Question

Calculate the molar mass of the following:
(1) ${{H}_ {2}} O$
(2) $C{{O}_ {2}} $
(3) $C{{H}_ {4}} $

Answer 1

Hint: To solve this question find the molecular mass of the individual atom of each of the compound and then add all the atomic weights together, and we would get the molar mass.

Complete answer:
We have been provided with three compounds: ${{H}_ {2}} O$, $C{{O}_ {2}} $ and $C{{H}_ {4}} $,
We need to find the molar mass of these three compounds,
So, for that:
We know that the molar mass of a compound is the mass of a substance divided by the amount of substance in that sample which is measured in moles.
The first compound is ${{H}_ {2}} O$ that is water,
So, we know that the molar mass of hydrogen is 1 g/mol and oxygen is 16 g/mol,
So, the molar mass of ${{H}_ {2}} O$ would be: $(2\times 1) +16=18g/mol$,
The next compound that we have is $C{{O}_ {2}} $ that is carbon dioxide,
So, we know that the molar mass of carbon is 12 g/mol and oxygen is 16 g/mol,
So, the molar mass of $C{{O}_ {2}} $ would be: $12+(16\times 2) =44g/mol$,
The last compound that we have is $C{{H}_ {4}} $ that is methane,
So, we know that the molar mass of carbon is 12 g/mol and hydrogen is 1 g/mol,
So, the molar mass of $C{{H}_ {4}} $ would be: $12+(1\times 4) =16g/mol$,
So, we have found the molar mass of all the three compounds,
For ${{H}_ {2}} O$ it comes out to be: 18 g/mol
For $C{{O}_ {2}} $ it comes out to be: 44 g/mol
And for $C{{H}_ {4}} $ it comes out to be: 16 g/mol

Note:
There is a difference between the molar mass and molecular mass, molar mass is the mass of a mole of substance and molecular mass is the mass of the molecules.