Molar mass of glucose
The molar mass of glucose (C₆H₁₂O₆) is 180.156 g/mol: the sum of the atomic weights 6 × 12.011 + 12 × 1.0080 + 6 × 15.999. School problems round it to 180 g/mol (C = 12, H = 1, O = 16).
Breakdown by element
M(C6H12O6) = 6 × 12.011 + 12 × 1.0080 + 6 × 15.999 = 180.156 g/mol
The result is rounded to the precision of the least precise atomic weight. Atomic weights from IUPAC (CIAAW). Agrees with PubChem: 180.16 g/mol. PubChem CID 5793
What is glucose?
Glucose (grape sugar, dextrose) is a white, sweet crystalline substance and the most common simple sugar. Plants make it from carbon dioxide and water by photosynthesis.
Glucose is the main source of energy for the body’s cells; its level in the blood is what “blood sugar” means. Starch and cellulose are built from glucose molecules.
Properties
- State at 25 °C
- Solid
- Density
- 1.54 g/cm³
- Melting point
- 146 °C α-D-glucose
- Solubility in water
- soluble
Sources: PubChem (HSDB, NIOSH), Wikipedia (CRC Handbook), NIST Chemistry WebBook; each value agrees in two of them.
Molar mass problems with glucose
For school problems (C = 12, H = 1, O = 16): M(C₆H₁₂O₆) = 180 g/mol
Problem 1
How many moles are in 540 g of C₆H₁₂O₆?
n = m ÷ M = 540 g ÷ 180 g/mol
Answer: 3 mol
Problem 2
What is the mass of 1.5 mol of C₆H₁₂O₆?
m = n × M = 1.5 mol × 180 g/mol
Answer: 270 g
Problem 3
What is the mass percentage of C in C₆H₁₂O₆?
w(C) = 6 × M(C) ÷ M(C₆H₁₂O₆) = 6 × 12 ÷ 180 = 0.4
Answer: 40.0%
Problem 4
How many molecules are in 0.1 mol of C₆H₁₂O₆?
N = n × NA = 0.1 mol × 6.02 × 10²³ mol⁻¹
Answer: 6.02 × 10²²
Common substances
What is molar mass?
Molar mass M is the mass of one mole of a substance, about 6.022 × 10²³ of its particles. It is measured in grams per mole (g/mol).
To find it, add up the atomic weights of all the atoms in the formula: multiply each element’s atomic weight by its subscript, the number of its atoms. In g/mol, the molar mass equals the relative molecular mass Mr.
For water: M(H₂O) = 2 × 1.0080 + 15.999 = 18.015 g/mol.