Question

How many moles of marble, CaCO₃, are there in a 275 g piece of marble?

A. 4.57 x 10⁻²²
B. 0.364
C. 2.75
D. 275

Answer 1

The number of moles of CaCO₃ in a 275 g piece of marble is calculated using the molar mass of CaCO₃, which is 100 g/mol. By dividing the mass by the molar mass, we find that there are 2.75 moles of CaCO₃, making the correct answer C. 2.75.

Step-by-step explanation:

To calculate the number of moles of marble (CaCO₃) in a 275 g piece of marble, we need the molar mass of CaCO₃. The molar mass is the sum of the atomic masses of calcium (Ca), carbon (C), and three oxygen (O) atoms. Calcium has an atomic mass of approximately 40 g/mol, carbon approximately 12 g/mol, and oxygen approximately 16 g/mol. Therefore, the molar mass of CaCO₃ is:

(40 g/mol Ca) + (12 g/mol C) + (3 × 16 g/mol O) = 100 g/mol CaCO₃

Now, using the formula:

Number of moles = mass (g) ÷ molar mass (g/mol)

We get:

Number of moles of CaCO₃ = 275 g ÷ 100 g/mol = 2.75 mol

Therefore, the correct answer is C. 2.75 moles of marble.