Question

3. We usually think of a metal when we are imagining a conductor; but an ionic solution is a conductor too. As an example, consider an ionic solution of calcium ions (Ca2+) with charge 2e and chlorine ions (Cl-) with charge -e. a. If 5.11 x 1018 chlorine ions go from a to b every 30.0 seconds, and 3.24 x 1018 calcium ions are going from b to a during the same interval, what current in mA is flowing through this solution? b. In what direction is the current flowing: from a to b, or from b to a?

Answer 1

Charge on each chlorine ion=-e=-1.6$\times$10^-19 C

Charge on each calcium ion=2e=3.2$\times$10^-19 C

No of chlorine ions go from a to b is=5.11$\times$10¹⁸

Total charge go from a to b= -1.6$\times$10^-19$\times$5.11$\times$10¹⁸=-0.8176 C

No of calcium ions go from b to a is=3.24$\times$10¹⁸

Total charge go from b to a= 3.2$\times$10^-19$\times$3.24$\times$10¹⁸= 1.0368 C

Total charge transferred  in interval of 30 sec is=1.0368+0.8176=1.8544 C

Current =1.8544/30=61.8 mA

Direction of current is always in direction of flow of +ve charge so direction of current is from b to a.