Explain :Formula mass with an example.

1.	Explain :Formula mass with an example.
Answer» The formula mass of a substance is the sum of atomic masses of the atoms present in the formula. In substances such as sodium chloride, positive (sodium), and negative (chloride) entities are arranged in a three-dimensional structure in a way that one sodium (Na⁺) ion is surrounded by six chlorides (Cl^-) ions, all at the same distance from it and vice versa. Thus, sodium chloride does not contain discrete molecules as the constituent units. Therefore, NaCl is just the formula that is used to represent sodium chloride though it is not a molecule. In such compounds, the formula (i.e., NaCl) is used to calculate the formula mass instead of molecular mass. e.g. Formula mass of sodium chloride = atomic mass of sodium + atomic mass of chlorine = 23.0 u + 35.5 u = 58.5 u

Answer»

The formula mass of a substance is the sum of atomic masses of the atoms present in the formula.
In substances such as sodium chloride, positive (sodium), and negative (chloride) entities are arranged in a three-dimensional structure in a way that one sodium (Na⁺) ion is surrounded by six chlorides (Cl^-) ions, all at the same distance from it and vice versa. Thus, sodium chloride does not contain discrete molecules as the constituent units.
Therefore, NaCl is just the formula that is used to represent sodium chloride though it is not a molecule.
In such compounds, the formula (i.e., NaCl) is used to calculate the formula mass instead of molecular mass.

e.g.

Formula mass of sodium chloride = atomic mass of sodium + atomic mass of chlorine

= 23.0 u + 35.5 u = 58.5 u

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