Calculate the number of atoms in each of the following. i. 52 moles of Argon (Ar) ii. 52 u of Helium (He)

Question

Calculate the number of atoms in each of the following.

i. 52 moles of Argon (Ar)

ii. 52 u of Helium (He)

iii. 52 g of Helium (He)

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Salim Ahmed Kawsar · Answer 1 · Feb 05, 2023 15:29:48

i. 52 moles of Argon

1 mole Argon atoms = 6.022 × 10²³ atoms of Ar

∴ Number of atoms = 52 mol × 6.022 × 10²³ atoms/mol

= 313.144 × 10²³ atoms of Argon

ii. 52 g of He

Molar mass of He = mass of 1 atom of He = 4.0 u

4.0 u = 1 He

∴ 52 u = x

∴ x = 52 u × \(\frac{1\,atom\,of\,He}{4.0u}\)

= 13 atoms of He

iii. 52 g of He

Molar mass of He = 4.0 g mol^-1

Number of moles = \(\frac{Mass\,of\,a\,substance}{Molar\,mass\,of\,a\,substance}\)

= \(\frac{52g}{4.0g\,mol^{-1}}\)

= 13 mol

Number of atoms of He = Number of moles × Avogadro’s constant

= 13 mol × 6.022 × 10²³ atoms/mol

= 78.286 × 10²³atoms of He

∴ i. Number of argon atoms in 52 moles = 313.144 × 10²³ atoms of Argon

ii. Number of helium atoms in 52 u = 13 atoms of He

iii. Number of helium atoms in 52 g = 78.286 × 10²³ atoms of He

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