Final answer:
The formula mass of C6H12O6 is 180.156 amu, calculated by adding together the atomic masses of carbon, hydrogen, and oxygen in the molecule.
Step-by-step explanation:
The formula mass of C6H12O6 is calculated by summing the atomic masses of all the atoms present in the formula. To find the formula mass to five significant figures, we use the average atomic masses for carbon (C), hydrogen (H), and oxygen (O) as follows:
- C: 12.011 amu (6 atoms)
- H: 1.008 amu (12 atoms)
- O: 15.999 amu (6 atoms)
C6H12O6 formula mass = (6 × 12.011) + (12 × 1.008) + (6 × 15.999) = 72.066 + 12.096 + 95.994 = 180.156 amu (rounded to five significant figures).
Note that this same calculation approach can be applied for determining the molar mass in grams per mole (g/mol), as one mole of a substance will have a mass in grams equal to the formula mass in amu.