Question

Acid Ka
Acetic acid, CH3CO2H 1.7 x 10-5
Boric acid, H3BO3 5.8 x 10-10
Nitrous acid, HNO2 4.5 x 10-4
Hypochlorous acid, HOCl 3.5 x 10-8
Hydrocyanic acid, HCN 4.0 x 10-10
Hydrofluoric acid, HF 7.2 x 10-4
Potassium Hydrogen Phthalate (KHP) 4.0 x 10-6

1. A student following the procedure in this lab prepared 4solutions by adding 12.25, 23.00, 25.50, and 34.50 mL of a 8.25 x10-2 M NaOH solution to 50.00 mL of a 0.152 M solution of weakacid. The solutions were labeled 1, 2, 3, and 4 respectively. Eachof the solutions was diluted to a total volume of 250 mL with DIwater. The pH readings of these solutions were: (1) 6.64 (2) 6.98(3) 7.04 (4) 7.23

Initial number of moles 1,2,3,4

HAn(aq)

OH-(aq)


Number of moles at equilibrium 1,2,3,4

HAn(aq)

An-(aq)

Equilibrium concentrations, mol/L 1,2,3,4

HAn(aq)

An-(aq)

H3O+(aq)

Ka?
Average Ka?
Which of the weak acids do you think your unknown acid is?