Chemical Weight Calculation

:root {
–primary-color: #004a99;
–success-color: #28a745;
–background-color: #f8f9fa;
–text-color: #333;
–border-color: #ddd;
–card-bg: #fff;
–shadow-color: rgba(0, 0, 0, 0.1);
}
body {
font-family: ‘Segoe UI’, Tahoma, Geneva, Verdana, sans-serif;
background-color: var(–background-color);
color: var(–text-color);
line-height: 1.6;
margin: 0;
padding: 0;
}
.container {
max-width: 1000px;
margin: 20px auto;
padding: 20px;
background-color: var(–card-bg);
border-radius: 8px;
box-shadow: 0 4px 15px var(–shadow-color);
}
header {
background-color: var(–primary-color);
color: white;
padding: 20px 0;
text-align: center;
margin-bottom: 20px;
border-radius: 8px 8px 0 0;
}
header h1 {
margin: 0;
font-size: 2.5em;
}
h2, h3 {
color: var(–primary-color);
margin-top: 1.5em;
margin-bottom: 0.5em;
}
.calculator-section {
margin-bottom: 30px;
padding: 25px;
border: 1px solid var(–border-color);
border-radius: 6px;
background-color: var(–card-bg);
}
.calculator-section h2 {
text-align: center;
margin-top: 0;
margin-bottom: 25px;
font-size: 1.8em;
}
.input-group {
margin-bottom: 18px;
text-align: left;
}
.input-group label {
display: block;
margin-bottom: 8px;
font-weight: 500;
color: var(–primary-color);
}
.input-group input[type=”text”],
.input-group input[type=”number”],
.input-group select {
width: calc(100% – 22px);
padding: 10px 12px;
border: 1px solid var(–border-color);
border-radius: 4px;
font-size: 1em;
box-sizing: border-box;
}
.input-group input:focus,
.input-group select:focus {
outline: none;
border-color: var(–primary-color);
box-shadow: 0 0 0 3px rgba(0, 74, 153, 0.2);
}
.input-group .helper-text {
font-size: 0.85em;
color: #666;
margin-top: 5px;
display: block;
}
.error-message {
color: #dc3545;
font-size: 0.85em;
margin-top: 5px;
min-height: 1.2em; /* Prevent layout shift */
}
.button-group {
display: flex;
justify-content: space-between;
margin-top: 25px;
flex-wrap: wrap; /* Allow wrapping on smaller screens */
gap: 10px; /* Spacing between buttons */
}
.button-group button, .button-group input[type=”button”] {
padding: 12px 20px;
border: none;
border-radius: 5px;
cursor: pointer;
font-size: 1em;
font-weight: 500;
transition: background-color 0.3s ease, transform 0.2s ease;
flex: 1; /* Distribute space evenly */
min-width: 150px; /* Minimum width for buttons */
}
.button-group button.calculate-btn, .button-group input[type=”button”].calculate-btn {
background-color: var(–primary-color);
color: white;
}
.button-group button.calculate-btn:hover, .button-group input[type=”button”].calculate-btn:hover {
background-color: #003b7d;
transform: translateY(-2px);
}
.button-group button.reset-btn, .button-group input[type=”button”].reset-btn {
background-color: #6c757d;
color: white;
}
.button-group button.reset-btn:hover, .button-group input[type=”button”].reset-btn:hover {
background-color: #5a6268;
transform: translateY(-2px);
}
.button-group button.copy-btn, .button-group input[type=”button”].copy-btn {
background-color: var(–success-color);
color: white;
}
.button-group button.copy-btn:hover, .button-group input[type=”button”].copy-btn:hover {
background-color: #218838;
transform: translateY(-2px);
}
.results-container {
margin-top: 30px;
padding: 25px;
border: 1px solid var(–border-color);
border-radius: 6px;
background-color: #eef5fa; /* Slightly different background for results */
text-align: center;
}
.results-container h3 {
margin-top: 0;
font-size: 1.6em;
color: var(–primary-color);
border-bottom: 2px solid var(–primary-color);
padding-bottom: 10px;
display: inline-block;
}
.primary-result {
font-size: 2.5em;
font-weight: bold;
color: var(–success-color);
margin: 15px 0;
background-color: #fff;
padding: 15px;
border-radius: 6px;
