Question

The molecular mass of $C{O_2}$ is 44amu and Avogadro’s number is $6.02 \times {10^{23}}$ . Therefore, the mass of one molecule of $C{O_2}$ 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: One mole of $C{O_2}$ contains $6.02 \times {10^{23}}$ molecules. So, we can calculate the mass of one molecule of $C{O_2}$ is $\dfrac{{Molecular\,mass\,of\,C{O_2}}}{{Anogadro's\,Number({N_A})}}$

Complete step by step answer:
The molecular mass of any molecule is the sum total of mass in grams of all the atoms that make up the molecule. It is measured in amu (atomic mass unit). So, we know that molecular mass of $C{O_2}$ is 44amu i.e. one mole of $C{O_2}$ has molecular mass of 44amu
We know,
Number of molecules = Number of moles $ \times $ Avogadro’s Number
And we have to find the mass of 1 molecule of compound, so
Molar mass of $C{O_2}$ = 44amu
1 mole of has $C{O_2}$ $6.02 \times {10^{23}}$ molecules
Hence, mass of $6.02 \times {10^{23}}$ molecule = 44amu
Therefore, Mass of one molecule of $C{O_2} = \dfrac{{Molecular\,mass\,of\,C{O_2}}}{{Anogadro's\,Number({N_A})}}$
Mass of one molecule of $C{O_2} = \dfrac{{44}}{{6.02 \times {{10}^{28}}}}$
 $ = 7.31 \times {10^{ - 23}}$
So, the mass of one molecule of $C{O_2}$ is $ = 7.31 \times {10^{ - 23}}$

Therefore, the correct answer is option (a).

Note: One carbon (atomic mass of C is 12) and two oxygen (atomic mass of each O is 16). Thus, the molecular mass of $C{O_2}$ is 44amu. A mole is the set of atoms or molecules. There are $6.02 \times {10^{23}}$ molecules of $C{O_2}$ in a mole.