Calculated Result
Results update below the header and above the form after submission.
Calculator Inputs
Plotly Graph
The chart compares the main outputs on a logarithmic axis so very large particle counts remain readable.
Formula Used
effective mass = sample mass × purity / 100
moles = effective mass / molar mass
entities = moles × Avogadro constant
target atoms = entities × atoms per molecule
This workflow converts a known mass into moles first, then into molecules or formula units, then into the requested number of atoms.
How to Use This Calculator
- Enter the sample mass in grams.
- Enter the compound molar mass in grams per mole.
- Set how many target atoms exist in one molecule or formula unit.
- Adjust purity if the sample is not fully pure.
- Choose the displayed significant figures.
- Click Calculate to show results above the form.
- Review the chart, then export the output as CSV or PDF.
Example Data Table
| Sample | Mass (g) | Molar Mass (g/mol) | Atoms per Entity | Purity (%) | Calculated Atoms |
|---|---|---|---|---|---|
| Water | 18.015 | 18.015 | 3 | 100 | 1.8066 × 1024 |
| Carbon dioxide | 44.010 | 44.010 | 3 | 100 | 1.8066 × 1024 |
| Sodium chloride | 58.440 | 58.440 | 2 | 100 | 1.2044 × 1024 |
| Glucose | 9.000 | 180.156 | 24 | 98 | 7.0764 × 1023 |
FAQs
1. What does g/mol mean?
g/mol means grams per mole. It tells you the mass of one mole of a substance, which links sample mass to the number of particles present.
2. Can this calculator find molecules as well as atoms?
Yes. The calculator first computes moles, then molecules or formula units. It multiplies by atoms per entity afterward, so both levels are available.
3. Why do I need molar mass?
Molar mass converts a measured mass into moles. Without it, grams cannot be translated correctly into molecules or atoms.
4. What should I enter for atoms per entity?
Enter the number of target atoms in one molecule or formula unit. For H₂O use 3 total atoms, or use 2 if you only want hydrogen atoms.
5. Does purity affect the result?
Yes. If purity is below 100%, only the pure portion contributes to moles and atoms. This makes mixed or impure samples more realistic.
6. Why are the numbers so large?
Atoms are extremely small, so even tiny laboratory masses contain enormous particle counts. Scientific notation keeps those results readable and easier to compare.
7. Can I use this for ionic compounds?
Yes. For ionic compounds, treat one formula unit like one entity. Then enter the number of atoms you want counted within that formula unit.
8. Is Avogadro’s constant editable?
Yes. It is prefilled with the standard value, but you can edit it if your class, lab sheet, or reference uses a rounded constant.