Question 1

What is the difference between molar mass and molecular weight?

Accepted Answer

Numerically they are the same. Molecular weight (relative molecular mass) is dimensionless; molar mass carries the unit g/mol.

Question 2

Is molar mass the same as monoisotopic mass?

Accepted Answer

No. Monoisotopic mass uses only the most abundant isotope of each element and is used in mass spectrometry; molar mass uses the natural average.

Question 3

How do I enter a hydrate like copper sulfate pentahydrate?

Accepted Answer

Type CuSO4·5H2O or CuSO4*5H2O. The result should be about 249.7 g/mol.

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