Hamburger’s phenomenon is also known as

The exchange of Cl^- and HCO₃^- ions between the plasma and the RBC is called the chloride shift or Hamburger’s phenomenon. In systemic capillaries, CO₂ enters the RBCs and reacts with H₂O, in the presence of carbonic anhydrase, to form H₂CO₃^- which dissociates into  H⁺ and HCO₃^-. Some HCO₃^- diffuses out into the blood plasma, down its concentration gradient. The plasma membrane of the RBCs is nearly impermeable to cations. To maintain the electrical balance between blood plasma and RBCs, Cl^- move from the blood plasma into the RBC.