1. Pure Water:
* Highest concentration: Pure water has the highest concentration of water molecules, as it contains only water.
* Molarity: The molarity of pure water is approximately 55.5 M (moles per liter).
2. Solutions:
* Lower concentration: When a solute (like salt, sugar, or a chemical) is dissolved in water, the concentration of water molecules decreases.
* Dilution: The more solute added, the more diluted the water becomes.
* Concentration depends on solute: The specific concentration of water will vary depending on the amount and type of solute present.
* Example: A saltwater solution (NaCl dissolved in water) will have a lower concentration of water molecules than pure water.
Measuring Water Concentration:
While it's not typical to directly measure the concentration of water in solutions, we can infer its concentration by:
* Molarity of solute: Knowing the molarity of the solute allows us to calculate the molarity of water, considering the total volume of the solution.
* Measuring other properties: Some properties of solutions, like vapor pressure, freezing point, or osmotic pressure, are influenced by the concentration of water, allowing us to infer its concentration.
Key Point: The concentration of water in a solution is inversely proportional to the concentration of the solute. The more solute present, the lower the concentration of water molecules.
