Molar MassMolar mass of phenol (C6H5OH)
The molar mass of phenol, C6H5OH, is 94.11 g/mol. One mole of it, which is 6.022 × 1023 molecules, has a mass of 94.11 grams.
94.11 g/mol
6 × 12.011 + 6 × 1.0080 + 15.999 = 94.113 · 13 atoms in the formula · also called carbolic acid
About phenol
Phenol is a benzene ring carrying an OH group. It was the first surgical antiseptic and is used to make plastics.
Other names: carbolic acid.
The working
The formula C6H5OH has 6 carbon atoms, 6 hydrogen atoms and 1 oxygen atom, 13 atoms in all. Multiply each count by the atomic weight of the element and add:
| Element | Atoms | Atomic weight | Total | Share by mass |
|---|---|---|---|---|
| Carbon (C) | 6 | 12.011 | 72.066 | 76.57% |
| Hydrogen (H) | 6 | 1.0080 | 6.048 | 6.43% |
| Oxygen (O) | 1 | 15.999 | 15.999 | 17.00% |
6 × 12.011 + 6 × 1.0080 + 15.999 = 94.113 g/mol
With the rounded atomic masses used in many school books (C = 12, H = 1, O = 16) the answer is 94 g/mol. The difference from 94.11 is too small to matter in most school sums.
Percentage composition
By mass, C6H5OH is 76.57% carbon, 6.43% hydrogen and 17.00% oxygen. The largest share comes from carbon. In a 100 g sample there are 76.6 g of carbon, 6.4 g of hydrogen and 17.0 g of oxygen.
Worked examples
Grams to moles. How many moles are in 10 g of C6H5OH? Divide the mass by the molar mass: 10 ÷ 94.11 = 0.1063 mol.
Moles to grams. What is the mass of 1.5 mol of C6H5OH? Multiply: 1.5 × 94.11 = 141.2 g.
Counting particles. 10 g contains 0.1063 mol × 6.022 × 1023 = 6.399 × 1022 molecules, and 8.318 × 1023 atoms in all.
Quick conversion tables
| Amount | Mass |
|---|---|
| 0.1 mol | 9.411 g |
| 0.5 mol | 47.06 g |
| 1 mol | 94.11 g |
| 2 mol | 188.2 g |
| 5 mol | 470.6 g |
| Mass | Moles |
|---|---|
| 1 g | 0.01063 mol |
| 10 g | 0.1063 mol |
| 100 g | 1.063 mol |
| 1 kg | 10.63 mol |
For other amounts use the grams and moles converter.
Questions people ask
What is the molar mass of C6H5OH?
The molar mass of phenol (C6H5OH) is 94.11 g/mol, or 94.113 g/mol before rounding, using IUPAC abridged atomic weights.
How many moles are in 100 g of C6H5OH?
100 ÷ 94.11 = 1.063 mol.
What is the mass of one molecule of C6H5OH?
Divide the molar mass by the Avogadro constant: 94.11 ÷ 6.022 × 1023 = 1.563 × 10-22 g.
What is the percentage of carbon in C6H5OH?
Carbon makes up 76.57% of the mass of C6H5OH: 6 × 12.011 ÷ 94.113 × 100.
Which values? This site uses the abridged standard atomic weights published by IUPAC (CIAAW), read on 12 November 2026. Your textbook or question paper may round them differently, for example H = 1 and O = 16, so its answer can differ slightly. In an exam, use the values the paper gives.