Begin Compartment 1 Compartment 2 K in Compartment 2 0.15M 0.15M Nat in Compartment 1 bUt only nat can move Nacl KCI Ion movement (b) Nat crosses into Na+一 Compartment 2 K but K stays in Compartment 2 Na Nat At the sodium K equilibrium potential buildup of positive charge in Compartment 2 produces an electrical potential that exactly offsets the Nat chemical concentration gradientBegin: K+ in Compartment 2, Na+ in Compartment 1; BUT only Na+ can move. Ion movement: Na+ crosses into Compartment 2; but K+ stays in Compartment 2. buildup of positive charge in Compartment 2 produces an electrical potential that exactly offsets the Na+ chemical concentration gradient. At the sodium equilibrium potential: