If 10 lb of H₂CO₃ is used, how many pounds of CaCO₃ will react?

• A. 10 lb
• B. 16.1 lb
• C. 20 lb
• D. 25 lb

Answer: (B)

To understand the relationship between H₂CO₃ (carbonic acid) and CaCO₃ (calcium carbonate), it is important to recognize the stoichiometry of the reaction between these two substances. When carbonic acid reacts with calcium carbonate, the reaction can be represented as follows:

[ \text{H}_2\text{CO}_3 + \text{CaCO}_3 \rightarrow \text{Ca}^{2+} + 2\text{HCO}_3^{-} ]

In this reaction, one mole of carbonic acid reacts with one mole of calcium carbonate. The molecular weights of H₂CO₃ and CaCO₃ are crucial for determining how much CaCO₃ is needed to react with a certain amount of H₂CO₃.

The molecular weight of H₂CO₃ is approximately 100 g/mol, and the molecular weight of CaCO₃ is approximately 100 g/mol as well. Therefore, the molar ratio is 1:1 in terms of the number of moles reacting.

To calculate how many pounds of CaCO₃ will react with 10 lb of H₂CO₃, consider the molar weight as follows:

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