question is in the description

Question

Carbonic acid, H2CO3, has two acidic hydrogens. A solution containing an unknown concentration of carbonic acid is titrated with potassium hydroxide. It requires 29.1 mL of 3.100 M KOH solution to titrate both acidic protons in 53.4 mL of the carbonic acid solution. Write a balanced net ionic equation for the neutralization reaction. Include physical states.

net ionic equation: H2CO3 (aq)+ 2OH- (aq)= 2H2O (l)+ CO3-2(aq)

Calculate the molarity of the carbonic acid solution.

concentration:

Answer 1

H₂CO₃(aq) + 2KOH(aq) ==> 2H₂O(l) + K₂CO₃(aq) ... molecular equation

H₂CO₃(aq) + 2K⁺(aq) + 2OH^-(aq) ==> 2H₂O(l) + 2K⁺(aq) + CO₃^2-(aq) ... ionic equation

H₂CO₃(aq) + 2OH^-(aq) ==> 2H₂O(l) + CO₃^2-(aq) ... net ionic equation

moles OH^- needed for titration = 29.1 ml x 1 L / 1000 ml x 3.100 mol / L = 0.09021 moles OH^-

moles H₂CO₃ present = 0.09021 mols OH^- x 1 mol H₂CO₃ / 2 mols OH^- = 0.0451 moles H₂CO₃

molarity of H₂CO₃ = 0.0451 moles / 53.4 ml x 1000 ml / L = 0.8447 moles / L = 0.845 M (3 sig.figs.)