box-shadow: 0 2px 8px var(–shadow-color);
}
.intermediate-results {
display: flex;
justify-content: space-around;
flex-wrap: wrap;
margin-top: 20px;
gap: 15px;
text-align: center;
}
.intermediate-results div {
padding: 15px;
border: 1px solid #ddd;
border-radius: 5px;
background-color: #fff;
box-shadow: 0 1px 5px var(–shadow-color);
flex: 1; /* Equal width */
min-width: 180px; /* Minimum width */
}
.intermediate-results div strong {
display: block;
font-size: 1.2em;
color: var(–primary-color);
margin-bottom: 5px;
}
.intermediate-results div span {
font-size: 1.1em;
font-weight: bold;
}
.formula-explanation {
margin-top: 20px;
font-style: italic;
color: #555;
border-top: 1px dashed #ccc;
padding-top: 15px;
text-align: center;
}
table {
width: 100%;
border-collapse: collapse;
margin-top: 25px;
box-shadow: 0 1px 5px var(–shadow-color);
}
th, td {
padding: 12px 15px;
text-align: left;
border-bottom: 1px solid var(–border-color);
}
thead {
background-color: var(–primary-color);
color: white;
}
th {
font-weight: bold;
}
tbody tr:nth-child(even) {
background-color: #f2f2f2;
}
caption {
font-size: 1.1em;
font-weight: bold;
color: var(–primary-color);
margin-bottom: 10px;
caption-side: top;
text-align: left;
}
.chart-container {
margin-top: 30px;
padding: 20px;
background-color: var(–card-bg);
border: 1px solid var(–border-color);
border-radius: 6px;
text-align: center;
}
.chart-container canvas {
max-width: 100%;
height: auto;
}
.chart-legend {
margin-top: 10px;
font-size: 0.9em;
color: #555;
}
.chart-legend span {
margin: 0 10px;
}
.article-content {
margin-top: 30px;
padding: 25px;
border: 1px solid var(–border-color);
border-radius: 6px;
background-color: var(–card-bg);
}
.article-content h2 {
font-size: 2em;
margin-top: 1.5em;
border-bottom: 2px solid var(–primary-color);
padding-bottom: 8px;
}
.article-content h3 {
font-size: 1.5em;
margin-top: 1.2em;
color: #0056b3;
}
.article-content p {
margin-bottom: 1em;
}
.article-content ul, .article-content ol {
margin-left: 20px;
margin-bottom: 1em;
}
.article-content li {
margin-bottom: 0.5em;
}
.article-content .faq-item {
margin-bottom: 1.5em;
padding-bottom: 1em;
border-bottom: 1px dashed #eee;
}
.article-content .faq-item:last-child {
border-bottom: none;
}
.article-content .faq-question {
font-weight: bold;
color: var(–primary-color);
margin-bottom: 0.5em;
}
.article-content a {
color: var(–primary-color);
text-decoration: none;
transition: color 0.2s ease;
}
.article-content a:hover {
color: #003b7d;
text-decoration: underline;
}
.internal-links-section {
margin-top: 30px;
padding: 25px;
border: 1px solid var(–border-color);
border-radius: 6px;
background-color: var(–card-bg);
}
.internal-links-section h2 {
margin-top: 0;
font-size: 1.8em;
color: var(–primary-color);
border-bottom: 2px solid var(–primary-color);
padding-bottom: 10px;
display: inline-block;
}
.internal-links-section ul {
list-style: none;
padding: 0;
}
.internal-links-section li {
margin-bottom: 10px;
}
.internal-links-section li a {
font-weight: bold;
}
.internal-links-section p {
font-size: 0.9em;
color: #555;
margin-left: 5px;
}
@media (max-width: 768px) {
.container {
margin: 10px;
padding: 15px;
}
header h1 {
font-size: 1.8em;
}
.calculator-section, .results-container, .article-content, .internal-links-section {
padding: 15px;
}
.button-group button, .button-group input[type=”button”] {
width: 100%; /* Full width on smaller screens */
min-width: unset;
margin-bottom: 10px; /* Add bottom margin */
}
.button-group {
flex-direction: column; /* Stack buttons vertically */
align-items: center; /* Center buttons */
}
.intermediate-results div {
width: 100%; /* Full width for intermediate results */
min-width: unset;
}
.chart-container {
padding: 15px 0;
}
}

