Question

What is the molar mass of K?

Answer 1

Hint: One mole of a substance is the molar mass. Do not confuse between molecular weight and the molar mass, they both are not the same. It is easy to calculate the molar mass of an atom, just multiply the number of atoms in that particular element by its atomic mass. For potassium, the atomic mass is $39.0983$ amu.

Complete answer:
The molar mass of an atom is defined as the mass of a sample of that compound divided by the amount of substance in that sample, measured in moles. It is also the mass of a given element or molecule per mole of that substance. The unit of molar mass is gram per mole.
The molar mass of an element is calculated as, number of atoms of the element multiplied by the atomic mass. In the case of potassium (K), the number of atoms of potassium is $1$ and its atomic mass is $39.0983$ . And so the molar mass of potassium is:
Number of atoms of potassium multiplied by its atomic mass $=1\times 39.0983$
Therefore the molar mass of potassium (K) is $39.0983{\displaystyle \frac{g}{mol}}$
The molar mass is an intensive property of the substance that does not depend on the size of the sample.
 To calculate the molar mass of the compounds: first, identify the molecular formula of each element in the compound. Then determine the number of atoms of each element. Next, multiply the atomic mass by the number of atoms for each element. Lastly, add the molar masses of each element to get the molar mass of the compound.

Note:
Molar mass and molecular weight are slightly different from each other. Molar mass is one mole of a particular substance whereas the molecular weight is the mass of a molecule. Molecular weight is unitless but is given as AMU (atomic mass unit). It is calculated as the mass of a substance relative to the ${\displaystyle \frac{1}{{12}^{th}}}$ of the mass of carbon $-12$ atom.