So the correct option is Option D.

Note: In chemistry, the molar mass of a chemical compound is defined as the mass of a sample of that compound divided by the amount of the substance in that sample which is measured in moles. The molar mass is a bulk not molecular property of a substance.