Question

A 1.00 L solution contains 22.52 g of nitrous acid, HNO2. What mass of sodium nitrite, NaNO2, should be added to it to make a buffer with a pH of 2.96? Ka (HNO2) = 4.0 × 10–4.

Answer 1

Ans! GVen that mdasty m2 A Mwt Vinn 2 2 52 47 Leev 0.479 M 0.4 8 M Gryen that kaCwo,) 40Alo imTo find au the mass Nano, to be adeleol to the Solutim to mate a baffer w pa.46 দৈ ptpha lag we knos that

lale have pH 2.46, pka-logka = 4-10g 4 -4-060 2 pka ANO,]z 0.48 M lao,l - 3. 398 ACid Ca t Na NozJ PPRato9THN 2.96-3.348 + logNa No,1- loal HNo og Na No J2.96-3.398logHNo 2.96-3.398 log lo.481 CHNG04M

loglNaNo 2.46-3.398 o. 319 sd.757 CNANOJ= 0.175 M. wt wt wtz 0.175 x 69 12.07 9 12.67 Sodium nrtte added tothe sdutn a bfter aith a 2.5 4 NO, m IL t make pt 2.16