Question

How many grams are contained in 0.644 mol oxygen?

a. 10.3 g
b. 20.6 g
C. 0.0201 g
d. 0.0403 g
e. 0.644 g

Answer 1

To find the mass of 0.644 mol of oxygen, we multiply the number of moles by the molar mass of oxygen gas (O₂), which is 32.00 g/mol, resulting in 20.608 g. This value rounds to 20.6 g, which is option b.

Step-by-step explanation:

To determine the mass of 0.644 mol of oxygen, we must use the molar mass of oxygen. The molar mass of elemental oxygen (O) is approximately 16.00 g/mol. However, oxygen typically exists as a diatomic molecule (O₂), so its molar mass is approximately 32.00 g/mol.

Calculation steps:

1. Identify the molar mass of oxygen gas (O₂), which is 32.00 g/mol.
2. Multiply the given number of moles by the molar mass:
   0.644 mol × 32.00 g/mol = 20.608 g of O₂.

Therefore, the mass contained in 0.644 mol of oxygen is 20.608 g, which can be rounded to 20.6 g, corresponding to option b.