Verified answer

Bonjour,

1) Volume total de solution :

V = V₁ + V₂ + V₃ + V₄ = 30,0.10⁻³ L

Quantités de matière et concentrations initiales :

. ni(HCOOH) = C₁V₁ = 3,0.10⁻² x 5,0.10⁻³ = 1,5.10⁻⁴ mol

⇒ [HCOOH] = ni(HCOOH)/V = 1,5.10⁻⁴/30,0.10⁻³ = 5,0.10⁻³ mol.L⁻¹

. ni(NH₃)= C₄V₄ = 9,0.10⁻² x 10,0.10⁻³ = 9,0.10⁻⁴ mol

⇒ [NH₃] = ni(NH₃)/V = 9,0.10⁻⁴/30,0.10⁻³ = 3,0.10⁻² mol.L⁻¹

. ni(HCOO⁻) = C₃V₃ = 6,0.10⁻² x 5,0.10⁻³ = 3,0.10⁻⁴ mol

⇒ [HCOO⁻] = ni(HCOO⁻)/V = 3,0.10⁻⁴/30,0.10⁻³ = 1,0.10⁻² mol.L⁻¹

. ni(NH₄⁺) = C₂V₂ = 4,5.10⁻² x 10,0.10⁻³ = 4,5.10⁻⁴ mol

⇒ [NH₄⁺] = ni(NH₄⁺)/V = 4,5.10⁻⁴/30,0.10⁻³ = 1,5.10⁻² mol.L⁻¹

2) Qr,i = [HCOO⁻] x [NH₄⁺] / [HCOOH] x [NH₃]

= (1,0.10⁻² x 1,5.10⁻²)/(5,0.10⁻³ x 3,0.10⁻²)

= 1

3) Qr,i << K

⇒ Le système évolue dans le sens direct