Question

What is the molar mass of $HCN$ ?

Answer 1

The molar mass of the compound is the sum of the atomic mass of all the constituent atoms. Here we have $HCN$ , thus we will find the algebraic sum of the atomic mass of hydrogen, carbon and nitrogen. The molar mass of $HCN$ is mass for one mole of $HCN$ .

Complete Step By Step Answer:
The molar mass of the compound may be defined as the sum of the all atomic mass of the atoms of the compound. Therefore to calculate the molar mass of $HCN$ we will find the algebraic sum of the atomic mass of the hydrogen, carbon and nitrogen. We know that atomic mass of hydrogen is $1{\text{ }}amu$ while mass of carbon atom is $12{\text{ }}amu$ and mass of nitrogen atom is $14{\text{ }}amu$ . Thus we can find the molar mass of the compound as:
$\Rightarrow 1{\text{ }}amu{\text{ }} + {\text{ }}12{\text{ }}amu{\text{ }} + {\text{ }}14{\text{ }}amu$
$\Rightarrow 27{\text{ g mo}}{{\text{l}}^{ - 1}}$
Thus we can say that the molar mass of $HCN$ is $27{\text{ g mo}}{{\text{l}}^{ - 1}}$ . The units of atomic mass and molar mass are different. The molar mass is calculated for one mole of the substance while atomic mass is calculated for one atom of the element.

Note:
It must be noted that the atomic mass which is used above is not accurate mass. After decimal place the answer may vary. The molar mass is the mass for one mole of substance and hence it is calculated grams per mole. The atomic mass is calculated as $amu$ which stands for atomic mass unit. $HCN$ is also known as hydrogen cyanide which is poisonous in nature. Small consumption of hydrogen cyanide can lead to death of living organisms.