Accurate Calculation for Molar Mass, Stoichiometry, and Chemical Formulas

Chemical Weight Calculator

Calculate the molar mass of a chemical compound or the mass of reactants/products using stoichiometry.

{primary_keyword} is a fundamental concept in chemistry that allows us to quantify the mass of chemical substances. It primarily involves determining the molar mass of a compound, which is the mass of one mole of that substance, and then using this value for stoichiometric calculations to find the mass of reactants or products in a chemical reaction, or to convert between mass and moles. This process is crucial for accurate experimental design, quantitative analysis, and understanding chemical processes at a macroscopic level. Understanding {primary_keyword} is essential for anyone working with chemicals, from students in introductory chemistry to research scientists in pharmaceuticals, materials science, and environmental analysis.

Who Should Use {primary_keyword} Calculations?

• Chemistry Students: Essential for coursework, lab experiments, and understanding chemical reactions.
• Researchers: For preparing solutions, quantifying reactions, and analyzing chemical yields.
• Pharmacists & Pharmaceutical Technicians: Calculating drug dosages and compound synthesis.
• Materials Scientists: Designing and analyzing new materials with specific compositions.
• Environmental Chemists: Assessing the concentration of pollutants or the mass of substances in environmental samples.
• Food Scientists: Analyzing nutritional content and developing new food products.

Common Misconceptions about {primary_keyword}

• Confusing Atomic Weight with Molar Mass: Atomic weight is the mass of a single atom, while molar mass is the mass of one mole (approximately 6.022 x 10^23 particles) of a substance. Molar mass is numerically equivalent to atomic or molecular weight but expressed in grams per mole (g/mol).
• Assuming Uniformity of Elements: The atomic weights used are averages, accounting for natural isotopic abundance. Individual atoms of an element can have slightly different masses.
• Ignoring Stoichiometry for Simple Conversions: While converting moles to grams uses the molar mass directly, more complex scenarios in reactions require understanding mole ratios (stoichiometry) to correctly relate the mass of one substance to another.
• Underestimating the Impact of Hydration: Water molecules incorporated into crystal structures (hydrates) significantly add to the total molar mass. For example, CuSO4 is different from CuSO4·5H2O.

{primary_keyword} Formula and Mathematical Explanation

The core of {primary_keyword} involves two primary calculations: determining the molar mass of a compound and then applying it to find unknown quantities (mass or moles) in a chemical context.

1. Calculating Molar Mass (M)

The molar mass (M) of a chemical compound is the sum of the atomic weights of all atoms present in its chemical formula. To calculate it, you need a periodic table to find the atomic weight of each element.

Formula:

M = ∑ (n_i × AW_i)

Where:

• M = Molar Mass of the compound (g/mol)
• n_i = Number of atoms of element ‘i’ in the chemical formula
• AW_i = Atomic Weight of element ‘i’ (amu, numerically equivalent to g/mol)

2. Stoichiometric Calculations (Mass-Mole Conversions)

Once the molar mass (M) is known, we can convert between mass (m) and moles (n) using the following relationships:

To find Mass (m) from Moles (n):

m = n × M

To find Moles (n) from Mass (m):

n = m / M

Variable Explanations & Table

Here’s a breakdown of the variables involved in {primary_keyword}:

Variables in Chemical Weight Calculation

Variable	Meaning	Unit	Typical Range / Notes
M (Molar Mass)	Mass of one mole of a substance	g/mol	Varies greatly; e.g., H2 ≈ 2 g/mol, C6H12O6 ≈ 180 g/mol, complex proteins can be thousands g/mol
n (Moles)	Amount of substance	mol	Typically positive; 0.001 mol (millimole) to several moles are common in labs. Can be fractional.
m (Mass)	The actual weight of the substance	g (grams)	Typically positive; ranging from milligrams (mg) to kilograms (kg) depending on the scale.
ni (Atom Count)	Number of atoms of a specific element in a molecule	Unitless	Positive integers (e.g., 2 in H2O, 6 in C6H12O6). For polyatomic ions in parentheses, multiply.
AWi (Atomic Weight)	Average mass of atoms of an element	amu or g/mol	Found on the periodic table; e.g., H ≈ 1.008, C ≈ 12.011, O ≈ 15.999, Na ≈ 22.990

Practical Examples (Real-World Use Cases)

Example 1: Calculating the Mass of Water Produced

Consider the reaction for forming water: 2H₂ + O₂ → 2H₂O. If a chemist starts with 5 moles of oxygen gas (O₂), how many grams of water (H₂O) can be produced?

Step 1: Find the Molar Mass of H₂O.

• Atomic Weight of H = 1.008 g/mol
• Atomic Weight of O = 15.999 g/mol
• Molar Mass (H₂O) = (2 × 1.008 g/mol) + (1 × 15.999 g/mol) = 2.016 + 15.999 = 18.015 g/mol

Step 2: Determine Moles of H₂O produced.

