The molar mass of fructose (C6H12O6) is 180.156 g/mol.
Case matters: CO is carbon monoxide, Co is
cobalt. Brackets and hydrates are fine — try
or
.
| Element | Atoms | Atomic mass | Mass contributed | Percent |
|---|---|---|---|---|
| Carbon (C) | 6 | 12.011 | 72.066 | 40.00% |
| Hydrogen (H) | 12 | 1.0080 | 12.096 | 6.72% |
| Oxygen (O) | 6 | 15.999 | 95.994 | 53.28% |
| Total | 24 | 180.156 | 100.00% |
72.066 + 12.096 + 95.994 = 180.156 g/mol
Grams and moles
25 g of fructose is 0.1388 mol, because 25 ÷ 180.156 = 0.1388.
These elements have no single atomic weight. Their isotopic mix varies slightly depending on where on Earth the sample came from, so the figure used here is the conventional value IUPAC publishes for when one number is needed: carbon is 12.011, and really lies between 12.0096 and 12.0116; hydrogen is 1.0080, and really lies between 1.00784 and 1.00811; oxygen is 15.999, and really lies between 15.99903 and 15.99977.
Fructose weighs 180.156 g/mol, the identical figure to glucose, because the formulas are identical. The two are isomers built from the same six carbons, twelve hydrogens and six oxygens, connected differently. Glucose closes into a six-membered ring, fructose into a five-membered one.
Weighing cannot tell them apart, and neither can elemental analysis, since the percent compositions match as well: the same 53.28% oxygen and 40.00% carbon, with hydrogen making up the remaining 6.72%. Everything that distinguishes them is structural, and the consequences are not subtle. Fructose tastes roughly twice as sweet, it is absorbed differently, and the liver processes it by a separate route.
Galactose is a third isomer with the same numbers again.
High-fructose corn syrup is mostly a mixture of free glucose and free fructose, while table sugar is the two bonded together as sucrose. Since sucrose splits into exactly those two sugars during digestion, the eventual molar quantities absorbed are close, and the argument between them turns on rate rather than on mass.