Final answer:
To find the number of oxygen molecules in the solution, calculate the number of moles of nitric acid and water and use the mole ratio to find the number of oxygen molecules. The solution contains approximately 1.51 x 10^22 oxygen molecules.
Step-by-step explanation:
To find the number of oxygen molecules present in the solution, we need to first calculate the number of moles of nitric acid and water. We can then use the mole ratio between nitric acid and oxygen molecules to find the number of oxygen molecules.
Given that the concentration of nitric acid is 68.0% by mass, we can calculate its moles by dividing the mass of nitric acid by its molar mass. The molar mass of nitric acid (HNO3) is 63.01 g/mol. Therefore, the number of moles of nitric acid is 6.3 g / 63.01 g/mol = 0.1 mol.
The number of moles of water can be calculated in a similar way. The molar mass of water (H2O) is 18.02 g/mol. Therefore, the number of moles of water is 68 g / 18.02 g/mol = 3.77 mol.
From the balanced chemical equation, we know that 4 moles of nitric acid react with 1 mole of oxygen molecules to produce 4 moles of nitric acid. Therefore, the number of oxygen molecules present in the solution can be calculated as:
(0.1 mol nitric acid) * (1 mol oxygen molecules / 4 mol nitric acid) = 0.025 mol oxygen molecules.
Finally, we can convert the number of moles of oxygen molecules to the number of molecules by multiplying by Avogadro's number (6.022 x 10^23 molecules/mol):
(0.025 mol oxygen molecules) * (6.022 x 10^23 molecules/mol) = 1.51 x 10^22 oxygen molecules.