How many grams of calcium oxide is obtained on heating 100 g of `CaCO_(3)(s)`?

Options

A. 50 g
B. 40 g
C. 56 g
D. 44 g

Answer

To determine how many grams of calcium oxide (CaO) are obtained from heating 100 grams of calcium carbonate (CaCO₃), we can follow these steps:

### Step 1: Write the decomposition reaction
When calcium carbonate is heated, it decomposes into calcium oxide and carbon dioxide:
\[ \text{CaCO}_3(s) \rightarrow \text{CaO}(s) + \text{CO}_2(g) \]

### Step 2: Determine the molar mass of CaCO₃
To find the molar mass of calcium carbonate (CaCO₃), we need to sum the atomic weights of its constituent elements:
- Calcium (Ca): 40 g/mol
- Carbon (C): 12 g/mol
- Oxygen (O): 16 g/mol (and there are 3 oxygen atoms)

Calculating the molar mass:
\[ \text{Molar mass of CaCO}_3 = 40 + 12 + (3 \times 16) = 40 + 12 + 48 = 100 \text{ g/mol} \]

### Step 3: Determine the molar mass of CaO
Next, we calculate the molar mass of calcium oxide (CaO):
- Calcium (Ca): 40 g/mol
- Oxygen (O): 16 g/mol

Calculating the molar mass:
\[ \text{Molar mass of CaO} = 40 + 16 = 56 \text{ g/mol} \]

### Step 4: Use stoichiometry to find the mass of CaO produced
From the balanced equation, we see that 1 mole of CaCO₃ produces 1 mole of CaO. Therefore, if we have 100 grams of CaCO₃, we can find out how many grams of CaO are produced.

Since 100 grams of CaCO₃ corresponds to 1 mole (as calculated above), we can directly relate this to the production of CaO:
- 1 mole of CaCO₃ produces 1 mole of CaO, which weighs 56 grams.

### Step 5: Conclusion
Thus, from 100 grams of CaCO₃, we will obtain:
\[ 56 \text{ grams of CaO} \]

### Final Answer:
The mass of calcium oxide obtained from heating 100 grams of calcium carbonate is **56 grams**.

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