Question

Which of the following is a proper buffer substituent pair?

a.
oxalic acid and lithium oxalate
c.
Neither a nor b
b.
carbonic acid and sodium carbonate
d.
Both a and b
​

Answer 1

`\boxed{\text{c. Neither a nor b is correct}}`

Step-by-step explanation:

A buffer pair consists of either

• A weak acid and its salt or
• A weak base and its salt

(a) Oxalic acid and sodium oxalate

`\rm H$_2$C$_2$O$_4$ + Li$_2$C$_2$O$_4$ \longrightarrow \, $2LiHC$_2$O$_4$`

Oxalic acid is an acid and lithium acid is a base. Together, they will neutralise each other and form the salt LiHC₂O₄.

A solution of LiHC₂O₄ is not a buffer.

The correct buffer pair is H₂C₂O₄ and LiHC₂O₄

(b) Carbonic acid and sodium carbonate

`\rm H$_2$CO$_3$ + Na$_2$CO$_3$ $\longrightarrow \,$ 2NaHCO$_3$`

The carbonic acid and the sodium carbonate will neutralise each other and form the salt NaHCO₃.

A solution of NaHCO₃ is not a buffer.

The correct buffer pair is H₂CO₃ and NaHCO₃

`\boxed{\textbf{Neither a nor b is correct}}`