Question

in a preliminary data, a solution containing 0.0837 M "X" and 0.0666 M internal standard give peak area Ax = 423 and As = 347. To analyze unknown, 10.0 mL of 0.146 internal standard were added to 10.0 mL of unknown. The mixture was diluted to 25.0 mL in volumetric flask. Final solution gave Ax = 553 and As = 582. What is [X]_i ?

Answer 1

In this. the data is obtained from an equipment a solution X is taken.

Hence to determine [X]_i we will go stepwise.

First, we will determine F,

A_x             A_s

_---- = F x ------

C_x             C_s

423                347

--------- = F x   -----------

0.0837           0.0666

F = 0.970

Now we have to determine [X]_i after 25mL dilution,

[X]_i = 0.146 x (10mL / 25mL)

A_x             A_s             553                     582

_---- = F x ------ ----> ------- = 0.970 x   ---------- = 0.065 M

C_x             C_s              C_x                          0.0666

[X]_i = 0.065 x (25mL / 10 mL)

[X]_i = 0.1625 M