Question

The molecular mass of ${ CO }_{ 2 }$ is 44 amu and the Avogadro number is $6.02\times 10^{ 23 }$. Therefore, the mass of one molecule of ${ CO }_{ 2 }$ is:
A. $7.31\times 10^{ -23 }$
B. $3.65\times 10^{ -23 }$
C. $1.01\times 10^{ -23 }$
D. $2.01\times 10^{ -23 }$

Answer 1

Hint: You can understand this question that we have the weight of $6.02\times 10^{ 23 }$ (1 mole) ${ CO }_{ 2 }$ molecules is equal to 44 g. So, you just need to find out the mass of one molecule. Now try to solve it.

Complete step by step answer:

We are given molecular mass of ${ CO }_{ 2 }$ = 44 amu
Avogadro number = $6.02\times 10^{ 23 }$
We know that the Avogadro number is equal to 1 mole.
And, the molecular mass of ${ CO }_{ 2 }$ is also equal to 1 mole of ${ CO }_{ 2 }$ molecule.
Hence, we can write,
$Mass\quad of\quad one\quad molecule\quad of\quad CO_{ 2 }\quad =\quad \dfrac { Mass\quad of\quad 1\quad mole\quad molecules\quad of\quad CO_{ 2 } }{ Avogadro\quad Number }$

$Mass\quad of\quad one\quad molecule\quad of\quad CO_{ 2 }\quad =\quad \dfrac { 44 }{ 6.02\times { 10 }^{ 23 } }$
$Mass\quad of\quad one\quad molecule\quad of\quad CO_{ 2 }\quad =\quad 7.31\times { 10 }^{ -23 }$

Therefore, we can conclude that the correct answer to this question is option A.

Additional information:
We should know that Carbon dioxide is a colorless gas with a density of about 60% higher than that of dry air. It consists of a carbon atom covalently double bonded to two oxygen atoms. It occurs naturally in Earth's atmosphere as a trace gas.

Note: We should know that the molecular mass is the mass of a given molecule. It is measured in daltons (Da or amu).
Also, different molecules of the same compound may have different molecular masses because they contain different isotopes of an element.