Final answer:
A water molecule (H₂O) consists of two hydrogen atoms and one oxygen atom. In two water molecules, there are 4 hydrogen atoms and 2 oxygen atoms. The ratio of hydrogen to oxygen in water is always 2:1.
Step-by-step explanation:
The chemical formula of water is H₂O, indicating that each molecule consists of two hydrogen atoms and one oxygen atom.
Therefore, in two water molecules there would be a total of 4 hydrogen atoms (since 2 molecules × 2 hydrogen atoms/molecule = 4 hydrogen atoms) and 2 oxygen atoms (since 2 molecules × 1 oxygen atom/molecule = 2 oxygen atoms).
The ratio of hydrogen to oxygen atoms in water is always 2:1.
This ratio is important in understanding the empirical formula, which reflects the simplest whole-number ratio of atoms in a compound.
The concept of moles is also significant in chemistry. A mole is Avogadro's number, which is 6.022×10²³, of molecules. When we say one mole of water molecules, it means 6.022×10²³ water molecules, and consequently, there would be twice as many hydrogen atoms, or 2 moles of hydrogen atoms, and one mole of oxygen atoms within that quantity of water.