1. What is Molarity of Pure Water?

Molarity represents the concentration of a solution, defined as the number of moles of solute per liter of solution. For pure water with density 1 g/mL, we can calculate its molarity using the formula.

2. How Does the Calculator Work?

The calculator uses the molarity formula:

Where:

• \( M \) — Molarity (mol/L)
• \( d \) — Density (g/mL)
• \( 1000 \) — Conversion factor (mL to L)
• \( MW \) — Molecular weight of water (18.015 g/mol)

Explanation: The formula converts density to molarity by accounting for the molecular weight of water and unit conversions.

3. Importance of Molarity Calculation

Details: Understanding the molarity of pure water is fundamental in chemistry for preparing solutions, understanding concentration relationships, and various analytical applications.

4. Using the Calculator

Tips: Enter the density of water in g/mL. For pure water at standard conditions, the density is approximately 1 g/mL at 4°C.

5. Frequently Asked Questions (FAQ)

Q1: Why is the molarity of pure water approximately 55.51 mol/L?
A: This value comes from the calculation (1 g/mL × 1000 mL/L) ÷ 18.015 g/mol = 55.51 mol/L, representing the concentration of water molecules in pure water.

Q2: Does temperature affect the molarity of water?
A: Yes, density changes with temperature, which affects molarity. The calculation assumes standard conditions (typically 4°C where density is exactly 1 g/mL).

Q3: Why use 18.015 g/mol for water's molecular weight?
A: This accounts for the natural abundance of hydrogen and oxygen isotopes, giving the average molecular weight of natural water.

Q4: Can this calculation be used for other pure substances?
A: Yes, the same principle applies: M = (density × 1000) / molecular weight, but only for pure substances.

Q5: How accurate is this calculation for real-world applications?
A: For most practical purposes, this provides sufficient accuracy, though extremely precise applications may require temperature corrections.