What is the product of the reaction at the tissue site when partial...

At the tissue site where partial pressure of CO₂ is high due to catabolism, CO₂ diffuses into blood (RBCs and plasma) and forms HCO3 and H⁺,. At the alveolar site where pCO2 is low, the reaction proceeds in the opposite direction leading to the formation of CO₂ and H₂O. Thus, CO₂ trapped as bicarbonate at the tissue level and transported to the alveoli is released out as CO₂ (Every 100 ml of deoxygenated blood delivers approximately 4 ml of CO₂ to the alveoli.