Answer:
Ratio of [CO₃²⁻] / [H₂CO₃] is 1.0x10⁻⁸
Explanation:
Based on the equilibriums:
H₂CO₃ ⇄ H⁺ + HCO₃⁻ Ka1 = 4.3x10⁻⁷
HCO₃⁻ ⇄ H⁺ + CO₃²⁻ Ka2 = 4.8x10⁻¹¹
The sum of both equilibriums is:
H₂CO₃ ⇄ 2 H⁺ + CO₃²⁻ K' = 4.3x10⁻⁷*4.8x10⁻¹¹ = 2.064x10⁻¹⁷
Where K' is defined as:
K' = 2.064x10⁻¹⁷ = [H⁺]² [CO₃²⁻] / [H₂CO₃]
If concentration of H⁺ is 4.5x10⁻⁵M:
K' = 2.064x10⁻¹⁷ = [4.5x10⁻⁵]² [CO₃²⁻] / [H₂CO₃]
1.0x10⁻⁸ = [CO₃²⁻] / [H₂CO₃]
Thus, <em>ratio of [CO₃²⁻] / [H₂CO₃] is 1.0x10⁻⁸</em>
