Question

Find the total number of protons in 10 g of calcium carbonate.
A. $3.0115\times {{10}^{24}}$
B. $1.5057\times {{10}^{24}}$
C. $2.0478\times {{10}^{24}}$
D. $4.0956\times {{10}^{24}}$

Answer 1

Hint: As we know that calcium carbonate is called limestone. It has a chemical formula $CaC{{O}_{3}}$. We will find the number of moles in calcium carbonate by dividing given mass by molar mass.

Complete Solution :
- As we know that calcium carbonate is found to have the molar mass of 100g/mol.
It is found that in 10g of calcium carbonate, we will find the moles by dividing given mass by molar mass, then there will be:
$\dfrac{10g}{100g/mol}$
= 0.1 mol
- So, there will be 0.1 moles of calcium carbonate in this sample.
- As one mole of molecules is defined by $6.022\times {{10}^{23}}$ molecules. Therefore, 100 g of calcium carbonate contains $6.022\times {{10}^{22}}$ molecules.
- As we know that calcium carbonate contains one calcium atom, one carbon atom and three oxygen atoms.
- A carbon atom has six protons, a calcium atom has 20 protons and one oxygen atom has 8 protons. Therefore, three oxygen atoms will have $8 \times 3$ = 24 protons.
- In total, there are 50 protons and 50 electrons in one molecule of calcium carbonate. But we have molecules of calcium carbonate.
- The number of protons in 10 g = number of protons in $6.022\times {{10}^{22}}$ molecules. Therefore, in total we would have:
$\begin{align}
  & =50\times 6.022\times {{10}^{22}} \\
 & =3.0115\times {{10}^{24}} \\
\end{align}$
- Hence, we can conclude that the correct option is (a), that is the total number of protons in 10 g of calcium carbonate is $3.0115\times {{10}^{24}}$.
So, the correct answer is “Option A”.

Note: - As we know that atomic number is the number of protons that are present in the nucleus of an atom. The identity of an element is defined by the number of protons. For example, an element with six protons is a carbon atom, and it doesn’t matter how many neutrons are present.