Question

consider 100.0 ml of a buffer solution that contains [NaCH3COO]=[CH3COOH]=0.250 M

a) what is the pH of this buffer?

b) what should the ph of the buffer be after 50.0ml of water is added? explain

c) wtite balanced net ionic for the reaction that occurs whrn 1.0 M HCl ir added to this buffer.

d) after adding 10.0 ml of 1.0 M HCl what will the ph of the solution be?

e) as more 1.0 M HCl is slowly added at what ph will the buffer begin to fail?

Answer 1

cas Scho count Checconal, [, conto [es, conte]»[ uhkula 0,21m weak Acid (ethannic acid) Meu Coule = 1,8x1,5 Hodium ethanuales - (Cenjugate Bare) (Reported & Audec buffer values volume of suffer = forome (from City Couna) cal CA woh - Ch. cer-it Ho, ka = 1.8x105. Attro 0.25M 0.25M . At t= tog 0,25-n 0.25th a ~0.25 ~0.25 1.88165 a (Kalme, coole a [clycer](H) Cung coul] (HI) ano/8X/ut. pH = -log[144] . g (1,8X105) r pH = 4,24 ] (b) pH of the buffer will remain same even after adding some of water, as Kaz [ch cor ] [HT] [chor] Ka [ubun) o (Hr), so upen dolution Ka doesn't - Change as it in equilibrium constant - which depends only on Temperature)

Also on dilection concentration of both (C4100] 4 (CH, com] decreases, this, the reatio Kax[CH, Colift) . a in ccnstant value cogcon ] which is equal to [H] so pH will remain tame. HU (0) TH UN COUNG / luce will will altack on Chwn to form Cry Coun). Chona Not CH₂ LN + Hoteo HU Aty CNH (aq) + Nate (4) (ay) gr doesn't fully a'nize as it is a week acid. che contrar Ich contro e (d) chcoon 2 CH con 0.25M kaal,8x105. Ab t= t t He 0.04M 0.20m (Reaction proceeds some of IM HU û added but in backward direction) Buffer=250ml 0:29M 0.217 man [ht] = 1 / Ab because of ar 0.29.4 tutas 0.21+n times délution) .29 20-21 [et] x 0.21 0.29 = 21,8x10-5

[etla 9.48rxius pha-log, (H1] = -log(2-485 X10%) TPM = 4.609 re) as more amount of lm began to fall as the cas pH Hell is added their buffer wille the decreases by 1. from the Henderson - Hasselhatch equation pH = pka + log Cut, cal 1 Vial Ehwn), Wheen Hill is added, [CH₂ cew] will react with it to form [CH, CH] So, [ly cow] is decreasing to when this ratio [cy cout] reaches t/0.1 then pH becomes pka-l that's where buffer geli destroyed so, pH would be (4,79-1) a 3.74