Calculadora de Razão Molar
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
r = n_A / n_B
About this calculator
The Molar Ratio Calculator determines the proportion between the amounts of substances (in moles) of two components in a mixture or chemical reaction. The molar ratio is calculated by dividing the number of moles of component A by the number of moles of component B: r = n_A / n_B. This tool is essential for stoichiometry, allowing you to check if reactants are in the correct proportion or to calculate theoretical yields.
To use the calculator, enter the mole values of each component. The result is a dimensionless number indicating how many times the amount of A is greater or smaller than B. For example, if n_A = 2 mol and n_B = 1 mol, the ratio is 2.0, meaning there is twice as much A as B. This information is crucial in chemical syntheses, solution preparation, and mixture analysis.
The molar ratio is widely used in laboratories and industries to ensure reactions occur efficiently. In processes like acid-base neutralization or combustion, the correct proportion avoids excess reactants and waste. The calculator also helps convert between mass and moles, provided the molar masses are known, facilitating experimental planning.
Cautions: ensure the units are in moles (not mass or volume). If you have masses, convert them to moles using the molar mass before using the calculator. Also, the order of components matters: the ratio A/B is different from B/A. Verify that you are entering the correct values for your desired context.
Frequently asked questions
What does a molar ratio greater than 1 mean?
It indicates that the amount of component A is greater than component B. For example, a ratio of 3 means there are 3 moles of A for every mole of B.
Can I use masses instead of moles in the calculator?
Not directly. The calculator expects values in moles. Convert mass to moles using the formula: moles = mass (g) / molar mass (g/mol).
Does the order of components affect the result?
Yes. The molar ratio A/B is the inverse of B/A. For example, if A/B = 2, then B/A = 0.5. Choose the order according to your need.
How is molar ratio used in stoichiometry?
It helps determine the ideal proportion between reactants and products. For example, in the reaction 2H₂ + O₂ → 2H₂O, the H₂/O₂ molar ratio should be 2 for complete consumption.
Does the calculator work for mixtures with more than two components?
No, it calculates the ratio between only two components. For multiple components, calculate pairs separately.