Question

20. The mass of one mole of lead (Pb) atoms is 207.2 g. Use a proportion to calculate the n

Answer 1

Answer:

a) atoms Pb = 4.3595 E22 amu

b) g = ( 6.022 E23 amu ) × ( Mw )

Explanation:

• m Pb = 207.2 g / mol Pb

sample:

∴ m = 15.00 g

a) atoms Pb = ?

• 1 mol ≡ 6.022 E23 amu

⇒ atoms Pb = (15.00g Pb)(mol Pb/207.2 g)(6.022 E23 amu/mol)

⇒ atoms Pb = 4.3595 E22 amu

b) relationship:

∴ 1 mol (n) ≡ 6.022 E23 amu......(1)

∴ mass (g) ≡ (Mw)×(n)

⇒ n = g / Mw..........(2)

∴ Mw: molecular weight

(1) = (2):

⇒ g / Mw ≡ 6.022 E23 amu

⇒ g ≡ ( 6.022 E23 amu ) × ( Mw )