From the balanced equation, 1 mole of O₂ produces 2 moles of H₂O. Therefore, 5 moles of O₂ will produce:

Moles of H₂O = 5 mol O₂ × (2 mol H₂O / 1 mol O₂) = 10 moles of H₂O

Step 3: Calculate the Mass of H₂O.

Mass = Moles × Molar Mass

Mass of H₂O = 10 mol × 18.015 g/mol = 180.15 grams

Calculator Usage:

• Formula: H2O
• Quantity: 5
• Quantity Type: Moles
• Expected Result (Molar Mass): ~18.015 g/mol
• Expected Result (Calculated Mass): ~180.15 g
• Expected Result (Calculated Moles): 10 mol (if input was mass of O2)

Interpretation: To produce 180.15 grams of water, assuming complete reaction and sufficient hydrogen, you would need to start with 5 moles of oxygen gas.

Example 2: Finding Moles of Sodium Chloride (NaCl) from its Mass

A chemist has 116.89 grams of pure sodium chloride (table salt). How many moles of NaCl does this represent?

Step 1: Find the Molar Mass of NaCl.

• Atomic Weight of Na = 22.990 g/mol
• Atomic Weight of Cl = 35.453 g/mol
• Molar Mass (NaCl) = (1 × 22.990 g/mol) + (1 × 35.453 g/mol) = 58.443 g/mol

Step 2: Calculate the Moles of NaCl.

Moles = Mass / Molar Mass

Moles of NaCl = 116.89 g / 58.443 g/mol ≈ 2.00 moles

Calculator Usage:

• Formula: NaCl
• Quantity: 116.89
• Quantity Type: Mass (grams)
• Expected Result (Molar Mass): ~58.443 g/mol
• Expected Result (Calculated Mass): 116.89 g (if input was moles)
• Expected Result (Calculated Moles): ~2.00 mol

Interpretation: 116.89 grams of sodium chloride is equivalent to approximately 2.00 moles of NaCl.

How to Use This {primary_keyword} Calculator

1. Enter the Chemical Formula: Accurately type the chemical formula of the substance you are interested in. Use standard notation, including parentheses for polyatomic ions (e.g., Ca(NO₃)₂) and subscripts where applicable (e.g., H₂O). The calculator will parse common formats.
2. Input the Known Quantity: Enter the numerical value of the amount you know. This could be the number of moles or the mass in grams.
3. Select Quantity Type: Choose whether the number you entered in Step 2 represents ‘Moles’ or ‘Mass (grams)’. This tells the calculator what value is provided.
4. Click ‘Calculate’: The calculator will process your inputs.

Reading the Results

• Primary Highlighted Result: This will display either the calculated mass (if you input moles) or the calculated moles (if you input mass). It’s the primary answer based on your input and selection.
• Molar Mass: Shows the calculated molar mass of the compound you entered. This is a key intermediate value used in the calculation.
• Calculated Mass / Calculated Moles: Depending on your input type, one of these fields will display the converted value. The other will be redundant to your input but shows the relationship.
• Chart: Visualizes how much each element contributes to the total molar mass, helping understand the composition.

Decision-Making Guidance

Use this calculator to quickly verify calculations for lab preparations, understand reaction stoichiometry, or convert between different units of chemical amount. If you are planning an experiment, ensure your calculated masses or moles are practical to measure with your available equipment.

For example, if the calculator shows you need 150 grams of a substance, but your smallest available balance measures in increments of 1 gram, you might need to adjust your experimental scale or use a more precise balance. Similarly, if you need to react 0.002 moles of a reagent, you’ll need to calculate the corresponding mass to weigh it out accurately.

Key Factors That Affect {primary_keyword} Results

While the core calculations are straightforward, several factors can influence the accuracy and interpretation of {primary_keyword} results:

