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Question
Solve problem:
Calculate the number of atoms of the following. (Average atomic mass : N = 14 u, S = 32 u)
1.6 g of sulfur
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Solution
1.6 g of Sulphur (S)
Molar mass of sulphur = 32 g mol–1
Number of moles = `"Mass of a substance"/"Molar mass of a substance"=(1.6"g")/(32"g mol"^-1)` = 0.05 mol
Number of atoms of S = Number of moles × Avogadro's constant
= 0.05 mol × 6.022 × 1023 atoms/mol
= 0.3011 × 1023 atoms
= 3.011 × 1022 atoms of S
Number of sulphur atoms in 1.6 g = 3.011 × 1022 atoms of S
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