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Question
Solve problem:
Calculate the number of an atom of the following (Given: Atomic mass of I = 127 u).
254 g of iodine (I)
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Solution
254 g of iodine (I)
Atomic mass of iodine = 127 u
∴ Molar mass of iodine = 127 g mol–1
Now,
Number of moles = `"Mass of a substance"/"Molar mass of a substance"`
= `(254 "g")/(127 "g" "mol"^-1)`
= 2 mol
Now,
Number of atoms = Number of moles × Avogadro's constant
= 2 mol × 6.022 × 1023 atoms/mol
= 12.044 × 1023 atoms
= 1.2044 × 1024 atoms
Number of iodine atoms in 254 g= 1.2044 × 1024 atoms
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