Tools in This Collection
Dilution Equation Calculator
Solve C1V1 = C2V2 for any dilution variable
pH to Concentration Calculator
Convert between pH and hydrogen ion concentration
Chemical Equation Balancer
Balance chemical equations with correct stoichiometric coefficients
Molecular Weight Calculator
Calculate molar mass from chemical formula
Molarity Calculator
Calculate molarity, moles, or volume for solutions
Percent Composition Calculator
Find mass percent of each element in a compound
Stoichiometry Calculator
Convert between reactants and products using mole ratios
Boiling Point Elevation
Calculate ΔTb = Kb × m × i for colligative properties
Freezing Point Depression
Calculate ΔTf = Kf × m × i for freezing point changes
Specific Gravity Calculator
Calculate specific gravity and solution density conversions
Chemistry Problem-Solving Workflow
Chemistry calculations follow a predictable path: convert measured masses or volumes to moles using molar mass, apply stoichiometric ratios from the balanced equation, then convert back to grams or liters. Getting this workflow right makes even complex multi-step problems manageable. Start with the Molecular Weight Calculator to find molar masses, then move to the Stoichiometry Calculator for reaction quantities.
Dilution: C₁V₁ = C₂V₂
The dilution equation C₁V₁ = C₂V₂ conserves moles of solute across a dilution. To prepare 600 mL of 1 M HCl from 6 M HCl: 6 × V₁ = 1 × 600, so V₁ = 100 mL. Take 100 mL of the concentrated acid and add water to make 600 mL total. Always add acid to water (not water to acid) for safety. The Dilution Equation Calculator solves for any of the four variables.
Molarity and Concentration
Molarity M = moles of solute / liters of solution. To prepare 500 mL of 2 M NaCl: moles needed = 2 × 0.5 = 1 mol. NaCl molar mass = 23 + 35.5 = 58.5 g/mol, so you need 1 × 58.5 = 58.5 g of NaCl dissolved in water to make 500 mL. The Molarity Calculator handles concentration, moles, and volume calculations. The pH to Concentration Calculator converts between pH and hydrogen ion concentration ([H⁺] = 10⁻ᵖᴴ at 25°C).
Stoichiometry and Limiting Reagents
Stoichiometry converts between reactants and products using mole ratios from the balanced equation. For 2H₂ + O₂ → 2H₂O: if you have 4 mol H₂ and 3 mol O₂, the 4 mol H₂ requires only 2 mol O₂ — so O₂ is in excess and H₂ is the limiting reagent, producing 4 mol H₂O. The Chemical Equation Balancer provides the balanced equation with correct coefficients, and the Stoichiometry Calculator handles the mole ratio conversions.
Colligative Properties
Boiling point elevation and freezing point depression depend on solute concentration (molality), not identity. ΔTb = Kb × m × i, where Kb is the molal boiling point elevation constant (0.512°C·kg/mol for water), m is molality (mol/kg), and i is the van't Hoff factor (1 for nonelectrolytes, 2 for NaCl, 3 for CaCl₂). Dissolving 1 mol of NaCl (i = 2) in 1 kg water raises the boiling point by 0.512 × 1 × 2 = 1.024°C. The Boiling Point Elevation and Freezing Point Depression calculators handle these directly. For solution density and concentration conversions, use the Specific Gravity Calculator. The Percent Composition Calculator finds the mass percent of each element in a compound.
Frequently Asked Questions
How do I calculate dilutions using C1V1 = C2V2?
The equation C₁V₁ = C₂V₂ states that moles of solute before and after dilution are equal. To find how much stock solution to use: V₁ = (C₂ × V₂) / C₁. For 200 mL of 0.5 M NaOH from 2 M stock: V₁ = (0.5 × 200) / 2 = 50 mL. Take 50 mL of stock and add water to reach 200 mL total. Always use consistent units (both volumes in mL or both in L).
What is the difference between molarity and molality?
Molarity (M) is moles of solute per liter of solution — it changes with temperature because volume changes. Molality (m) is moles of solute per kilogram of solvent — it's temperature-independent. For dilute aqueous solutions they're nearly equal, but for colligative property calculations (boiling point elevation, freezing point depression) you must use molality. The van't Hoff factor i accounts for electrolytes that dissociate: i = 1 for glucose, i = 2 for NaCl, i = 3 for CaCl₂.
How do I balance chemical equations?
Balancing ensures equal atoms of each element on both sides. Start with the most complex molecule, balance atoms one element at a time (save H and O for last), then use the smallest whole-number coefficients. For combustion of methane: CH₄ + O₂ → CO₂ + H₂O. Balance C first (1 on each side), then H (4 on left → 2H₂O on right), then O (2 in CO₂ + 1 in H₂O = 4, so 2O₂ on left). Balanced: CH₄ + 2O₂ → CO₂ + 2H₂O.
What is molarity and how do I prepare a solution?
Molarity M = moles of solute / liters of solution. To prepare a solution: (1) Calculate grams needed = M × V (in liters) × molar mass. (2) Weigh out that mass of solute. (3) Dissolve in a small amount of solvent. (4) Transfer to a volumetric flask and add solvent to the target volume. For 250 mL of 1 M NaCl (MW 58.44 g/mol): need 1 × 0.25 × 58.44 = 14.61 g of NaCl.