Molar mass

Molar mass, exact mass and elemental composition for any formula, compound or SMILES, with the isotope pattern, HRMS adducts and an elemental analysis check.

Formula or compound

Read as a formula
Examples:

Hydrates with · or *, charges as Fe3+ or SO4{2-}, labelled atoms as [13C] or D.

Molar mass

C6H7Cl3N2

Molecular formula

Molar mass213.49g/mol
Monoisotopic mass211.9675Da
Nominal mass212Da
Rings plus double bonds
3
Details
Monoisotopic mass
211.967481 Da
Average mass, unrounded
213.486000 g/molShown above to 2 decimals, the precision of the least precise standard atomic weight in the formula.
Mass defect
−0.0325 Da
Atoms
18

Isotope pattern

M · C6H7Cl3N2 · most intense peak 211.9675

0255075100212213214215216217218219211.9675100%213.964696.2%215.961630.9%212.97027.3%214.96737.01%217.95883.35%216.96432.25%%mass (Da)
IonFormulam/z
C6H7Cl3N2 211.9675
C6H8Cl3N2+ 212.9748
C6H7Cl3N2Na+ 234.9567
C6H7Cl3KN2+ 250.9306
C6H11Cl3N3+ 230.0013
C6H9Cl3N22+ 106.9910
C6H7Cl3N2+ 211.9669
C6H6Cl3N2− 210.9602
C6H7Cl4N2− 246.9369
Peak list
Mass (Da)Relative intensityAbundance
211.96748100.00 %40.4363 %
212.970247.30 %2.9521 %
213.9645596.22 %38.9067 %
214.967297.01 %2.8353 %
215.9616430.93 %12.5081 %
216.964352.25 %0.9082 %
217.958813.35 %1.3531 %
218.961430.240 %0.0972 %

Elemental composition

ElementAtomsMass (g/mol)Mass %
C Carbon672.06633.76
H Hydrogen77.0563.31
Cl Chlorine3106.35049.82
N Nitrogen228.01413.12

Elemental analysis

ElementCalcd (%)Found (%)Δ
C33.76——
H3.31——
N13.12——
Anal. Calcd for C6H7Cl3N2: C, 33.76; H, 3.31; N, 13.12.
How the masses are calculated

The molar mass sums the IUPAC standard atomic weights, using the conventional value for elements whose weight is given as an interval (hydrogen 1.008, carbon 12.011, sulfur 32.06). It is shown to the number of decimals of the least precise atomic weight in the formula, so CuSO4·5H2O gets two decimals because of sulfur; the unrounded value is under Details.

The monoisotopic mass uses the mass of the most abundant isotope of every element, the nominal mass its mass number. Labelled atoms, written [13C], D or T, count with their own nuclide mass and are taken as fully enriched. For an ion, one electron mass, 0.000 548 579 909 u, is subtracted per positive charge and added per negative charge.

How the isotope pattern is computed

Every element's natural isotope distribution is raised to its atom count by repeated squaring, and the element distributions are then convolved with each other. In centroid mode the isotopologues are grouped by nominal mass and each group is reported at its intensity-weighted mean m/z, which is what a mass spectrometer at ordinary resolution shows; this is exact apart from dropping contributions below 10−12 of the largest. Fine structure keeps isotopologues apart, merges those closer than 0.1 mDa and drops those below 10−8 of the largest, which resolves, for example, 34S from 13C2.

Adduct m/z values follow m/z = (M + adduct − z·me) / |z|. The copy button gives the line in the form the ACS journals print, for example “[M + H]+ Calcd for C8H11N4O2 195.0877”. The ACS guidelines ask that found and calculated m/z agree within 0.003 m/z units, the limit the found m/z check uses.

Elemental analysis

Calculated percentages are mass fractions from the standard atomic weights. Journals ask for found values within ±0.4 % (absolute) of the calculated ones. If a sample holds solvent, enter it as a solvate, for example 0.5 × H2O, and the calculated values are for C8H10N4O2·0.5H2O.

Sources

Standard atomic weights: IUPAC Commission on Isotopic Abundances and Atomic Weights, “Standard atomic weights of the elements 2021”, Pure Appl. Chem. 94, 573 (2022). Isotope masses and natural abundances: NIST, Atomic Weights and Isotopic Compositions for All Elements (Standard Reference Database 144). Electron mass: CODATA 2018, Rev. Mod. Phys. 93, 025010 (2021). Reporting criteria: ACS Author Guidelines for The Journal of Organic Chemistry and Organic Letters.