To determine the mass of water containing 19 atoms of oxygen, we need to calculate the molar mass of water and then use the ratio between the number of oxygen atoms and the total number of atoms in water.
The chemical formula for water is H₂O, indicating that each water molecule contains two hydrogen atoms (H) and one oxygen atom (O).
The molar mass of water (H₂O) is calculated as follows:
- The molar mass of hydrogen (H) is approximately 1.008 g/mol.
- The molar mass of oxygen (O) is approximately 15.999 g/mol.
- Since water has two hydrogen atoms and one oxygen atom, the molar mass of water is: (2 × molar mass of hydrogen) + molar mass of oxygen = (2 × 1.008 g/mol) + 15.999 g/mol = 18.015 g/mol.
Now, we know that one mole of water (H₂O) contains one mole of oxygen atoms (O). This means that the ratio of oxygen atoms to water molecules is 1:1.
To find the mass of water containing 19 atoms of oxygen, we can set up the following proportion:
19 atoms of oxygen / (1 mole of oxygen / Avogadro's number) = X grams of water / (18.015 g/mol)
Avogadro's number is approximately 6.022 × 10^23 atoms/mol.
Simplifying the proportion, we get:
19 / (6.022 × 10^23) = X / 18.015
Solving for X (the mass of water containing 19 atoms of oxygen), we get:
X = (19 / (6.022 × 10^23)) × 18.015
Calculating this expression:
X ≈ 5.697 × 10^-22 grams
Therefore, the mass of water containing 19 atoms of oxygen is approximately 5.697 × 10^-22 grams.