it Buffer solution Answer the toflowing questions based on Act ICHoom , show you
ID: 103429 • Letter: I
Question
it Buffer solution Answer the toflowing questions based on Act ICHoom , show you cekculation clearly) cooH) has pke of 4.75. (Kw- 10 1 Cekoulate the Ne ot 2. What t is the pH range of buffers can be made of acetic acid and acetate and A) 3. For a buffer solution of pH-4.25 made of acetic acld and acetate (HA a calculate [H'1 in the buffer b. Calculate [OH] in the buffer (IH' IOH1-104) c. Calculate [A]/[HA] in the buffer d. Calculate (HAl and [A] if the above buffer's concentration is 0.20 M in total (HA] A 0.2). Calculate how much acetic acid in grams is needed to make 2.00 L buffer mention above (the molar mass of acetic acid is 60.0 g/mol) e.Explanation / Answer
Q1.
if pKa = 4.75
then
Ka = 10^-pKa = 10^4.75 = 1.8*10^-5
Q2
ph range for this buffer, is +/-1 uinits of the pKa data so
pH min = 3.75, pH max = 5.75
Q3
a)
i
[H+] from:
pH = 4.25
[H+] = 10^-pH = 10^-4.25 = 0.000056 M
ii
[OH-] = (10^-14)/(0.000056) = 1.785*10^-10
iii
pH = pKa + log(A-/HA)
4.25 = 4.75 + log(A/HA)
A/HA = 10^(4.25 - 4.75) =
A-/HA =0.3162
d.
A- +HA = 0.2
A- = 0.3162*HA then
0.3162*HA + HA = 0.2
HA = 0.2/(0.3162+1) = 0.15195 M
A- = 0.3162*0.2 = 0.06324M
e.
mol of acid = MV = 0.15195 *2 = 0.3039 mol
mass = mol*MW = 0.3039*60 = 18.23 g of acid
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