Question

The molar mass of $CaC{O_3}$ is:
A.$68g/mol$
B.$75g/mol$
C.$82g/mol$
D.$100g/mol$
E.$116g/mol$

Answer 1

In chemistry the molar mass of a chemical compound is obtained by dividing the mass of the sample of that particular compound by the amount of substance in that sample, measured in moles. The SI unit of molar mass is $kg/mol$.

Complete step by step answer:
Molar mass is often computed from standard atomic weights which is a terrestrial average and a function of a relative abundance of the isotopes of the constituent atoms on Earth. Molar mass is often used as an appropriate method for converting between the masses of a substance and the amount of substance for bulk quantities.
In order to calculate the molar mass of $CaC{O_3}$ we have to summate the individual molar mass of each element.
The individual molar masses are as follows:
$\begin{gathered} Ca - 40 \\\ C - 12 \\\ O - 16 \\\ \end{gathered}$
Since there are 3 moles of $O$, its molar mass is computed as $3 \times 16 = 48$.
Hence the molar mass of $CaC{O_3}$ $:40 + 12 + 48 = 100g/mol$.

So, Option D is the answer.

Additional Information:
The molar mass of elements is provided by the relative atomic mass of the element multiplied by the molar mass constant. One mole is equal to the number of atoms in $12g$ of carbon and this number is referred to as Avogadro number and its value is $6.022 \times {10^{23}}$ approximately. To convert from moles to atoms, multiply the molar amount by Avogadro number. In order to convert atoms to moles divide the atom amount by Avogadro number.

Note:
By multiplying the molar mass of the atoms by the number of atoms in each molecule the molar mass of the molecule is obtained. The units for molar mass are grams per mole or $g/mol$. The molar mass of a particular substance is the mass of one mole of substance.