What is the difference between molecular mass and formula unit mass?

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Molecular mass is for ionic compounds and formula mass is for molecules.

Molecular mass is for molecules and formula mass is for ionic compounds.

Both are exactly the same.

Molecular mass is for ionic compounds and formula mass is for Covalent compounds.

answer is C.

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Detailed Solution

The difference between molecular mass and formula unit mass is Molecular mass is for ionic compounds and formula mass is for Covalent compounds.

Let’s explore their differences in detail:

Molecular Mass:

Definition: The molecular mass is the sum of the atomic masses of all the atoms present in a molecule.
Applicable To: Used for covalent compounds, where atoms are bonded by sharing electrons.
Example Calculation:
- For water (H₂O):
  - Atomic mass of Hydrogen (H) = 1 u
  - Atomic mass of Oxygen (O) = 16 u
  - Molecular mass of H₂O = (2 × 1) + 16 = 18 u

Formula Unit Mass:

Definition: The formula unit mass is the sum of the atomic masses of all the ions in an ionic compound’s formula unit.
Applicable To: Used for ionic compounds, which consist of ions held together by electrostatic forces.
Example Calculation:
- For sodium chloride (NaCl):
  - Atomic mass of Sodium (Na) = 23 u
  - Atomic mass of Chlorine (Cl) = 35.5 u
  - Formula unit mass of NaCl = 23 + 35.5 = 58.5 u

Key differences between molecular mass and formula unit mass:

Aspect	Molecular Mass	Formula Unit Mass
Definition	Sum of atomic masses of all atoms in a molecule	Sum of atomic masses of ions in an ionic compound
Applicable To	Covalent compounds	Ionic compounds
Example	H₂O, CO₂	NaCl, KCl

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