What is the pH at the equivalence point of a weak...

What is the pH at the equivalence point of a weak base-strong acid titration if 20.00 mL of NaOCl requires 28.30 mL of 0.50 M HCl? Ka = 3.0 × 10?8 for HOCl. (pH = ?log[H3O+]; Kw = 1.0 × 10?14 at 25 °C; Kw = [H3O+] × [OH?]; Kw = Ka × Kb; pKa = ?log[Ka]; Buffer: pH = pKa + log([base]/[acid])) 0.30 3.18 4.03 3.76

Transcript

00:01 So here number of moles for scl should be equal to we can write number of mole of hocl, right? okay, so now it will be equal to molarity multiply with volume.

00:16 Therefore we can write value of molarity will be 0 .50 which are given in this question.

00:23 Malarity multiply with, at the place of volume we can write 28 .3 multiplied into the power minus 3, liter okay then equal to we can write one four point one five multiply with ten to the power minus three moles okay is that clear so now here we will write vt total volume so total volume should be we can write 20 .0 ml plus we can write 28 .30 okay ml then we will get here equal to 48 .3m.

01:08 3m.

01:10 Or we can write here in a liter we can write 48 .3 okay multiply with 10 to the power minus 3 liter okay now further we will move and here we can write molarity of h .o.

01:30 Cl should be equal to we can write number of moles over volume then now we can write 1 4 .15 multiplied 10 to the power minus 3 over we can write here 48 .3 multiply with 10 to the power minus 3 liter okay is that clear so this will be cancelled to each other then we will get here equal to 0 .29 okay is that clear so now we will move further okay and now here we can write reaction hocl gives product in h plus plus here we can write ocel minus is that clear so now here we can write add t equal to zero time then we can write it will be 0 .3 okay right and here t equal to equilibrium then we can write 0 .3 minus x so this will be x this will be x here test okay so now further we can write and here what we can write k a equal to and k equal to what we can write concentration h plus concentration here ocl minus concentration over we can write here h ocel concentration then we will write here x square over we can write 0 .29 minus x so here so here we can write at the place of k, we can write value 3 multiplied 10 to the power minus 8 equal to x squared over 0 .29 minus x.

03:19 Is that clear? so now we will solve then we will get here x equal to 9 .36 multiply with 10 to the power minus 5...

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