Enter the chemical formula (e.g., H2O, NaCl, C6H12O6).
Molar Mass will be displayed here.
Understanding Molar Mass
Molar mass is a fundamental property of a chemical substance. It is defined as the mass of one mole of that substance. A mole is a unit of measurement used in chemistry to represent a specific quantity of particles (atoms, molecules, ions, etc.). It's equivalent to Avogadro's number, which is approximately 6.022 x 10^23 particles.
The molar mass is typically expressed in grams per mole (g/mol). It's numerically equal to the atomic weight (for elements) or molecular weight (for compounds) when expressed in atomic mass units (amu), but the units are different.
How to Calculate Molar Mass
To calculate the molar mass of a compound, you need to:
Identify all the elements present in the chemical formula.
Determine the number of atoms of each element in one molecule (indicated by subscripts in the formula).
Find the atomic mass of each element from the periodic table.
Multiply the atomic mass of each element by the number of atoms of that element in the formula.
Sum up the results from step 4 for all elements to get the total molar mass of the compound.
For example, to calculate the molar mass of water (H2O):
Hydrogen (H): Atomic mass ≈ 1.008 g/mol. There are 2 hydrogen atoms. So, 2 * 1.008 g/mol = 2.016 g/mol.
Oxygen (O): Atomic mass ≈ 15.999 g/mol. There is 1 oxygen atom. So, 1 * 15.999 g/mol = 15.999 g/mol.
Total Molar Mass of H2O = 2.016 g/mol + 15.999 g/mol = 18.015 g/mol.
Why is Molar Mass Important?
Molar mass is crucial for:
Stoichiometry: Relating the amounts of reactants and products in chemical reactions.
Solution Preparation: Calculating the amount of solute needed to create solutions of specific concentrations.
Interconversion: Converting between mass, moles, and the number of particles.
Chemical Analysis: Identifying unknown substances based on their molar mass.
This calculator simplifies the process by looking up common atomic masses and performing the calculations for you. Please ensure you enter the chemical formula accurately.
// Atomic masses for common elements (approximate values)
// This is a simplified list. For high precision, a more comprehensive dataset is needed.
var atomicMasses = {
"H": 1.008, "He": 4.003, "Li": 6.941, "Be": 9.012, "B": 10.811, "C": 12.011, "N": 14.007, "O": 15.999, "F": 18.998, "Ne": 20.180,
"Na": 22.990, "Mg": 24.305, "Al": 26.982, "Si": 28.086, "P": 30.974, "S": 32.065, "Cl": 35.453, "Ar": 39.948, "K": 39.098, "Ca": 40.078,
"Sc": 44.956, "Ti": 47.867, "V": 50.942, "Cr": 51.996, "Mn": 54.938, "Fe": 55.845, "Co": 58.933, "Ni": 58.693, "Cu": 63.546, "Zn": 65.38,
"Ga": 69.723, "Ge": 72.630, "As": 74.922, "Se": 78.971, "Br": 79.904, "Kr": 83.798, "Rb": 85.468, "Sr": 87.62, "Y": 88.906, "Zr": 91.224,
"Nb": 92.906, "Mo": 95.95, "Tc": 98.0, "Ru": 101.07, "Rh": 102.906, "Pd": 106.42, "Ag": 107.868, "Cd": 112.414, "In": 114.818, "Sn": 118.710,
"Sb": 121.760, "Te": 127.60, "I": 126.904, "Xe": 131.293, "Cs": 132.905, "Ba": 137.327, "La": 138.905, "Ce": 140.116, "Pr": 140.908, "Nd": 144.242,
"Pm": 145.0, "Sm": 150.36, "Eu": 151.964, "Gd": 157.25, "Tb": 158.925, "Dy": 162.500, "Ho": 164.930, "Er": 167.259, "Tm": 168.934, "Yb": 173.054,
"Lu": 174.966, "Hf": 178.49, "Ta": 180.948, "W": 183.84, "Re": 186.207, "Os": 190.23, "Ir": 192.217, "Pt": 195.084, "Au": 196.967, "Hg": 200.59,
"Tl": 204.383, "Pb": 207.2, "Bi": 208.980, "Po": 209.0, "At": 210.0, "Rn": 222.0, "Fr": 223.0, "Ra": 226.0, "Ac": 227.0, "Th": 232.038,
"Pa": 231.036, "U": 238.029, "Np": 237.0, "Pu": 244.0, "Am": 243.0, "Cm": 247.0, "Bk": 247.0, "Cf": 251.0, "Es": 252.0, "Fm": 257.0,
"Md": 258.0, "No": 259.0, "Lr": 266.0, "Rf": 267.0, "Db": 268.0, "Sg": 269.0, "Bh": 270.0, "Hs": 269.0, "Mt": 278.0, "Ds": 281.0,
"Rg": 282.0, "Cn": 285.0, "Nh": 286.0, "Fl": 289.0, "Mc": 290.0, "Lv": 293.0, "Ts": 294.0, "Og": 294.0
};
function calculateMolarMass() {
var formula = document.getElementById("chemicalFormula").value.trim();
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = 'Molar Mass will be displayed here.'; // Reset result
if (!formula) {
resultDiv.innerHTML = 'Please enter a chemical formula.';
resultDiv.style.backgroundColor = '#ffc107'; // Warning yellow
return;
}
var totalMolarMass = 0;
var formulaErrors = [];
// Regex to parse the formula: captures element symbol (capital letter followed by optional lowercase) and its count.
// It handles cases like H2O, CO2, C6H12O6, SO4(2-), etc.
// This regex is a bit simplified and might need adjustment for complex ions or hydrates.
var elementRegex = /([A-Z][a-z]*)(\d*)/g;
var match;
while ((match = elementRegex.exec(formula)) !== null) {
var elementSymbol = match[1];
var countStr = match[2];
var count = countStr === " ? 1 : parseInt(countStr, 10);
if (isNaN(count)) {
formulaErrors.push("Invalid count for element '" + elementSymbol + "'");
continue;
}
if (atomicMasses[elementSymbol]) {
totalMolarMass += atomicMasses[elementSymbol] * count;
} else {
formulaErrors.push("Atomic mass not found for element '" + elementSymbol + "'. Please check the symbol or ensure it's in the lookup table.");
}
}
if (formulaErrors.length > 0) {
resultDiv.innerHTML = 'Error: ' + formulaErrors.join(', ');
resultDiv.style.backgroundColor = '#dc3545'; // Error red
} else if (totalMolarMass > 0) {
resultDiv.innerHTML = totalMolarMass.toFixed(3) + ' g/mol' +
'Molar Mass of ' + formula + '';
resultDiv.style.backgroundColor = 'var(–success-green)'; // Success green
} else if (formula.length > 0) {
// This case might happen if the formula was entered but parsing failed entirely
resultDiv.innerHTML = 'Could not parse the formula. Please check format.';
resultDiv.style.backgroundColor = '#ffc107'; // Warning yellow
}
}