How many oxygen atoms are in 3.90 g of quartz?

To find the number of oxygen atoms in 3.90 g of quartz, you will need to go through the following steps:

Step 1: Determine the molecular formula of quartz.
Quartz's molecular formula is SiO2. This means that each molecule of quartz contains one silicon atom (Si) and two oxygen atoms (O).

Step 2: Calculate the molar mass of quartz.
To calculate the molar mass, you need to add up the atomic masses of all the atoms in the molecular formula. The atomic masses of silicon (Si) and oxygen (O) are approximately 28.09 g/mol and 16.00 g/mol, respectively.

Molar mass of SiO2 = (1 × atomic mass of Si) + (2 × atomic mass of O)
= (1 × 28.09 g/mol) + (2 × 16.00 g/mol)
≈ 60.09 g/mol

Step 3: Determine the number of moles of quartz.
To find the number of moles, divide the given mass by the molar mass.

Number of moles = mass of quartz / molar mass of quartz
= 3.90 g / 60.09 g/mol
≈ 0.0649 mol

Step 4: Calculate the number of oxygen atoms.
Since quartz contains two oxygen atoms (O) per molecule (SiO2), the number of oxygen atoms can be calculated by multiplying the number of moles of quartz by Avogadro's number (6.022 × 10^23 atoms/mol).

Number of oxygen atoms = number of moles of quartz × Avogadro's number
≈ 0.0649 mol × 6.022 × 10^23 atoms/mol
≈ 3.92 × 10^22 atoms

Therefore, there are approximately 3.92 × 10^22 oxygen atoms in 3.90 g of quartz.