How Many Water Molecules Are in a Full 500 ml Water Bottle?

A typical water bottle holds 500 ml of water. To determine how many water molecules are in a full water bottle, we need to understand the relationship between volume, mass, and the number of molecules.

First, let’s start with the given information:

• 1 ml of water weighs 1 gram.
• Therefore, 500 ml of water weighs 500 grams.

Next, we need to know the molar mass of water. The molar mass of water (H₂O) is approximately 18 grams per mole. This means that 18 grams of water contain 1 mole of water molecules.

To find the number of moles in 500 grams of water, we use the formula:

Number of moles = Mass (in grams) / Molar mass (in grams per mole)

Plugging in the values:

Number of moles = 500 grams / 18 grams per mole ≈ 27.78 moles

Now, we need to find the number of water molecules. Avogadro’s number tells us that 1 mole of any substance contains approximately 6.022 × 10²³ molecules. Therefore, the number of water molecules in 27.78 moles is:

Number of molecules = Number of moles × Avogadro’s number

Number of molecules = 27.78 moles × 6.022 × 10²³ molecules/mole ≈ 1.673 × 10²⁵ molecules

So, a full 500 ml water bottle contains approximately 1.673 × 10²⁵ water molecules.