Ion Concentration

Nernst Equation

Uses

Uses of Nernst Equation

• To predict effect of concentration ions on E value

• To calculate Kc

• To calculate K_sp

• To calculate pH

To predict effect of concentration of ions on emf

• For positive ions, the higher the concentration of ions, the more positive or the less negative the E value

• For negative ions, the higher the concentration of ions, the more negative of less positive the E value

• All the effect of concentrations of ions can be explain using Le Chatelier Principle

Multiple Choice

The E^o for copper half-cell is +0.34V. What is the possible E value for copper half-cell if the concentration of Cu²⁺ decrease from 1 mol dm^-3 to 0.5 mol dm^-3?

• +0.32

• +0.34

• +0.36

To calculate K_c

Multiple Choice

For the equilibrium in Daniell cell, Zn(s) + $$Cu^{2^+}$$  (aq) → $$Zn^{2^+}$$  (aq) + Cu (s), the expression for log  $$K_c$$    is

• $$\frac{2}{0.059}$$   $$E^ocell$$  

• $$\frac{1}{0.059}$$   $$E^ocell$$  

To find K_sp

Multiple Choice

Write the K_sp expression for lead(II) chloride

• K_sp = [Pb²⁺][Cl^-]

• K_sp = [Pb²⁺][Cl^-]²

• K_sp = [Pb²⁺]²[Cl^-]

To calculate pH

Multiple Choice

The higher the concentration the acid, the lower the pH and the higher the  $$E^o$$  of the cell

• True

• False