Number of Oxygen Molecules in 100 grams of Limestone

Limestone is a sedimentary rock primarily composed of calcium carbonate (CaCO3). It is formed from the remains of marine organisms over millions of years. In order to determine the number of oxygen molecules present in 100 grams of limestone, we need to understand the chemical composition of limestone and calculate the number of moles of oxygen.

Chemical Composition of Limestone

Limestone is composed of calcium carbonate (CaCO3) along with impurities such as magnesium carbonate (MgCO3), iron carbonate (FeCO3), and other minerals. The molecular formula of calcium carbonate indicates that it consists of one calcium atom (Ca), one carbon atom (C), and three oxygen atoms (O).

Calculating the Moles of Oxygen

To calculate the number of moles of oxygen in 100 grams of limestone, we need to follow these steps:

1. Determine the molar mass of calcium carbonate (CaCO3).
- The atomic masses of calcium (Ca), carbon (C), and oxygen (O) are approximately 40, 12, and 16 grams per mole, respectively.
- The molar mass of calcium carbonate is calculated as follows:
Molar mass = (1 × atomic mass of Ca) + (1 × atomic mass of C) + (3 × atomic mass of O)

2. Calculate the number of moles of calcium carbonate in 100 grams of limestone.
- This can be done using the formula:
Moles = Mass (in grams) / Molar mass (in grams per mole)

3. Determine the number of moles of oxygen.
- Since there are three oxygen atoms in one molecule of calcium carbonate, the number of moles of oxygen is three times the number of moles of calcium carbonate.

4. Convert the number of moles of oxygen to molecules.
- One mole of any substance contains Avogadro's number (6.022 × 10^23) of molecules. Therefore, the number of oxygen molecules can be calculated by multiplying the number of moles of oxygen by Avogadro's number.

Final Calculation

By following the above steps, we can calculate the number of oxygen molecules in 100 grams of limestone. The final answer will depend on the exact composition of the limestone sample, as impurities may vary. However, the general approach outlined above can be used to estimate the number of oxygen molecules present.