Molar Ratio Calculator
Calculate molar ratios between reactants and products in balanced chemical equations. Enter a balanced equation and select two substances to find their ratio.
Enter a balanced chemical equation
Formula of the first substance
Amount in moles
Formula of the second substance
What is a molar ratio in chemistry?
A molar ratio is the ratio of moles of one substance to moles of another in a balanced chemical equation. For example, in the reaction 2H₂ + O₂ → 2H₂O, the molar ratio of H₂ to O₂ is 2:1, and H₂ to H₂O is 1:1.
How do I find the molar ratio from a balanced equation?
Look at the coefficients in front of each compound in the balanced equation. In 2H₂ + O₂ → 2H₂O, the coefficient of H₂ is 2, O₂ is 1, and H₂O is 2. So the molar ratio of H₂ to O₂ is 2:1, meaning you need 2 moles of H₂ for every 1 mole of O₂.
Can I use the molar ratio to convert between substances?
Yes! Once you have the molar ratio from the balanced equation, you can convert between any two substances by multiplying the known amount by the ratio. For example, if you have 5 moles of H₂ and need to find how much O₂ is required: 5 mol H₂ × (1 mol O₂ / 2 mol H₂) = 2.5 mol O₂.
What happens if my equation is not balanced?
You cannot accurately calculate molar ratios from an unbalanced equation. Always ensure your chemical equation is properly balanced before calculating molar ratios. Use coefficients only, not subscripts.
How is molar ratio different from mass ratio?
Molar ratio uses coefficients and moles from the balanced equation, while mass ratio involves converting to mass using molar masses. For example, 2H₂ + O₂ → 2H₂O has a molar ratio of H₂:O₂ = 2:1, but a mass ratio of 4g H₂ : 32g O₂ = 1:8.
Where are molar ratios used in real applications?
Molar ratios are essential in stoichiometry, limiting reactant calculations, determining theoretical yield, and industrial processes like manufacturing ammonia (Haber process) and sulfuric acid (Contact process).