How do I convert between moles, grams and number of molecules?

First get the molar mass from the formula; divide grams by molar mass to find moles, then multiply moles by Avogadro's number (6.022 × 10²³) to find molecules. The tool handles all three conversions automatically.

How is molar mass calculated?

Each element's atomic weight is multiplied by how many atoms of it appear, then all contributions are summed. For H2O this is (2 × 1.008) + 16.00 ≈ 18.02 g/mol.

What does the element composition percentage mean and how do I read it?

It shows each element's percentage by mass in the compound, calculated as that element's mass contribution divided by the molar mass. For water it works out to roughly 88.8% oxygen and 11.2% hydrogen by mass.

Does it support formulas with parentheses like Ca(OH)2?

Yes, the atom count inside the parentheses is multiplied by the outer subscript. Ca(OH)2 contains 1 Ca, 2 O and 2 H, giving a molar mass of about 74.09 g/mol.

Which 10 common compounds are built in and how do they help?

Frequently used compounds like water, carbon dioxide, glucose and salt can be selected with one click, so you can calculate quickly without typing the formula. They serve as a handy starting point for quick checks and learning.

What should I do if I get no result or an error?

The most common cause is a wrong symbol or a lowercase element (e.g. 'h2o' instead of 'H2O') or an unclosed parenthesis. Make sure symbols are capitalized correctly and atom counts come after the symbol.

Can I rely on these values for homework or lab work?

Results use standard atomic weights and are reliable for general use, though rounding may cause small differences. They are for informational purposes; for critical lab or academic work, verify against current IUPAC values.

Mole calculator (chemistry) — Free Online

Chemical Formula

Amount (mol)

Molar Mass

18,015 g/mol

H2: 2,016O: 15,999

Moles (n)

1 mol

Mass

18,015 g

Molecules

6.022e+23

Elemental Composition

H₂Hydrogen2,016 g/mol (11,2%)

OOxygen15,999 g/mol (88,8%)

Common Compounds

H2OWater18,02 g/mol

NaClSalt58,44 g/mol

H2SO4Sulfuric Acid98,08 g/mol

HClHydrochloric Acid36,46 g/mol

NaOHSodium Hydroxide40 g/mol

CO2Carbon Dioxide44,01 g/mol

C6H12O6Glucose180,16 g/mol

CaCO3Calcium Carbonate100,09 g/mol

NH3Ammonia17,03 g/mol

C2H5OHEthanol46,07 g/mol

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Frequently asked questions

Use correct element symbols with proper capitalization and place atom counts right after each symbol, such as H2O, CO2 or C6H12O6. Case matters: 'Co' is cobalt while 'CO' is carbon monoxide.

Mole Calculator (Chemistry)

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