Chemistry Calculators
Perform essential chemistry calculations with our free chemistry calculators. Calculate molar concentrations and molecular weights instantly with step-by-step solutions, periodic table integration, and practical examples for students, researchers, and laboratory professionals.
Molarity Calculator
Calculate the molarity of a solution from moles of solute and volume of solution.
Molecular Weight Calculator
Calculate the molecular weight of any chemical compound from its molecular formula.
How to Choose the Right Chemistry Calculator
Use the molarity calculator when preparing solutions in the laboratory. Enter the mass of solute, its molar mass, and the solution volume to find the molar concentration. It also handles dilution calculations using the M1V1 = M2V2 formula, which is essential when you need to prepare a less concentrated solution from a stock solution.
The molecular weight calculator is your first step when you need the molar mass of a compound. Simply enter the chemical formula (like H2O, NaCl, or C6H12O6) and the calculator breaks down the contribution of each element using accurate atomic masses from the periodic table. Use this result as input for the molarity calculator or any other calculation requiring molar mass.
Understanding Chemistry Calculations
Chemistry is the science of matter and the changes it undergoes. Quantitative chemistry relies heavily on the concept of the mole, a counting unit that bridges the gap between individual atoms and macroscopic quantities. One mole contains exactly 6.02214076 x 10^23 entities (Avogadro's number), whether those entities are atoms, molecules, ions, or electrons.
Molarity (M) is the most common way to express solution concentration in chemistry. It is defined as the number of moles of solute per liter of solution: M = moles / liters. A 1 M solution of NaCl contains 58.44 grams of NaCl (its molar mass) dissolved in enough water to make exactly 1 liter of solution. Molarity is essential for stoichiometric calculations, titrations, and reaction rate studies.
Molecular weight (molar mass) is the sum of the atomic masses of all atoms in a molecule, expressed in grams per mole (g/mol). Water (H2O) has a molecular weight of approximately 18.015 g/mol: two hydrogen atoms (2 x 1.008) plus one oxygen atom (15.999). Knowing the molecular weight is necessary for converting between grams and moles, a fundamental step in virtually every quantitative chemistry calculation.
The dilution equation M1V1 = M2V2 describes the relationship between the concentration and volume of a solution before and after dilution. Since dilution adds solvent without changing the amount of solute, the product of molarity and volume (which represents moles of solute) must remain constant. This principle is used daily in laboratories to prepare working solutions from concentrated stock solutions.
Frequently Asked Questions
How do I calculate molarity?
Molarity (M) = moles of solute / liters of solution. First find the moles of solute by dividing its mass (in grams) by its molar mass (in g/mol). Then divide by the volume of the solution in liters. For example, dissolving 58.44g of NaCl (molar mass 58.44 g/mol) in 1 liter gives a 1.0 M solution. Our molarity calculator handles the unit conversions and arithmetic automatically.
How do I use the dilution formula M1V1 = M2V2?
Identify the initial molarity (M1) and volume (V1) of your concentrated solution, and the desired final molarity (M2) or volume (V2). Solve for the unknown. For example, to make 500 mL of 0.1 M HCl from 1.0 M stock: (1.0)(V1) = (0.1)(500), so V1 = 50 mL. Measure 50 mL of stock solution and dilute it to a total volume of 500 mL with water.
How do I find the molecular weight of a compound?
Look up the atomic mass of each element on the periodic table, multiply by the number of atoms of that element in the formula, and add all contributions. For glucose (C6H12O6): carbon (6 x 12.011 = 72.066) + hydrogen (12 x 1.008 = 12.096) + oxygen (6 x 15.999 = 95.994) = 180.156 g/mol. Our calculator parses the formula and performs this calculation automatically.
What is the difference between molecular weight and formula weight?
Molecular weight applies to covalent compounds that exist as distinct molecules (like H2O or glucose). Formula weight is the broader term used for ionic compounds (like NaCl) that form crystal lattices rather than discrete molecules. The calculation is identical: sum the atomic masses of all atoms in the formula. In practice, the terms are often used interchangeably, and our calculator handles both types.
Why is the mole concept important in chemistry?
The mole connects the atomic world to the macroscopic world. Individual atoms and molecules are far too small to count or weigh individually, but one mole (6.022 x 10^23 particles) of any substance has a mass in grams equal to its atomic or molecular weight. This allows chemists to predict how much of each reactant is needed and how much product will form in any chemical reaction (stoichiometry).