分子量计算器
以下详细说明暂以英文提供。
How the weight is built up
A formula encodes a recipe: each element symbol carries a subscript count, parentheses group atoms that share a multiplier, and a leading number on a hydrate part (the 5 in CuSO4·5H2O) repeats everything after the dot. The molecular weight is simply each element's standard atomic weight times its atom count, summed — water is 2 × 1.008 + 15.999 = 18.015 g/mol.
Reading the breakdown table
The table lists every element in the formula with its atom count and the mass it contributes, sorted from the heaviest contribution down. This is handy for spotting which element dominates a compound's mass — useful in percent-composition homework, stoichiometry, and when converting between mass and moles with our Molarity Calculator.
常见问题
What is the difference between molecular weight and molar mass?
They use the same number. Molecular weight is conventionally given in daltons for one molecule, while molar mass is the mass of one mole in grams — numerically identical because of how the mole is defined.
Can the calculator handle hydrates and parentheses?
Yes. Parenthesized groups multiply everything inside them, so Ca(OH)2 counts two OH units, and a hydrate dot repeats the trailing formula, so CuSO4·5H2O adds five full waters to the copper sulfate unit.
Why does an unknown symbol produce an error?
Only about thirty common elements are built in, covering most classroom and lab formulas. A symbol outside the table — or misplaced characters like a stray lowercase letter — is rejected rather than guessed at.