Molar Mass Calculator
Enter a formula and click 'Calculate' to see the molar mass.
Calculation Details:
- ";
var elementsInFormula = {}; // To store aggregated counts of elements
// Regex to match element symbols and their subscripts.
// It handles single uppercase letters (e.g., O, C) and
// uppercase followed by lowercase (e.g., Na, Cl).
// It also captures the subscript number, which can be empty (defaulting to 1).
// This parser does NOT handle parentheses (e.g., (NH4)2SO4).
var regex = /([A-Z][a-z]*)(\d*)/g;
var match;
var lastIndex = 0;
// First pass: parse elements and their counts
while ((match = regex.exec(formulaInput)) !== null) {
// Check for unparsed characters between matches, which might indicate invalid syntax
if (match.index > lastIndex) {
var invalidPart = formulaInput.substring(lastIndex, match.index);
if (invalidPart.trim() !== ") { // Allow spaces
resultDiv.innerHTML = "Invalid character(s) or syntax in formula: '" + invalidPart + "'. Please ensure correct element symbols and subscripts. This calculator does not support parentheses.";
return;
}
}
lastIndex = regex.lastIndex;
var elementSymbol = match[1];
var count = parseInt(match[2] || "1", 10); // Default to 1 if no subscript
if (isNaN(count) || count < 1) {
resultDiv.innerHTML = "Invalid subscript for element '" + elementSymbol + "'. Subscripts must be positive integers.";
return;
}
if (!atomicMasses[elementSymbol]) {
resultDiv.innerHTML = "Unknown element symbol: '" + elementSymbol + "'. Please check your formula.";
return;
}
elementsInFormula[elementSymbol] = (elementsInFormula[elementSymbol] || 0) + count;
}
// Check if there are any remaining unparsed characters at the end
if (lastIndex 0) {
resultDiv.innerHTML = "Could not parse the chemical formula. Please ensure it is correctly formatted (e.g., H2O, C6H12O6) and does not contain parentheses.";
return;
}
// Second pass: calculate total molar mass and build details
for (var symbol in elementsInFormula) {
if (elementsInFormula.hasOwnProperty(symbol)) {
var count = elementsInFormula[symbol];
var mass = atomicMasses[symbol];
var elementTotal = count * mass;
totalMolarMass += elementTotal;
detailsHtml += "
- " + symbol + ": " + count + " × " + mass.toFixed(3) + " g/mol = " + elementTotal.toFixed(3) + " g/mol "; } } detailsHtml += "
Understanding Molar Mass
Molar mass is a fundamental concept in chemistry, representing the mass of one mole of a chemical substance. A mole is a unit of measurement that contains exactly 6.022 × 1023 elementary entities (like atoms, molecules, or ions), a number known as Avogadro's number. The molar mass is typically expressed in grams per mole (g/mol).
Knowing the molar mass of a compound is crucial for various chemical calculations, especially in stoichiometry, where it allows chemists to convert between the mass of a substance and the number of moles, and vice versa. This conversion is essential for predicting reaction yields, determining reactant quantities, and understanding chemical processes.
How to Calculate Molar Mass Manually
To calculate the molar mass of a compound, you need to follow these steps:
- Identify all elements: Break down the chemical formula into its constituent elements.
- Determine the count of each element: Note the subscript next to each element symbol. If there's no subscript, it means there's one atom of that element.
- Find the atomic mass: Look up the atomic mass of each element from the periodic table. These are usually given in atomic mass units (amu), but for molar mass, we use the same numerical value in grams per mole (g/mol).
- Multiply and sum: For each element, multiply its atomic mass by its count in the formula. Then, sum up these products for all elements in the compound.
Manual Calculation Examples:
Example 1: Water (H2O)
- Hydrogen (H): 2 atoms × 1.008 g/mol = 2.016 g/mol
- Oxygen (O): 1 atom × 15.999 g/mol = 15.999 g/mol
- Total Molar Mass = 2.016 + 15.999 = 18.015 g/mol
Example 2: Glucose (C6H12O6)
- Carbon (C): 6 atoms × 12.011 g/mol = 72.066 g/mol
- Hydrogen (H): 12 atoms × 1.008 g/mol = 12.096 g/mol
- Oxygen (O): 6 atoms × 15.999 g/mol = 95.994 g/mol
- Total Molar Mass = 72.066 + 12.096 + 95.994 = 180.156 g/mol
Using the Molar Mass Calculator
Our Molar Mass Calculator simplifies this process. Just enter the chemical formula into the designated field, and the calculator will instantly provide the total molar mass along with a detailed breakdown of each element's contribution.
Important Notes for Formula Input:
- Use standard element symbols (e.g., 'H' for Hydrogen, 'Na' for Sodium, 'Cl' for Chlorine). Element symbols are case-sensitive (e.g., 'Co' for Cobalt, not 'CO' for Carbon Monoxide).
- Enter subscripts as numbers immediately following the element symbol (e.g., 'H2O' for water, 'C6H12O6' for glucose). If an element has no subscript, it implies a count of 1 (e.g., 'NaCl').
- This calculator currently supports simple chemical formulas without parentheses. For example, it can calculate 'H2SO4' but not complex formulas like '(NH4)2SO4'.
This tool is designed to be a quick and accurate resource for students, educators, and professionals in chemistry, helping to streamline calculations and enhance understanding of chemical composition.