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

C7H16S2Si

Molecular formula

Molar mass192.41g/mol
Monoisotopic mass192.0463Da
Nominal mass192Da
Rings plus double bonds
1
Details
Monoisotopic mass
192.046269 Da
Average mass, unrounded
192.410000 g/molShown above to 2 decimals, the precision of the least precise standard atomic weight in the formula.
Mass defect
0.0463 Da
Atoms
26

Isotope pattern

M · C7H16S2Si · most intense peak 192.0463

0255075100192193194195196197198192.0463100%193.047914.4%194.042913.2%195.04441.56%%mass (Da)
IonFormulam/z
C7H16S2Si 192.0463
C7H17S2Si+ 193.0535
C7H16NaS2Si+ 215.0355
C7H16KS2Si+ 231.0094
C7H20NS2Si+ 210.0801
C7H18S2Si2+ 97.0304
C7H16S2Si+ 192.0457
C7H15S2Si− 191.0390
C7H16ClS2Si− 227.0157
Peak list
Mass (Da)Relative intensityAbundance
192.04627100.00 %77.0357 %
193.0478914.41 %11.1041 %
194.0428513.16 %10.1407 %
195.044381.56 %1.2028 %
196.039680.602 %0.4641 %
197.041320.057 %0.0436 %
198.037210.011 %0.0083 %

Elemental composition

ElementAtomsMass (g/mol)Mass %
C Carbon784.07743.70
H Hydrogen1616.1288.38
S Sulfur264.12033.32
Si Silicon128.08514.60

Elemental analysis

ElementCalcd (%)Found (%)Δ
C43.70——
H8.38——
S33.32——
Anal. Calcd for C7H16S2Si: C, 43.70; H, 8.38; S, 33.32.
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.