1. Accuracy of Atomic Weights: The atomic weights obtained from the periodic table are averages of naturally occurring isotopes. For highly specialized or isotopic analysis, more precise values might be needed. However, for general purposes, standard values are sufficient.
2. Purity of the Substance: The calculations assume the substance is 100% pure. Impurities will alter the actual mass per mole. If you are working with an impure sample, the calculated mass or moles will not reflect the true amount of the desired compound. This is critical in [pharmaceutical applications]() where purity is paramount.
3. Presence of Hydration: Many ionic compounds form hydrates, incorporating water molecules into their crystal structure (e.g., CuSO₄·5H₂O). Failing to account for the mass of these water molecules will lead to incorrect molar mass and subsequent calculations. Always check if the compound is a hydrate.
4. Isotopic Abundance: While standard atomic weights account for natural isotopic variations, if you are working with specific isotopes (e.g., in nuclear chemistry or advanced tracer studies), you would need to use the exact mass of that specific isotope, not the average atomic weight.
5. Temperature and Pressure (for Gases): While molar mass itself is independent of T and P, the *density* and *volume* of gases are highly dependent on these factors (via the Ideal Gas Law, PV=nRT). If you are given the volume of a gas and need to find its mass, you must first use T and P to calculate the moles. This is a common consideration in [gas stoichiometry calculations]().
6. Balancing of Chemical Equations: For calculations involving reactants and products (stoichiometry beyond simple mass-mole conversion), the chemical equation *must* be correctly balanced. An unbalanced equation provides incorrect mole ratios, leading to flawed predictions of reaction yields or required reactant quantities. Proper [stoichiometric analysis]() is key.
7. Significant Figures: Experimental measurements and atomic weights have limited significant figures. Ensure your final answer reflects the appropriate number of significant figures based on the least precise input value or atomic weight used. This impacts the reliability of [quantitative chemistry]() results.

Frequently Asked Questions (FAQ)

Q1: What is the difference between molecular weight and molar mass?

A1: Molecular weight is the sum of the atomic weights of atoms in a molecule, expressed in atomic mass units (amu). Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). Numerically, they are identical for a given substance, but they represent different concepts (mass of a single particle vs. mass of a mole of particles).

Q2: Can I use this calculator for ionic compounds like NaCl?

A2: Yes, absolutely. For ionic compounds, we typically refer to the ‘formula mass’ or ‘molar mass’ of the formula unit, calculated the same way as molecular weight/molar mass by summing the atomic weights of the constituent elements in the correct ratio (e.g., 1 Na and 1 Cl for NaCl).

Q3: How do I handle chemical formulas with parentheses, like Ca(NO₃)₂?

A3: The calculator is designed to parse these. For Ca(NO₃)₂, it means there is 1 Calcium (Ca) atom, 2 Nitrogen (N) atoms (1 inside the parenthesis × 2 outside), and 6 Oxygen (O) atoms (3 inside × 2 outside). The calculator sums the atomic weights accordingly.

Q4: What if the chemical is a hydrate, like Copper(II) sulfate pentahydrate (CuSO₄·5H₂O)?

A4: You should include the water molecules in the formula. For CuSO₄·5H₂O, you would calculate the molar mass of CuSO₄ and add 5 times the molar mass of H₂O. A simplified entry might be CuSO4(H2O)5, but it’s best to be explicit if the calculator allows separate components or check compound databases.

Q5: My calculation resulted in ‘NaN’. What went wrong?

A5: ‘NaN’ (Not a Number) usually indicates an invalid input. Check if you entered non-numeric values in quantity fields, or if the chemical formula was entered in an unrecognized format. Ensure all numerical inputs are valid numbers and that the formula is correctly written.

Q6: How precise are the atomic weights used?

A6: The calculator uses standard, rounded atomic weights commonly found on most periodic tables (typically to 3 decimal places). For most general chemistry applications, this precision is sufficient. If extreme precision is needed for specialized research, you might need to consult more detailed isotopic data.

Q7: Can this calculator help with reaction yields?

A7: Indirectly. It helps you calculate the theoretical mass of a product based on reactant moles, or vice versa. To determine percent yield, you would compare your experimentally obtained mass to the theoretical mass calculated using stoichiometry (which relies on molar mass calculations).

Q8: Why is {primary_keyword} important in fields like drug development?

A8: In [drug development]() and [pharmaceutical manufacturing](), precise dosing and synthesis are critical. {primary_keyword} calculations ensure that the correct amounts of active ingredients and reagents are used, guaranteeing drug efficacy, safety, and consistent product quality. Small errors in mass calculation can lead to ineffective or even harmful medications.

Related Tools and Internal Resources

• <a href="”>Pharmaceutical Applications of Chemical Calculations

  Learn how precise chemical weight calculations ensure drug efficacy and safety.

• <a href="”>Stoichiometry Calculations for Gases

  Explore advanced methods for calculating with gaseous reactants and products.

• <a href="”>Advanced Stoichiometric Analysis Techniques

  Deep dive into complex reaction calculations and limiting reactants.

