Question

A solution containing Cd21 was analyzed voltammetrically using the standard addition method. Twenty-

five milliliters of the deaerated solution, which was 1 M in HNO3, produced a net limiting current of 1.41 μA

at a rotating mercury film working electrode at a potential of 20.85 V (versus SCE). Following addition of

5.00 mL of a 2.50 3 1023M standard Cd21 solution, the resulting solution produced a current of 4.93 μA.

Calculate the concentration of Cd21 in the sample.

Short answer

cu = 2.23 × 10^-4 M

Step-by-step solution

Explanation

i_{1 =}kc_u

_where,

i_{1 =}1.78μA

c_{u =} is the concentration of the unknown

i_{2 =}k(25c_{u +}5c_u*2.25 * 10^-3/25+5)

= 4.48μA

Given information

cu = 2.23 × 10^-4 M