If 12.5 g of solid zinc carbonate is heated to constant mass, what is the mass of the substance formed ?
(Zn = 65, C = 12, O = 16).

Explanation

To solve the problem of determining the mass of the substance formed when 12.5 g of solid zinc carbonate (ZnCO3) is heated, we will follow these steps:

### Step 1: Write the decomposition reaction of zinc carbonate
When zinc carbonate is heated, it decomposes into zinc oxide and carbon dioxide. The balanced chemical equation for this reaction is:
\[ \text{ZnCO}_3 (s) \rightarrow \text{ZnO} (s) + \text{CO}_2 (g) \]

### Step 2: Calculate the molar mass of zinc carbonate (ZnCO3)
To find the molar mass of ZnCO3, we add the atomic masses of its constituent elements:
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