Question

: If a 250. mL sample of the above buffer solution initially has 0.0800 mol H2C6H5O7 - and 0.0600 mol HC6H5O7 2- , what would be the new concentration of HC6H5O7 2- after 25.0 mL of 0.125 M NaOH is added to the buffer?

Answer 1

Answer: New concentration of
`HC_(6)H_(5)O^(2-)_(7)` is 0.23 M.

Step-by-step explanation:

The given data is as follows.

Moles of
`HC_(6)H_(5)O^(2-)_(7)` = 0.06 mol

Moles of
`H_(2)C_(6)H_(5)O_(7)` = 0.08 mol

Therefore, moles of
`OH^(-)` added are as follows.

Moles of
`OH^(-)` =
`0.125 * (25)/(1000)`

= 0.003125 mol

Now, new moles of
`HC_(6)H_(5)O^(2-)_(7)` = 0.06 + 0.003125

= 0.063125

Therefore, new concentration of
`HC_(6)H_(5)O^(2-)_(7)` will be calculated as follows.

Concentration =
`(0.063125)/(0.275)`

= 0.23 M

Thus, we can conclude that new concentration of
`HC_(6)H_(5)O^(2-)_(7)` is 0.23 M.