Question

What is the percentage of calcium in calcium carbonate\[\left( {{\rm{CaC}}{{\rm{O}}_{\rm{3}}}} \right)\]?
A. \[40\]
B. \[12\]
C. \[20\]
D. \[48\]

Answer 1

Hint: we know that the molecular mass can be found by adding the atomic mass of each element present in the molecule. The mass percentage of an element in a compound can be calculated from the molar masses of the element and the compound.

Complete step by step answer:
\[{\rm{CaC}}{{\rm{O}}_{\rm{3}}}\] is a white, odorless powder or colourless crystals. It is insoluble in water. It is an ionic compound. It can be written as a compound made up of doubly ionized calcium ions and a radical called carbonate.

Calcium carbonate is the principal constituent of limestone. It creates a substance that is used to bind the material, called quicklime. It is a caustic material and when water is mixed in it then it forms heat. When calcium chloride is reacted with sodium carbonate, it produces sodium chloride and calcium carbonate.

Here, first we have to find the molecular mass of \[\left( {{\rm{CaC}}{{\rm{O}}_{\rm{3}}}} \right)\], when we add mass of calcium, mass of oxygen and mass of carbon then the addition of total amount is the molecular mass of calcium carbonate \[\left( {{\rm{CaC}}{{\rm{O}}_{\rm{3}}}} \right)\].
\[
{\rm{Mass}}\;{\rm{of}}\;{\rm{CaC}}{{\rm{O}}_3} = {\rm{mass}}\;{\rm{of}}\;{\rm{C}} + 3 \times {\rm{mass}}\;{\rm{of}}\;{\rm{O}} + {\rm{mass}}\;{\rm{of}}\,{\rm{Ca}}\\
 = 12 + 48 + 40\\
 = 100\;{\rm{amu}}
\]
We know that mass of calcium in one mole of \[{\rm{CaC}}{{\rm{O}}_{\rm{3}}}\] is \[{\rm{40}}\;{\rm{gram}}\].
Then, the percentage of calcium is calculated as shown below.
\[
{\rm{Percentage of calcium}} = \dfrac{{40}}{{100}} \times 100\\
 = 40\;\%
\]

Therefore, the correct option is option (A).

Note: The major part of calcium carbonate is found in extraction of mining. Pure calcium carbonate is produced by pure marvel. It is used in medication to treat symptoms caused by too much stomach acid such as heartburn, upset stomach or indigestion. It is an antacid that works by lowering the amount of acid in the stomach.