Bonjour,
1)
M(C₆H₁₂O₆) = 6xM(C) + 12xM(H) + 6xM(O) = 6x12 + 12x1 + 6x16 = 180 g.mol⁻¹
M(NaCl) = M(Na) + M(Cl) = 23,0 + 35,5 = 58,5 g.mol⁻¹
M(C₂H₆O) = 2xM(C) + 6xM(H) + M(O) = 2x12 + 6x1 + 16 = 46 g.mol⁻¹
n(C₆H₁₂O₆) = m/M(C₆H₁₂O₆) = 250/180 ≈ 1,39 mol
n(NaCl) = m/M(NaCl) = 100.10⁻³/58,5 ≈ 1,71.10⁻³ mol
n(C₂H₆O) = m/M(C₂H₆O) = 0,50.10³/46 ≈ 10,9 mol
2) a) m = n x M(C₆H₁₂O₆) = 5,00.10⁻³ x 180 = 0,900 g
b) m = n x M(NaCl) = 2,50.10² x 58,5 = 1,46.10⁴ g soit 14,6 kg
c) m = n x M(C₂H₆O) = 1,20.10⁻² x 46 ≈ 0,55 g
