Question

Aspirin has the formula ${C_9}{H_8}{O_4}$ ​. How many atoms of oxygen are there in a tablet weighing $360mg$ ?
A. $1.204 \times {10^{23}}$
B. $1.08 \times {10^{22}}$
C. $1.204 \times {10^{24}}$
D. $4.81 \times {10^{21}}$

Answer 1

Hint: In this question we will be learning how to calculate the weight of a particular compound on the tablet. To calculate the number of atoms involved in the tablet we will use the concept of moles.Mole, likewise spelled mol, in science, a standard logical unit for estimating enormous amounts of little elements, for example, ions, atoms, or other specified particles.
The mole was previously characterized as the quantity of particles decided experimentally to be found in 12 grams of carbon-12. The number of units in a mole likewise bears the name Avogadro's number.

Complete step by step answer:
Let us write the given parameters first and calculate the weight of the aspirin molecule
${C_9}{H_8}{O_4} \Rightarrow 9 \times 12 + 8 \times 1 + 16 \times 4$
That is;
${C_9}{H_8}{O_4} \Rightarrow 180$
Therefore, the weight of the aspirin molecule is 180.
Now, let’s calculate the number of moles;
Mole = $\dfrac{{given.mass}}{{molecular.weight}}$
$mole = \dfrac{{360 \times {{10}^{ - 3}}}}{{180}}$
By further simplification we get the value of mole as:
$mole = 2 \times {10^{ - 3}}$
We also know that the value of $1mole$is:
$1mole = {N_A}(6 \times {10^{23}})$.
So, let us now calculate the number of Oxygen atoms;
$ \Rightarrow $Number of oxygen atoms = $4 \times 2 \times {10^{ - 3}}{N_A}$
As we know the value of ${N_A}$ let us substitute the value in the above equation:
$ \Rightarrow $Number of oxygen atom = $4 \times 2 \times {10^{ - 3}} \times 6 \times {10^{23}}$ = $4.81 \times {10^{21}}$
$ \Rightarrow $Number of Oxygen atoms = $4.81 \times {10^{21}}$.

So the answer is option D.

Note: The mole was previously characterized as the quantity of particles decided experimentally to be found in 12 grams of carbon-12. The number of units in a mole likewise bears the name Avogadro's number,
To solve this question, one needs to know how to calculate the number of moles of an individual particle from a compound. One needs to know the concept of mole and molar mass to solve the problem and some basic concepts of chemistry.