• <a href="”>Principles of Quantitative Chemistry

  Understand the foundational concepts and methods used in quantitative chemical analysis.

• <a href="”>Chemical Calculations in Drug Discovery

  See how molar mass and stoichiometry play roles from initial discovery to clinical trials.

• <a href="”>Quality Control in Pharmaceutical Manufacturing

  Discover the importance of accurate measurements and calculations in producing safe medicines.

// Atomic weights (approximate, common values)
var atomicWeights = {
‘H’: 1.008, ‘He’: 4.003, ‘Li’: 6.94, ‘Be’: 9.012, ‘B’: 10.81, ‘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’: 28.085, ‘P’: 30.974, ‘S’: 32.06, ‘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, ‘Ni’: 58.693, ‘Co’: 58.933, ‘Cu’: 63.546, ‘Zn’: 65.38,
‘Ga’: 69.723, ‘Ge’: 72.63, ‘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’: 102.91, ‘Pd’: 106.42, ‘Ag’: 107.87, ‘Cd’: 112.41, ‘In’: 114.82, ‘Sn’: 118.71,
‘Sb’: 121.76, ‘Te’: 127.60, ‘I’: 126.90, ‘Xe’: 131.29, ‘Cs’: 132.91, ‘Ba’: 137.33, ‘La’: 138.91, ‘Ce’: 140.12, ‘Pr’: 140.91, ‘Nd’: 144.24,
‘Pm’: 145.0, ‘Sm’: 150.36, ‘Eu’: 151.96, ‘Gd’: 157.25, ‘Tb’: 158.93, ‘Dy’: 162.50, ‘Ho’: 164.93, ‘Er’: 167.26, ‘Tm’: 168.93, ‘Yb’: 173.05, ‘Lu’: 174.97,
‘Hf’: 178.49, ‘Ta’: 180.95, ‘W’: 183.84, ‘Re’: 186.21, ‘Os’: 190.23, ‘Ir’: 192.22, ‘Pt’: 195.08, ‘Au’: 196.97, ‘Hg’: 200.59, ‘Tl’: 204.38,
‘Pb’: 207.2, ‘Bi’: 208.98, ‘Po’: 209.0, ‘At’: 210.0, ‘Rn’: 222.0, ‘Fr’: 223.0, ‘Ra’: 226.0, ‘Ac’: 227.0, ‘Th’: 232.04, ‘Pa’: 231.04, ‘U’: 238.03
};

var chartInstance = null;

function parseChemicalFormula(formula) {
var elementCounts = {};
var regex = /([A-Z][a-z]*)(\d*)|(\()|(\))/g;
var match;
var currentMultiplier = [1]; // Stack for handling parentheses

while ((match = regex.exec(formula)) !== null) {
if (match[3] === ‘(‘) { // Opening parenthesis
currentMultiplier.push(currentMultiplier[currentMultiplier.length – 1]);
} else if (match[4] === ‘)’) { // Closing parenthesis
if (currentMultiplier.length > 1) {
currentMultiplier.pop();
}
} else { // Element and its count
var element = match[1];
var count = match[2] ? parseInt(match[2], 10) : 1;
var effectiveCount = count * currentMultiplier[currentMultiplier.length – 1];

if (elementCounts.hasOwnProperty(element)) {
elementCounts[element] += effectiveCount;
} else {
elementCounts[element] = effectiveCount;
}
}
}
return elementCounts;
}

function calculateMolarMass(formula) {
var elementCounts = parseChemicalFormula(formula);
var molarMass = 0;
var contributions = {};
var isValidFormula = true;

for (var element in elementCounts) {
if (atomicWeights.hasOwnProperty(element)) {
var weight = atomicWeights[element];
var count = elementCounts[element];
var contribution = weight * count;
molarMass += contribution;
contributions[element] = contribution;
} else {
isValidFormula = false;
break; // Element not found
}
}

if (!isValidFormula) {
return { molarMass: NaN, contributions: {}, error: “Unknown element in formula.” };
}
if (molarMass === 0 && Object.keys(elementCounts).length > 0) {
return { molarMass: NaN, contributions: {}, error: “Formula parsed but resulted in zero mass. Check formula syntax.” };
}
if (Object.keys(elementCounts).length === 0 && formula.trim() !== “”) {
return { molarMass: NaN, contributions: {}, error: “Could not parse the provided formula.” };
}

return { molarMass: molarMass, contributions: contributions, error: null };
}

function calculateChemicalWeight() {
var formulaInput = document.getElementById(‘chemicalFormula’);
var quantityInput = document.getElementById(‘quantity’);
var quantityTypeSelect = document.getElementById(‘quantityType’);

var formula = formulaInput.value.trim();
var quantity = parseFloat(quantityInput.value);
var quantityType = quantityTypeSelect.value;

