Massa molecular (C_x H_y)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The molecular mass calculator for organic compounds (C_x H_y) computes the molar mass of molecules composed solely of carbon and hydrogen. The formula used is (12 × x) + y, where 'x' represents the number of carbon atoms and 'y' the number of hydrogen atoms. This tool is ideal for students and professionals needing to quickly determine the molecular mass of simple hydrocarbons like alkanes, alkenes, or alkynes.
To use the calculator, enter the values of x and y corresponding to the molecular formula of the compound. The calculation assumes a carbon atomic mass of 12 u and hydrogen of 1 u. For example, for ethane (C₂H₆), the molecular mass would be (12 × 2) + 6 = 30 u. Results are displayed instantly, enabling quick checks for exercises or lab analyses.
This calculator is useful in contexts such as stoichiometric calculations, density determination, or chemical reaction analysis. However, it does not account for other elements or complex structures like aromatic rings or functional groups. For organic compounds containing oxygen, nitrogen, or halogens, more comprehensive tools are required.
When using the calculator, avoid confusing molecular mass with molar mass in g/mol. Additionally, ensure the provided formula exactly matches the analyzed compound, especially in cases of isomerism. Calculation accuracy depends on correctly identifying the number of carbon and hydrogen atoms in the molecular structure.
Frequently asked questions
Why does the formula consider only carbon and hydrogen?
The calculator is designed for organic compounds composed solely of carbon and hydrogen, such as hydrocarbons. Other elements require different calculations.
How can I use this tool for isomeric compounds?
The tool calculates molecular mass based on the molecular formula, not the structure. Isomers with the same formula (e.g., butane and isobutane) will have the same molecular mass.
Can this calculator be used for inorganic compounds?
No, as the formula is based on carbon and hydrogen. For inorganic compounds like H₂O or CO₂, use a calculator that includes other atomic masses.
Why doesn't the calculated molecular mass match experimental results?
Check if the molecular formula is correct and if atom counts are accurate. Impurities or experimental errors can also affect results.
Does the calculator handle fractional values in molecular formulas?
No, because x and y must be integers representing atoms. Fractions indicate the need to balance the formula.