Molarity Calculator
Calculate molarity, normality, and solution concentrations for chemistry lab work
Calculate Molarity & Concentration
How to Use
Calculate Molarity (M)
Molarity is the concentration of a solution expressed as moles of solute per liter of solution.
Formula
M = n / V
- M: Molarity (mol/L)
- n: Number of moles (mol)
- V: Volume of solution (L)
When to Use
Use this when you know the amount of substance (in moles) and the volume of solution.
Important Notes
- Always use consistent units (L for volume, g for mass)
- Temperature can affect solution volume
- Molarity changes with dilution
Try Sample Calculation
Click “Load Sample” to see a typical calculation for the selected type.
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How to Use the Molarity Calculator
Getting Started
- Step 1: Select the calculation type (molarity, moles, volume, or from mass)
- Step 2: Enter the known values in the appropriate fields
- Step 3: Click Calculate to get your result with detailed steps
- Step 4: Use Load Sample to see example calculations
Key Chemistry Concepts
- Molarity (M): Moles of solute per liter of solution (mol/L)
- Normality (N): Equivalent weight per liter for acid-base reactions
- Molality (m): Moles of solute per kilogram of solvent
- Molar Mass: Mass of one mole of substance (g/mol)
Laboratory Best Practices
- Accurate Measurements: Use volumetric flasks for precise volumes
- Temperature Control: Solutions expand/contract with temperature
- Proper Dissolution: Ensure complete solute dissolution
- Safety First: Always add acid to water, never water to acid
Common Applications
- Buffer Preparation: Creating pH-stable solutions
- Titration Analysis: Determining unknown concentrations
- Dilution Calculations: Preparing working solutions from stock
- Reaction Stoichiometry: Calculating reactant amounts
Frequently Asked Questions
What's the difference between molarity and molality?
Molarity (M) uses liters of solution in the denominator, while molality (m) uses kilograms of solvent. Molarity changes with temperature, but molality doesn't.
How do I calculate normality from molarity?
Normality = Molarity × number of equivalents. For HCl, N = M × 1. For H2SO4, N = M × 2. For bases, use the number of OH- ions.
Why does temperature affect molarity calculations?
Volume changes with temperature, so molarity (moles/volume) also changes. For precise work, specify temperature (usually 20°C or 25°C).
How do I prepare a solution from solid solute?
1) Calculate mass needed using M = (mass/MW)/V. 2) Dissolve in less water than final volume. 3) Transfer to volumetric flask. 4) Dilute to mark.
What's the difference between solution and solvent volume?
Solution volume is the total final volume. Solvent volume is less because adding solute increases total volume. Always use solution volume for molarity.
How accurate should my measurements be?
For most lab work, 0.1% accuracy is sufficient. Use analytical balances for mass (±0.0001g) and volumetric glassware for volume (±0.05mL).
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