A buffer prepared by dissolving oxalic acid dihydrate (H2C2O4·2H2O) and disodium

Question

A buffer prepared by dissolving oxalic acid dihydrate (H2C2O4·2H2O) and disodium oxalate (Na2C2O4) in 1.00 L of water has a pH of 5.033. How many grams of oxalic acid dihydrate (MW = 126.07 g/mol) and disodium oxalate (MW = 133.99 g/mol) were required to prepare this buffer if the total oxalate concentration is 0.286 M? Oxalic acid has pKa values of 1.250 (pKa1) and 4.266 (pKa2).

A buffer prepared by dissolving oxalic acid dihydrate (H2C204 2H20) and disodium oxalate (NazC204) in 1.00 L of water has a pH of 5.033. How many grams of oxalic acid dihydrate (MW 126.07 g/mol) and disodium oxalate (MW 133.99 g/mol) were required to prepare this buffer if the total oxalate concentration is 0.286 M? Oxalic acid has pKa values of 1.250 (pKa) and 4.266 (pKa2). Number Mass of H20204 2H20 Number Mass of NazC204

Explanation / Answer

answer. given that pH =5.033, Volume=1L. pKa=(pKa1+pKa2)/2=(1.250+4.266)/2=2.76. (acid)+(salt)=0.286 M.-------(1) from Hinderson's equation pH=pKa+log(salt)/(acid),   log(salt)/(acid) =pH-pKa=5.033-2.76=2.27. log(salt)/(acid) =2.27 antilog 2.27=(salt)/(acid) (salt)/(acid)=186.2-----(2)

   (salt)=186.2(acid) ---------(3 ) from eq(1) and (3) (acid)=0.0015M,(salt)=0.2845M

mass of oxalic acid dihydrate=Mxmolar massx volume=0.0015x126.07x1=0.19 gms.

mass of oxalic acid dihydrate=Mxmolar massx volume=0.2845x133.99x1=38.12 gms.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.