Use this calculator to determine the mass, molar mass, or number of moles of a substance. Enter any two values to calculate the third.
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function calculateMolar() {
var massInput = document.getElementById("massInput").value;
var molarMassInput = document.getElementById("molarMassInput").value;
var molesInput = document.getElementById("molesInput").value;
var resultDiv = document.getElementById("molarResult");
var mass = parseFloat(massInput);
var molarMass = parseFloat(molarMassInput);
var moles = parseFloat(molesInput);
var filledCount = 0;
if (!isNaN(mass)) filledCount++;
if (!isNaN(molarMass)) filledCount++;
if (!isNaN(moles)) filledCount++;
resultDiv.className = "calculator-result"; // Reset class
if (filledCount !== 2) {
resultDiv.innerHTML = "Please enter exactly two values to calculate the third.";
resultDiv.classList.add("error");
return;
}
if (isNaN(moles)) {
// Calculate Moles: Moles = Mass / Molar Mass
if (isNaN(mass) || isNaN(molarMass)) {
resultDiv.innerHTML = "Error: Missing required values for calculation.";
resultDiv.classList.add("error");
return;
}
if (molarMass === 0) {
resultDiv.innerHTML = "Error: Molar Mass cannot be zero.";
resultDiv.classList.add("error");
return;
}
var calculatedMoles = mass / molarMass;
resultDiv.innerHTML = "Calculated Moles: " + calculatedMoles.toFixed(4) + " mol";
} else if (isNaN(mass)) {
// Calculate Mass: Mass = Moles * Molar Mass
if (isNaN(moles) || isNaN(molarMass)) {
resultDiv.innerHTML = "Error: Missing required values for calculation.";
resultDiv.classList.add("error");
return;
}
var calculatedMass = moles * molarMass;
resultDiv.innerHTML = "Calculated Mass: " + calculatedMass.toFixed(4) + " g";
} else if (isNaN(molarMass)) {
// Calculate Molar Mass: Molar Mass = Mass / Moles
if (isNaN(mass) || isNaN(moles)) {
resultDiv.innerHTML = "Error: Missing required values for calculation.";
resultDiv.classList.add("error");
return;
}
if (moles === 0) {
resultDiv.innerHTML = "Error: Moles cannot be zero when calculating Molar Mass.";
resultDiv.classList.add("error");
return;
}
var calculatedMolarMass = mass / moles;
resultDiv.innerHTML = "Calculated Molar Mass: " + calculatedMolarMass.toFixed(4) + " g/mol";
} else {
resultDiv.innerHTML = "Error: Unexpected state. Please check inputs.";
resultDiv.classList.add("error");
}
}
Understanding Moles, Mass, and Molar Mass in Chemistry
In chemistry, the concepts of moles, mass, and molar mass are fundamental for understanding the quantities of substances involved in reactions and compositions. This calculator helps you easily navigate between these three crucial measurements.
What is a Mole?
The mole (mol) is the SI unit for the amount of substance. It's a way of counting atoms, molecules, ions, or other elementary entities. One mole of any substance contains approximately 6.022 x 1023 particles, a number known as Avogadro's number. Just as a "dozen" means 12 of something, a "mole" means 6.022 x 1023 of something. This large number is necessary because atoms and molecules are incredibly small.
What is Mass?
Mass, in this context, refers to the quantity of matter in a substance, typically measured in grams (g). When we talk about the mass of a substance in a chemical context, we are often referring to the total mass of all the atoms or molecules present.
What is Molar Mass?
Molar mass (M) is the mass of one mole of a substance, expressed in grams per mole (g/mol). For an element, the molar mass is numerically equal to its atomic mass found on the periodic table (e.g., the molar mass of Carbon is approximately 12.01 g/mol). For a compound, the molar mass is the sum of the atomic masses of all the atoms in its chemical formula. For example, the molar mass of water (H2O) is approximately (2 x 1.008 g/mol for H) + (1 x 15.999 g/mol for O) = 18.015 g/mol.
The Relationship: The Molar Formula
These three quantities are interconnected by a simple formula:
Moles (n) = Mass (m) / Molar Mass (M)
From this, we can derive two other useful forms:
Mass (m) = Moles (n) × Molar Mass (M)
Molar Mass (M) = Mass (m) / Moles (n)
How to Use the Molar Calculator
Our Molar Calculator simplifies these calculations. You only need to input any two of the three values (Mass, Molar Mass, or Moles), and the calculator will automatically determine the third. Here are some examples:
Example 1: Calculating Moles
You have 100 grams of water (H2O). You know the molar mass of water is approximately 18.015 g/mol.
Enter "100" into the "Mass (g)" field.
Enter "18.015" into the "Molar Mass (g/mol)" field.
Leave the "Moles (mol)" field empty.
Click "Calculate".
The calculator will show: Calculated Moles: 5.5509 mol
Example 2: Calculating Mass
You need 2 moles of sodium chloride (NaCl) for an experiment. The molar mass of NaCl is approximately 58.44 g/mol.
Leave the "Mass (g)" field empty.
Enter "58.44" into the "Molar Mass (g/mol)" field.
Enter "2" into the "Moles (mol)" field.
Click "Calculate".
The calculator will show: Calculated Mass: 116.8800 g
Example 3: Calculating Molar Mass
You have an unknown substance with a mass of 50 grams, and you've determined it contains 0.5 moles.
Enter "50" into the "Mass (g)" field.
Leave the "Molar Mass (g/mol)" field empty.
Enter "0.5" into the "Moles (mol)" field.
Click "Calculate".
The calculator will show: Calculated Molar Mass: 100.0000 g/mol
This calculator is an invaluable tool for students, educators, and professionals in chemistry, making stoichiometric calculations quicker and more accurate.