// — Input Validation —
document.getElementById(‘chemicalFormulaError’).innerText = ”;
document.getElementById(‘quantityError’).innerText = ”;

var formulaIsValid = formula.length > 0;
var quantityIsValid = !isNaN(quantity) && quantity >= 0;

if (!formulaIsValid) {
document.getElementById(‘chemicalFormulaError’).innerText = ‘Chemical formula cannot be empty.’;
}
if (!quantityIsValid) {
document.getElementById(‘quantityError’).innerText = ‘Quantity must be a non-negative number.’;
}

if (!formulaIsValid || !quantityIsValid) {
// Reset results if validation fails
document.getElementById(‘primaryResult’).innerText = ‘–‘;
document.getElementById(‘molarMassValue’).innerText = ‘–‘;
document.getElementById(‘calculatedMassValue’).innerText = ‘–‘;
document.getElementById(‘calculatedMolesValue’).innerText = ‘–‘;
if (chartInstance) {
chartInstance.destroy();
chartInstance = null;
document.getElementById(‘chartLegend’).innerHTML = ”;
}
return;
}

var calculationResult = calculateMolarMass(formula);

if (calculationResult.error) {
document.getElementById(‘chemicalFormulaError’).innerText = calculationResult.error;
document.getElementById(‘primaryResult’).innerText = ‘–‘;
document.getElementById(‘molarMassValue’).innerText = ‘–‘;
document.getElementById(‘calculatedMassValue’).innerText = ‘–‘;
document.getElementById(‘calculatedMolesValue’).innerText = ‘–‘;
if (chartInstance) {
chartInstance.destroy();
chartInstance = null;
document.getElementById(‘chartLegend’).innerHTML = ”;
}
return;
}

var molarMass = calculationResult.molarMass;
var contributions = calculationResult.contributions;

document.getElementById(‘molarMassValue’).innerText = molarMass.toFixed(3); // Display molar mass

var calculatedMass = ‘–‘;
var calculatedMoles = ‘–‘;
var primaryResultText = ‘–‘;

if (quantityType === ‘moles’) {
calculatedMoles = quantity.toFixed(5); // Show input moles
calculatedMass = (quantity * molarMass).toFixed(5); // Calculate mass
primaryResultText = calculatedMass + ” g”;
} else { // mass_g
calculatedMass = quantity.toFixed(5); // Show input mass
calculatedMoles = (quantity / molarMass).toFixed(5); // Calculate moles
primaryResultText = calculatedMoles + ” mol”;
}

document.getElementById(‘calculatedMassValue’).innerText = calculatedMass;
document.getElementById(‘calculatedMolesValue’).innerText = calculatedMoles;
document.getElementById(‘primaryResult’).innerText = primaryResultText;

// — Chart Update —
updateChart(contributions, molarMass);
}

function updateChart(contributions, totalMolarMass) {
var ctx = document.getElementById(‘molarMassChart’).getContext(‘2d’);

// Destroy previous chart instance if it exists
if (chartInstance) {
chartInstance.destroy();
}

if (totalMolarMass === 0 || isNaN(totalMolarMass)) {
if (ctx) {
ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height); // Clear canvas
}
document.getElementById(‘chartLegend’).innerHTML = ‘No data to display chart.’;
return;
}

var labels = [];
var data = [];
var colors = [‘#004a99’, ‘#28a745’, ‘#ffc107’, ‘#17a2b8’, ‘#6f42c1’, ‘#d63384’, ‘#fd7e14’, ‘#20c997’]; // Primary and distinct colors
var legendHtml = ”;

