Chemistry Calculators
Free molarity, molecular weight, and pH calculators. Quantitative chemistry tools using IUPAC standard values and formulas.
Chemistry Calculators - Quantitative Chemistry Made Precise
Quantitative chemistry requires exact numerical results: the precise concentration of a solution, the molecular weight of a compound, the pH of an acid or base. These calculators use IUPAC 2021 standard atomic masses and established formulas to give reliable answers every time.
Three Chemistry Calculators
Molarity Calculator - Molarity M = moles / litres = (mass in g ÷ molar mass) ÷ volume in litres. Three modes: find molarity from mass and volume, find mass for a target molarity and volume, or find volume for a given mass and target molarity. Also handles dilution using M₁V₁ = M₂V₂. The molar mass needed for input comes from the Molecular Weight Calculator.
Molecular Weight Calculator - Parses chemical formulas including parentheses and subscripts - Ca(OH)₂, Al₂(SO₄)₃, C₁₂H₂₂O₁₁ - using IUPAC 2021 standard atomic masses for all 118 elements. Returns molecular weight in g/mol and elemental composition percentages. The essential input for any molarity calculation.
pH Calculator - pH = −log₁₀[H⁺]. Modes: find pH from [H⁺], find [H⁺] from pH (reverse: [H⁺] = 10^(−pH)), find pOH (pOH = 14 − pH at 25°C), and classify acid/base/neutral. Also accepts [OH⁻] as input using Kw = 1.0 × 10⁻¹⁴ at 25°C. The logarithm used here is the same as in the Logarithm Calculator.
How These Three Calculators Connect
Example: preparing a buffer solution - (1) Use the Molecular Weight Calculator to find the molar mass of your solute. (2) Feed that into the Molarity Calculator to find how many grams to weigh out for your target concentration. (3) After mixing, use the pH Calculator to verify the [H⁺] matches your target pH.
Frequently Asked Questions
How do I prepare a 1 M solution of NaCl?
Molar mass of NaCl = 58.44 g/mol (from the Molecular Weight Calculator). For 1 L of 1 M solution, dissolve 58.44 g of NaCl in water and make up to 1,000 ml. Verify using the Molarity Calculator.
What atomic masses does the molecular weight calculator use?
The Molecular Weight Calculator uses IUPAC 2021 standard atomic weights: H = 1.008, C = 12.011, N = 14.007, O = 15.999, Na = 22.990, S = 32.06, Cl = 35.45, Ca = 40.078, Fe = 55.845.
What is the relationship between pH and pOH?
pH + pOH = 14 at 25°C, derived from Kw = [H⁺][OH⁻] = 1.0 × 10⁻¹⁴. So pH 3 means pOH = 11. The pH Calculator shows both values simultaneously.
Can the molarity calculator handle dilution calculations?
Yes. Switch to the dilution mode in the Molarity Calculator and enter any three of M₁, V₁, M₂, V₂ to find the fourth. Example: 5 ml of a 5 M stock solution diluted to 250 ml gives a 0.1 M working solution.