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Molarity Formula:
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Molarity (M) is a measure of the concentration of a solute in a solution, defined as the number of moles of solute per liter of solution. It's one of the most commonly used units of concentration in chemistry.
The calculator uses the molarity formula:
Where:
Explanation: The formula converts mass to moles (by dividing by molecular weight) and then divides by volume to get concentration in moles per liter.
Details: Accurate molarity calculations are essential for preparing solutions of known concentration, which is crucial for chemical reactions, biological assays, and medical applications.
Tips: Enter mass in grams, molecular weight in g/mol, and volume in liters. All values must be positive numbers. Molecular weight is typically found on chemical reagent bottles or in chemical databases.
Q1: What's the difference between molarity and molality?
A: Molarity is moles per liter of solution, while molality is moles per kilogram of solvent. Molarity changes with temperature (due to volume changes), while molality does not.
Q2: How do I find the molecular weight of a compound?
A: Sum the atomic weights of all atoms in the molecule. For example, water (H₂O) has MW = (2×1.008) + 15.999 = 18.015 g/mol.
Q3: Can I use milliliters for volume?
A: Yes, but you must convert to liters (divide by 1000) before using in the formula, as molarity is defined per liter.
Q4: What if my solute is a liquid?
A: For liquids, you can calculate mass from density (mass = volume × density) or use molarity directly if you know the concentration of the stock solution.
Q5: How precise should my measurements be?
A: Precision depends on your application. For most laboratory work, 4 significant figures is sufficient. Analytical chemistry may require higher precision.