// Sort contributions for consistent chart order
var sortedContributions = Object.entries(contributions).sort(([,a],[,b]) => b-a);

sortedContributions.forEach(function(item, index) {
var element = item[0];
var contribution = item[1];
var percentage = (contribution / totalMolarMass) * 100;
labels.push(element);
data.push(percentage.toFixed(1)); // Store percentage for chart data

var colorIndex = index % colors.length;
legendHtml += ‘• ‘ + element + ‘ (‘ + percentage.toFixed(1) + ‘%) ‘;
});

document.getElementById(‘chartLegend’).innerHTML = legendHtml;

chartInstance = new Chart(ctx, {
type: ‘pie’, // Changed to Pie chart for composition
data: {
labels: labels,
datasets: [{
label: ‘Molar Mass Contribution (%)’,
data: data,
backgroundColor: colors.slice(0, labels.length), // Use colors, cycle if needed
borderColor: ‘#ffffff’,
borderWidth: 1
}]
},
options: {
responsive: true,
maintainAspectRatio: true, // Allow chart to resize appropriately
plugins: {
legend: {
display: false // Legend handled manually for better control
},
tooltip: {
callbacks: {
label: function(context) {
var label = context.label || ”;
if (label) {
label += ‘: ‘;
}
if (context.parsed !== null) {
label += context.parsed + ‘%’;
}
return label;
}
}
}
}
}
});
}

function resetCalculator() {
document.getElementById(‘chemicalFormula’).value = ‘H2O’;
document.getElementById(‘quantity’).value = ‘1’;
document.getElementById(‘quantityType’).value = ‘moles’;
document.getElementById(‘chemicalFormulaError’).innerText = ”;
document.getElementById(‘quantityError’).innerText = ”;
calculateChemicalWeight(); // Recalculate with defaults
}

function copyResults() {
var primaryResult = document.getElementById(‘primaryResult’).innerText;
var molarMass = document.getElementById(‘molarMassValue’).innerText;
var calculatedMass = document.getElementById(‘calculatedMassValue’).innerText;
var calculatedMoles = document.getElementById(‘calculatedMolesValue’).innerText;
var formula = document.getElementById(‘chemicalFormula’).value;
var quantity = document.getElementById(‘quantity’).value;
var quantityType = document.getElementById(‘quantityType’).options[document.getElementById(‘quantityType’).selectedIndex].text;

var contentToCopy = “Chemical Weight Calculation Results:\n”;
contentToCopy += “———————————-\n”;
contentToCopy += “Formula: ” + formula + “\n”;
contentToCopy += “Input Quantity (” + quantityType + “): ” + quantity + “\n”;
contentToCopy += “———————————-\n”;
contentToCopy += “Primary Result: ” + primaryResult + “\n”;
contentToCopy += “Molar Mass: ” + molarMass + ” g/mol\n”;
if (document.getElementById(‘quantityType’).value === ‘moles’) {
contentToCopy += “Calculated Mass: ” + calculatedMass + ” g\n”;
contentToCopy += “Input Moles: ” + calculatedMoles + ” mol\n”;
} else {
contentToCopy += “Calculated Moles: ” + calculatedMoles + ” mol\n”;
contentToCopy += “Input Mass: ” + calculatedMass + ” g\n”;
}
contentToCopy += “———————————-\n”;
contentToCopy += “Key Assumptions:\n”;
contentToCopy += “- Standard atomic weights used.\n”;
contentToCopy += “- Assumes 100% purity of the compound.\n”;
contentToCopy += “- Hydrates not explicitly accounted for unless included in formula.\n”;

navigator.clipboard.writeText(contentToCopy).then(function() {
// Optional: Provide user feedback
var copyButton = document.querySelector(‘.copy-btn’);
var originalText = copyButton.innerText;
copyButton.innerText = ‘Copied!’;
setTimeout(function() {
copyButton.innerText = originalText;
}, 2000);
}).catch(function(err) {
console.error(‘Failed to copy text: ‘, err);
// Optional: Provide user feedback for failure
});
}

// Initial calculation on page load
document.addEventListener(‘DOMContentLoaded’, function() {
// Ensure Chart.js is loaded before trying to use it
if (typeof Chart === ‘undefined’) {
console.error(“Chart.js not loaded. Please ensure it’s included in your HTML.”);
// Provide a fallback message
document.getElementById(‘chartLegend’).innerHTML = ‘Chart library not available.’;
return;
}
resetCalculator(); // Load with default values
});

// Add Chart.js script dynamically if not present
if (typeof Chart === ‘undefined’) {
var script = document.createElement(‘script’);
script.src = ‘https://cdn.jsdelivr.net/npm/chart.js@3.7.0/dist/chart.min.js’; // Use a specific version
script.onload = function() {
// Re-run initial calculation now that Chart.js is loaded
document.addEventListener(‘DOMContentLoaded’, function() {
resetCalculator();
});
};
script.onerror = function() {
console.error(“Failed to load Chart.js from CDN.”);
document.getElementById(‘chartLegend’).innerHTML = ‘Error loading chart resources.’;
};
document.head.appendChild(script);
}