Question

What weight of $CaC{O_3}$ must be decomposed to produce the sufficient quantity of carbon dioxide to convert $21.2kg$ of $N{a_2}C{O_3}$ completely into $NaHC{O_3}$?
[Atomic mass $Na = 23$ ,$Ca = 40$]
$CaC{O_3} \to CaO + C{O_2}$
$N{a_2}C{O_3} + C{O_2} + {H_2}O \to 2NaHC{O_3}$
A. $100kg$
B. $20kg$
C. $120kg$
D. $30kg$

Answer 1

Hint: A chemical reaction in which one reactant breaks down into two or more products is known as a decomposition reaction.

Complete answer:
$CaC{O_3} \to CaO + C{O_2}$
The molecular masses of the above reactants and products is:
$100 \to 56 + 44$
$N{a_2}C{O_3} + C{O_2} + {H_2}O \to 2NaHC{O_3}$
The molecular masses of the above reactants and products are:
$106 + 44 + 18 \to 107$
So, we have $21.2kg$ of $N{a_2}C{O_3}$$ = 21200g$ of $N{a_2}C{O_3}$
The amount of $C{O_2}$ needed $ = 21200 \times \dfrac{{44}}{{106}}$
The amount of $C{O_2}$ needed$ = 8.8kg$
$8.8kg$ of $C{O_2}$ $ = 8800g$
As we the amount of $C{O_2}$ needed we can calculate the amount of $CaC{O_3}$ needed,
Amount of $CaC{O_3}$ needed $ = \dfrac{{8800 \times 100}}{{44}}$
Amount of $CaC{O_3}$ needed $ = 20000g$
Amount of $CaC{O_3}$ needed $ = 20kg$

So, the correct answer is “Option B”.

Note:
A source of energy, such as heat, light, or electricity, is required for most breakdown reactions. Even if one or more of the products are still compounds, a reaction is termed a decomposition reaction. A metal carbonate decomposes into a metal oxide and carbon dioxide gas when exposed to air.