Question

The relative formula mass, Mr, of calcium carbonate, CaCO3, is 100.

What is the mass of carbon present in 100g of calcium carbonate?

Answer 1

12 grams

Step-by-step explanation:

The relative formula mass (Mr) of calcium carbonate (CaCO3) is the sum of the atomic masses of its constituent elements. The atomic mass of carbon (C) is approximately 12.01 g/mol.

For calcium carbonate (CaCO3):

`\[ Mr = (atomic\ mass\ of\ Ca) + (atomic\ mass\ of\ C) + 3 * (atomic\ mass\ of\ O) \]`

Given that Mr is 100, we can set up the equation:

`\[ 100 = (atomic\ mass\ of\ Ca) + 12.01 + 3 * (16) \]`

Now, solve for the atomic mass of calcium (Ca):

`\[ atomic\ mass\ of\ Ca = 100 - 12.01 - 3 * 16 \]`

`\[ atomic\ mass\ of\ Ca = 100 - 12.01 - 48 \]`

`\[ atomic\ mass\ of\ Ca = 39.99 \]`

Now, to find the mass of carbon in 100g of calcium carbonate, we consider the ratio of the atomic mass of carbon to the Mr of calcium carbonate.

The mass of carbon =
`\( (atomic\ mass\ of\ C)/(Mr) * 100g \)\[ (12.01)/(100) * 100g = 12g \]`

Therefore, the mass of carbon present in 100g of calcium carbonate is approximately 12 grams.