Question

Determine the volume you would need of each solution (acid/base and conjugate) to make a buffer with a specific pH. Please only use the acids, bases and salts from the table on page 87 in the lab manual. See below for assigned values, each person will be calculating volumes needed for an acidic buffer and a basic buffer. Chart from page 87 List 0.10 M CH,NH, 9.75 the 0.10 M NHỰC H. " List E 0.10 M HCOOH K - 1.8 X 104 10.10 M CHCOOH K - 1.8 x 10$ 0.10 M NH,OH K - 1.8 x 10 0.10 M CHÚNH, K = 4.4 x 10- 0.10 M CH,COONS 0.10 M HCOOK 0.10 M HCOONa 0.10 M CH,COOK Preparing a specific buffer. Recall from the introduc pk. - pH - log (A HAD) pK, - POH - log ([BH]/[B]) Target PH buffer values: Acidic PH= 4.40 Basic PH= 10.20

Answer 1

For an acidic buffer to function properly,it's pH range is pKa+1 to pKa -1.

So it's better to look for combination with pKa closer to required pH.

total volume of buffer was not mentioned so I have taken a standard value of one litres

Best Choice 10 Chool & CM₂ woNa pk = S-log108 - 4.744 Ph-pka + log [chlost] - 4. 4 = 4.244 +log [cycoon = 0.483 let total vol be llit = I let 7 V = I-V, Volior and 688.2 ml. =) Y = 1-0.473₂ 7 = t Vol of Cuz LOONa = 311,8 ml = 0.688264 Required pH = 10:20, 7 Pon = 38 Best Choice Ch NH₂ + Ch Nng CI Pleq = 4-logy.y = 3.36 pok-play + log Caud ) 3.8= 3.36 to log / 1.453 2 base I ad, vt = 1 lit - lovome - 3.750 = 1000 = = 3266.67ml Van = 266.67ml = 233. 33 ml Verway= 733.33 ml UuNn 2