2023 Some Basic Concepts of ChemistryStoichiometry and Percentage Purity Medium Question 1 of 2 in Stoichiometry and Percentage Purity

The right option for the mass of $CO_2$ produced by heating 20 g of 20% pure limestone is (Atomic mass of $Ca=40$): $CaCO_3\xrightarrow{1200\ K}CaO+CO_2$

A 1.32 g
B 1.12 g
C 1.76 g
D 2.64 g

The answer is C.

Solution

20 g of 20% pure $CaCO_3$ is 4 g; $\frac{4\times44}{100}=1.76$ g of $CO_2$.

20 g of 20% $CaCO_3=20\times\frac{20}{100}=4\ g\ CaCO_3$ $\underset{100\ g}{CaCO_3}\xrightarrow{1200\ K}CaO+\underset{44\ g}{CO_2}$ According to the reaction, 100 g of $CaCO_3\rightarrow$ 44 g of $CO_2$ 4 g $CaCO_3\rightarrow\frac{4\times44}{100}$ g of $CO_2=1.76$ g of $CO_2$

Concept mass of CO2 from impure limestone

Stoichiometry and Percentage Purity in past papers

2 questions from this chapter have appeared across 2 exam years.