Question

What is the pH of a 0.10M solution of HC2H3)2 that dissociates 5.8%? (ans: 2.24)

Answer 1

The pH is 2.24.

Explanation:

Note: 5.8 % ionization corresponds to a decrease in concentration of

`"0.058 × 0.10 mol/L = 0.0058 mol/L"`

We can use an ICE table to help with the calculation.

`color(white)(mmmmmmml)"HA" + "H"_2"O" ⇌ color(white)(mll)"A"^"-" + color(white)(mll)"H"_3"O"^"+"`
`"I/mol·L"^"-1":color(white)(mll)0.10color(white)(mmmmmmmll)0color(white)(mmmml)0`
`"C/mol·L"^"-1":color(white)(m)"-0.0058"color(white)(mmmml)"+0.0058"color(white)(ml)"+0.0058"`
`"E/mol·L"^"-1":color(white)(ml)0.0942color(white)(mmmmml)0.0058color(white)(mm)0.0058`

`["H"_3"O"^"+"] = "0.0058 mol/L"`

`"pH" = "-log"["H"_3"O"^"+"] = "-log0.0058 = 2.24"`