Balance chemical equations and calculate molar quantities for any reaction. Convert between moles, grams, molecules, and liters at STP with ease.
Enter a chemical equation below (e.g. H2 + O2 → H2O), click Balance, then select a known substance and enter its amount to calculate all other quantities.
Methane burns in oxygen to produce carbon dioxide and water. How much CO₂ is produced when 16 g of CH₄ is burned?
Molar masses: CH₄ = 16.04 g/mol, O₂ = 32.00 g/mol, CO₂ = 44.01 g/mol, H₂O = 18.02 g/mol
16 g CH₄ = 0.9975 mol → produces 0.9975 mol CO₂ = 43.90 g CO₂
Nitrogen and hydrogen combine to form ammonia. How many moles of NH₃ are produced from 3 moles of H₂?
The mole ratio is 3 mol H₂ : 2 mol NH₃, so 3 mol H₂ produces 2.0 mol NH₃
Calcium carbonate decomposes upon heating to form calcium oxide and carbon dioxide. How many grams of CaO are produced from 100 g of CaCO₃?
Molar masses: CaCO₃ = 100.09 g/mol, CaO = 56.08 g/mol, CO₂ = 44.01 g/mol
100 g CaCO₃ = 0.9991 mol → produces 56.03 g CaO and 43.97 g CO₂
Sodium hydroxide neutralizes hydrochloric acid to produce salt and water. How many grams of NaCl are produced from 0.5 moles of HCl?
Molar masses: HCl = 36.46 g/mol, NaOH = 40.00 g/mol, NaCl = 58.44 g/mol, H₂O = 18.02 g/mol
0.5 mol HCl produces 0.5 mol NaCl = 29.22 g NaCl
Water decomposes into hydrogen and oxygen gas. What volume of H₂ gas at STP is produced from 36 g of water?
Molar mass H₂O = 18.02 g/mol. 36 g H₂O = 1.998 mol
Produces 1.998 mol H₂ → at STP (22.414 L/mol) = 44.78 L H₂ gas
In a chemical reaction, matter is neither created nor destroyed. The total mass of reactants equals the total mass of products. This is the fundamental principle behind balancing chemical equations.
Stoichiometry is the calculation of reactants and products in chemical reactions. It uses the balanced chemical equation to determine the quantitative relationships between substances. The coefficients in a balanced equation represent the mole ratios of each substance involved.
Moles = Mass (g) ÷ Molar Mass (g/mol)
H2 + O2 → H2O)The calculator uses a brute-force balancing algorithm that searches for integer coefficients from 1 to 5. It supports all common elements with accurate molar masses from the IUPAC standard periodic table. For gas volumes, it uses the STP (Standard Temperature and Pressure) molar volume of 22.414 L/mol.
Stoichiometry is the branch of chemistry that deals with the quantitative relationships between reactants and products in chemical reactions. The word comes from the Greek words stoicheion (element) and metron (measure). It is fundamental to understanding how much of each substance is involved in a chemical reaction.
At its core, stoichiometry relies on the law of conservation of mass and the balanced chemical equation. The coefficients in a balanced equation tell you the mole ratio of each substance. For example, in the reaction 2H₂ + O₂ → 2H₂O, the ratio tells you that 2 moles of hydrogen react with 1 mole of oxygen to produce 2 moles of water.
Stoichiometry is essential for chemists, students, and professionals in many fields. It allows you to calculate the exact amounts of reactants needed for a reaction or the expected yield of products. Applications include drug formulation, industrial chemical production, environmental analysis, fuel combustion calculations, and laboratory experiments.
Our Stoichiometry Calculator is valuable for a wide range of scenarios:
STP stands for Standard Temperature and Pressure (0°C or 273.15 K, and 1 atm or 101.325 kPa). At STP, one mole of an ideal gas occupies exactly 22.414 liters. This is derived from the ideal gas law: V = nRT/P = (1 mol × 0.082057 L·atm/mol·K × 273.15 K) / 1 atm = 22.414 L.
The calculator uses a brute-force approach that tries integer coefficients from 1 to 5 for each substance. For each combination, it checks whether the number of atoms of each element is equal on both sides of the equation. If no solution is found with small coefficients, it expands the search range. This works reliably for most common chemical reactions.
Yes, the calculator treats polyatomic ions as groups of atoms. For example, in CaCO₃, it counts Ca, C, and O atoms separately. The balancing algorithm works at the atom level, so any compound formula with standard element symbols is supported.
The calculator supports four units: moles (the base unit), grams (mass = moles × molar mass), molecules (molecules = moles × 6.022×10²³), and liters at STP (volume = moles × 22.414 L/mol, for gases only). You can enter your known amount in any of these units and see results in all of them.
Yes, the calculator uses IUPAC standard atomic masses for all common elements. Molar masses are calculated by summing the atomic masses of all atoms in each compound formula, providing accurate values for stoichiometric calculations.
⚠️ Important Note: While this calculator provides accurate results for educational and general purposes, always verify critical calculations with additional sources. Real chemical reactions may involve side reactions, incomplete conversion, and non-ideal behavior. Use proper safety equipment when handling chemicals. This tool is for reference and learning — consult professional resources for laboratory-grade work.