Home
Back
Molarity Formula:
| From: | To: |
The molarity of pure water represents the number of moles of water per liter of solution. For pure water with a density of 1 g/mL, this calculation provides the fundamental concentration value used in many chemical calculations.
The calculation uses the formula:
Where:
Explanation: This calculation converts the density of water to grams per liter, then divides by the molecular weight to find moles per liter.
Details: Knowing the molarity of pure water is essential for preparing solutions, understanding aqueous chemistry, and serves as a reference point in many laboratory procedures and chemical calculations.
Tips: This calculator automatically uses the standard values for pure water density (1 g/mL) and molecular weight of water (18 g/mol). Simply click "Calculate" to see the result.
Q1: Why is the molarity of water approximately 55.56 M?
A: This value comes from dividing the density of water (1000 g/L) by its molecular weight (18 g/mol), resulting in approximately 55.56 moles per liter.
Q2: Does temperature affect this calculation?
A: Yes, water density changes slightly with temperature, but the standard calculation uses the density at 4°C where water is most dense (1.000 g/mL).
Q3: Why is this calculation important in chemistry?
A: It provides the reference concentration for water in aqueous solutions and is fundamental to understanding concentration relationships in many chemical reactions.
Q4: Can this value be used for practical laboratory work?
A: Yes, this value is used when preparing solutions where water is both solvent and reactant, and for calculating the concentration of water in various chemical processes.
Q5: How does this relate to the concept of pH in pure water?
A: The molarity of water is directly related to the autoionization constant of water (K_w = [H⁺][OH⁻] = 10⁻¹⁴), which determines the pH of pure water (pH = 7 at 25°C).