原子经济性计算器
计算化学反应的原子经济性百分比。
Molecular Weight
180.156 g/mol
Molecular Weight vs Number of Carbon Atoms
公式
## Molecular Weight Calculation The molecular weight (molar mass) of a compound is the sum of the atomic weights of all atoms in its molecular formula. ### Formula **MW = sum(n_i × AW_i)** where n_i is the number of atoms of element i and AW_i is the standard atomic weight. Standard atomic weights: C = 12.011, H = 1.008, O = 15.999, N = 14.007, S = 32.065 g/mol.
计算示例
Calculate the molecular weight of glucose (C6H12O6).
- 01C contribution: 6 × 12.011 = 72.066
- 02H contribution: 12 × 1.008 = 12.096
- 03O contribution: 6 × 15.999 = 95.994
- 04MW = 72.066 + 12.096 + 95.994 = 180.156 g/mol
常见问题
What is the difference between molecular weight and formula weight?
Molecular weight applies to discrete molecules. Formula weight applies to ionic compounds like NaCl, which form lattices rather than molecules. The calculation method is the same.
Why are atomic weights not whole numbers?
Atomic weights reflect the natural isotopic distribution. Carbon is mostly C-12 but contains some C-13, giving an average atomic weight of 12.011. Only pure isotopes have near-integer masses.
How is molecular weight used in lab work?
To convert between moles and grams: grams = moles × MW. To prepare a 1 M solution, dissolve one MW worth of grams in enough solvent to make 1 liter.
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